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PKGBUILDs/core/linux-kirkwood-dt/bfq-v8r3-for-4.8.patch
moonman d55facaaf0 core/linux-kirkwood-dt to 4.8.1-1
2016-10-10 01:00:26 -06:00

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diff -ruN linux-4.8/block/bfq-cgroup.c linux-bfq-bfq-v8/block/bfq-cgroup.c
--- linux-4.8/block/bfq-cgroup.c 1970-01-01 00:00:00.000000000 +0000
+++ linux-bfq-bfq-v8/block/bfq-cgroup.c 2016-10-06 07:08:26.000000000 +0000
@@ -0,0 +1,1192 @@
+/*
+ * BFQ: CGROUPS support.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org>
+ *
+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
+ * file.
+ */
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+
+/* bfqg stats flags */
+enum bfqg_stats_flags {
+ BFQG_stats_waiting = 0,
+ BFQG_stats_idling,
+ BFQG_stats_empty,
+};
+
+#define BFQG_FLAG_FNS(name) \
+static void bfqg_stats_mark_##name(struct bfqg_stats *stats) \
+{ \
+ stats->flags |= (1 << BFQG_stats_##name); \
+} \
+static void bfqg_stats_clear_##name(struct bfqg_stats *stats) \
+{ \
+ stats->flags &= ~(1 << BFQG_stats_##name); \
+} \
+static int bfqg_stats_##name(struct bfqg_stats *stats) \
+{ \
+ return (stats->flags & (1 << BFQG_stats_##name)) != 0; \
+} \
+
+BFQG_FLAG_FNS(waiting)
+BFQG_FLAG_FNS(idling)
+BFQG_FLAG_FNS(empty)
+#undef BFQG_FLAG_FNS
+
+/* This should be called with the queue_lock held. */
+static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
+{
+ unsigned long long now;
+
+ if (!bfqg_stats_waiting(stats))
+ return;
+
+ now = sched_clock();
+ if (time_after64(now, stats->start_group_wait_time))
+ blkg_stat_add(&stats->group_wait_time,
+ now - stats->start_group_wait_time);
+ bfqg_stats_clear_waiting(stats);
+}
+
+/* This should be called with the queue_lock held. */
+static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
+ struct bfq_group *curr_bfqg)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+
+ if (bfqg_stats_waiting(stats))
+ return;
+ if (bfqg == curr_bfqg)
+ return;
+ stats->start_group_wait_time = sched_clock();
+ bfqg_stats_mark_waiting(stats);
+}
+
+/* This should be called with the queue_lock held. */
+static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
+{
+ unsigned long long now;
+
+ if (!bfqg_stats_empty(stats))
+ return;
+
+ now = sched_clock();
+ if (time_after64(now, stats->start_empty_time))
+ blkg_stat_add(&stats->empty_time,
+ now - stats->start_empty_time);
+ bfqg_stats_clear_empty(stats);
+}
+
+static void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
+{
+ blkg_stat_add(&bfqg->stats.dequeue, 1);
+}
+
+static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+
+ if (blkg_rwstat_total(&stats->queued))
+ return;
+
+ /*
+ * group is already marked empty. This can happen if bfqq got new
+ * request in parent group and moved to this group while being added
+ * to service tree. Just ignore the event and move on.
+ */
+ if (bfqg_stats_empty(stats))
+ return;
+
+ stats->start_empty_time = sched_clock();
+ bfqg_stats_mark_empty(stats);
+}
+
+static void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+
+ if (bfqg_stats_idling(stats)) {
+ unsigned long long now = sched_clock();
+
+ if (time_after64(now, stats->start_idle_time))
+ blkg_stat_add(&stats->idle_time,
+ now - stats->start_idle_time);
+ bfqg_stats_clear_idling(stats);
+ }
+}
+
+static void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+
+ stats->start_idle_time = sched_clock();
+ bfqg_stats_mark_idling(stats);
+}
+
+static void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+
+ blkg_stat_add(&stats->avg_queue_size_sum,
+ blkg_rwstat_total(&stats->queued));
+ blkg_stat_add(&stats->avg_queue_size_samples, 1);
+ bfqg_stats_update_group_wait_time(stats);
+}
+
+static struct blkcg_policy blkcg_policy_bfq;
+
+/*
+ * blk-cgroup policy-related handlers
+ * The following functions help in converting between blk-cgroup
+ * internal structures and BFQ-specific structures.
+ */
+
+static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd)
+{
+ return pd ? container_of(pd, struct bfq_group, pd) : NULL;
+}
+
+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg)
+{
+ return pd_to_blkg(&bfqg->pd);
+}
+
+static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg)
+{
+ struct blkg_policy_data *pd = blkg_to_pd(blkg, &blkcg_policy_bfq);
+
+ return pd_to_bfqg(pd);
+}
+
+/*
+ * bfq_group handlers
+ * The following functions help in navigating the bfq_group hierarchy
+ * by allowing to find the parent of a bfq_group or the bfq_group
+ * associated to a bfq_queue.
+ */
+
+static struct bfq_group *bfqg_parent(struct bfq_group *bfqg)
+{
+ struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent;
+
+ return pblkg ? blkg_to_bfqg(pblkg) : NULL;
+}
+
+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
+{
+ struct bfq_entity *group_entity = bfqq->entity.parent;
+
+ return group_entity ? container_of(group_entity, struct bfq_group,
+ entity) :
+ bfqq->bfqd->root_group;
+}
+
+/*
+ * The following two functions handle get and put of a bfq_group by
+ * wrapping the related blk-cgroup hooks.
+ */
+
+static void bfqg_get(struct bfq_group *bfqg)
+{
+ return blkg_get(bfqg_to_blkg(bfqg));
+}
+
+static void bfqg_put(struct bfq_group *bfqg)
+{
+ return blkg_put(bfqg_to_blkg(bfqg));
+}
+
+static void bfqg_stats_update_io_add(struct bfq_group *bfqg,
+ struct bfq_queue *bfqq,
+ int op, int op_flags)
+{
+ blkg_rwstat_add(&bfqg->stats.queued, op, op_flags, 1);
+ bfqg_stats_end_empty_time(&bfqg->stats);
+ if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
+ bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
+}
+
+static void bfqg_stats_update_io_remove(struct bfq_group *bfqg, int op,
+ int op_flags)
+{
+ blkg_rwstat_add(&bfqg->stats.queued, op, op_flags, -1);
+}
+
+static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, int op,
+ int op_flags)
+{
+ blkg_rwstat_add(&bfqg->stats.merged, op, op_flags, 1);
+}
+
+static void bfqg_stats_update_completion(struct bfq_group *bfqg,
+ uint64_t start_time, uint64_t io_start_time, int op,
+ int op_flags)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+ unsigned long long now = sched_clock();
+
+ if (time_after64(now, io_start_time))
+ blkg_rwstat_add(&stats->service_time, op, op_flags,
+ now - io_start_time);
+ if (time_after64(io_start_time, start_time))
+ blkg_rwstat_add(&stats->wait_time, op, op_flags,
+ io_start_time - start_time);
+}
+
+/* @stats = 0 */
+static void bfqg_stats_reset(struct bfqg_stats *stats)
+{
+ /* queued stats shouldn't be cleared */
+ blkg_rwstat_reset(&stats->merged);
+ blkg_rwstat_reset(&stats->service_time);
+ blkg_rwstat_reset(&stats->wait_time);
+ blkg_stat_reset(&stats->time);
+ blkg_stat_reset(&stats->avg_queue_size_sum);
+ blkg_stat_reset(&stats->avg_queue_size_samples);
+ blkg_stat_reset(&stats->dequeue);
+ blkg_stat_reset(&stats->group_wait_time);
+ blkg_stat_reset(&stats->idle_time);
+ blkg_stat_reset(&stats->empty_time);
+}
+
+/* @to += @from */
+static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
+{
+ if (!to || !from)
+ return;
+
+ /* queued stats shouldn't be cleared */
+ blkg_rwstat_add_aux(&to->merged, &from->merged);
+ blkg_rwstat_add_aux(&to->service_time, &from->service_time);
+ blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
+ blkg_stat_add_aux(&from->time, &from->time);
+ blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
+ blkg_stat_add_aux(&to->avg_queue_size_samples,
+ &from->avg_queue_size_samples);
+ blkg_stat_add_aux(&to->dequeue, &from->dequeue);
+ blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
+ blkg_stat_add_aux(&to->idle_time, &from->idle_time);
+ blkg_stat_add_aux(&to->empty_time, &from->empty_time);
+}
+
+/*
+ * Transfer @bfqg's stats to its parent's dead_stats so that the ancestors'
+ * recursive stats can still account for the amount used by this bfqg after
+ * it's gone.
+ */
+static void bfqg_stats_xfer_dead(struct bfq_group *bfqg)
+{
+ struct bfq_group *parent;
+
+ if (!bfqg) /* root_group */
+ return;
+
+ parent = bfqg_parent(bfqg);
+
+ lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock);
+
+ if (unlikely(!parent))
+ return;
+
+ bfqg_stats_add_aux(&parent->stats, &bfqg->stats);
+ bfqg_stats_reset(&bfqg->stats);
+}
+
+static void bfq_init_entity(struct bfq_entity *entity,
+ struct bfq_group *bfqg)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ entity->weight = entity->new_weight;
+ entity->orig_weight = entity->new_weight;
+ if (bfqq) {
+ bfqq->ioprio = bfqq->new_ioprio;
+ bfqq->ioprio_class = bfqq->new_ioprio_class;
+ bfqg_get(bfqg);
+ }
+ entity->parent = bfqg->my_entity;
+ entity->sched_data = &bfqg->sched_data;
+}
+
+static void bfqg_stats_exit(struct bfqg_stats *stats)
+{
+ blkg_rwstat_exit(&stats->merged);
+ blkg_rwstat_exit(&stats->service_time);
+ blkg_rwstat_exit(&stats->wait_time);
+ blkg_rwstat_exit(&stats->queued);
+ blkg_stat_exit(&stats->time);
+ blkg_stat_exit(&stats->avg_queue_size_sum);
+ blkg_stat_exit(&stats->avg_queue_size_samples);
+ blkg_stat_exit(&stats->dequeue);
+ blkg_stat_exit(&stats->group_wait_time);
+ blkg_stat_exit(&stats->idle_time);
+ blkg_stat_exit(&stats->empty_time);
+}
+
+static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
+{
+ if (blkg_rwstat_init(&stats->merged, gfp) ||
+ blkg_rwstat_init(&stats->service_time, gfp) ||
+ blkg_rwstat_init(&stats->wait_time, gfp) ||
+ blkg_rwstat_init(&stats->queued, gfp) ||
+ blkg_stat_init(&stats->time, gfp) ||
+ blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
+ blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
+ blkg_stat_init(&stats->dequeue, gfp) ||
+ blkg_stat_init(&stats->group_wait_time, gfp) ||
+ blkg_stat_init(&stats->idle_time, gfp) ||
+ blkg_stat_init(&stats->empty_time, gfp)) {
+ bfqg_stats_exit(stats);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)
+{
+ return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL;
+}
+
+static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg)
+{
+ return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq));
+}
+
+static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
+{
+ struct bfq_group_data *bgd;
+
+ bgd = kzalloc(sizeof(*bgd), GFP_KERNEL);
+ if (!bgd)
+ return NULL;
+ return &bgd->pd;
+}
+
+static void bfq_cpd_init(struct blkcg_policy_data *cpd)
+{
+ struct bfq_group_data *d = cpd_to_bfqgd(cpd);
+
+ d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
+ CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL;
+}
+
+static void bfq_cpd_free(struct blkcg_policy_data *cpd)
+{
+ kfree(cpd_to_bfqgd(cpd));
+}
+
+static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
+{
+ struct bfq_group *bfqg;
+
+ bfqg = kzalloc_node(sizeof(*bfqg), gfp, node);
+ if (!bfqg)
+ return NULL;
+
+ if (bfqg_stats_init(&bfqg->stats, gfp)) {
+ kfree(bfqg);
+ return NULL;
+ }
+
+ return &bfqg->pd;
+}
+
+static void bfq_pd_init(struct blkg_policy_data *pd)
+{
+ struct blkcg_gq *blkg;
+ struct bfq_group *bfqg;
+ struct bfq_data *bfqd;
+ struct bfq_entity *entity;
+ struct bfq_group_data *d;
+
+ blkg = pd_to_blkg(pd);
+ BUG_ON(!blkg);
+ bfqg = blkg_to_bfqg(blkg);
+ bfqd = blkg->q->elevator->elevator_data;
+ entity = &bfqg->entity;
+ d = blkcg_to_bfqgd(blkg->blkcg);
+
+ entity->orig_weight = entity->weight = entity->new_weight = d->weight;
+ entity->my_sched_data = &bfqg->sched_data;
+ bfqg->my_entity = entity; /*
+ * the root_group's will be set to NULL
+ * in bfq_init_queue()
+ */
+ bfqg->bfqd = bfqd;
+ bfqg->active_entities = 0;
+ bfqg->rq_pos_tree = RB_ROOT;
+}
+
+static void bfq_pd_free(struct blkg_policy_data *pd)
+{
+ struct bfq_group *bfqg = pd_to_bfqg(pd);
+
+ bfqg_stats_exit(&bfqg->stats);
+ return kfree(bfqg);
+}
+
+static void bfq_pd_reset_stats(struct blkg_policy_data *pd)
+{
+ struct bfq_group *bfqg = pd_to_bfqg(pd);
+
+ bfqg_stats_reset(&bfqg->stats);
+}
+
+static void bfq_group_set_parent(struct bfq_group *bfqg,
+ struct bfq_group *parent)
+{
+ struct bfq_entity *entity;
+
+ BUG_ON(!parent);
+ BUG_ON(!bfqg);
+ BUG_ON(bfqg == parent);
+
+ entity = &bfqg->entity;
+ entity->parent = parent->my_entity;
+ entity->sched_data = &parent->sched_data;
+}
+
+static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd,
+ struct blkcg *blkcg)
+{
+ struct blkcg_gq *blkg;
+
+ blkg = blkg_lookup(blkcg, bfqd->queue);
+ if (likely(blkg))
+ return blkg_to_bfqg(blkg);
+ return NULL;
+}
+
+static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
+ struct blkcg *blkcg)
+{
+ struct bfq_group *bfqg, *parent;
+ struct bfq_entity *entity;
+
+ assert_spin_locked(bfqd->queue->queue_lock);
+
+ bfqg = bfq_lookup_bfqg(bfqd, blkcg);
+
+ if (unlikely(!bfqg))
+ return NULL;
+
+ /*
+ * Update chain of bfq_groups as we might be handling a leaf group
+ * which, along with some of its relatives, has not been hooked yet
+ * to the private hierarchy of BFQ.
+ */
+ entity = &bfqg->entity;
+ for_each_entity(entity) {
+ bfqg = container_of(entity, struct bfq_group, entity);
+ BUG_ON(!bfqg);
+ if (bfqg != bfqd->root_group) {
+ parent = bfqg_parent(bfqg);
+ if (!parent)
+ parent = bfqd->root_group;
+ BUG_ON(!parent);
+ bfq_group_set_parent(bfqg, parent);
+ }
+ }
+
+ return bfqg;
+}
+
+static void bfq_pos_tree_add_move(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq);
+
+static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ bool compensate,
+ enum bfqq_expiration reason);
+
+/**
+ * bfq_bfqq_move - migrate @bfqq to @bfqg.
+ * @bfqd: queue descriptor.
+ * @bfqq: the queue to move.
+ * @bfqg: the group to move to.
+ *
+ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
+ * it on the new one. Avoid putting the entity on the old group idle tree.
+ *
+ * Must be called under the queue lock; the cgroup owning @bfqg must
+ * not disappear (by now this just means that we are called under
+ * rcu_read_lock()).
+ */
+static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct bfq_group *bfqg)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ BUG_ON(!bfq_bfqq_busy(bfqq) && !RB_EMPTY_ROOT(&bfqq->sort_list));
+ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list) && !entity->on_st);
+ BUG_ON(bfq_bfqq_busy(bfqq) && RB_EMPTY_ROOT(&bfqq->sort_list)
+ && entity->on_st &&
+ bfqq != bfqd->in_service_queue);
+ BUG_ON(!bfq_bfqq_busy(bfqq) && bfqq == bfqd->in_service_queue);
+
+ /* If bfqq is empty, then bfq_bfqq_expire also invokes
+ * bfq_del_bfqq_busy, thereby removing bfqq and its entity
+ * from data structures related to current group. Otherwise we
+ * need to remove bfqq explicitly with bfq_deactivate_bfqq, as
+ * we do below.
+ */
+ if (bfqq == bfqd->in_service_queue)
+ bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
+ false, BFQ_BFQQ_PREEMPTED);
+
+ BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq)
+ && &bfq_entity_service_tree(entity)->idle !=
+ entity->tree);
+
+ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq));
+
+ if (bfq_bfqq_busy(bfqq))
+ bfq_deactivate_bfqq(bfqd, bfqq, 0);
+ else if (entity->on_st) {
+ BUG_ON(&bfq_entity_service_tree(entity)->idle !=
+ entity->tree);
+ bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
+ }
+ bfqg_put(bfqq_group(bfqq));
+
+ /*
+ * Here we use a reference to bfqg. We don't need a refcounter
+ * as the cgroup reference will not be dropped, so that its
+ * destroy() callback will not be invoked.
+ */
+ entity->parent = bfqg->my_entity;
+ entity->sched_data = &bfqg->sched_data;
+ bfqg_get(bfqg);
+
+ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq));
+ if (bfq_bfqq_busy(bfqq)) {
+ bfq_pos_tree_add_move(bfqd, bfqq);
+ bfq_activate_bfqq(bfqd, bfqq);
+ }
+
+ if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
+ bfq_schedule_dispatch(bfqd);
+ BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq)
+ && &bfq_entity_service_tree(entity)->idle !=
+ entity->tree);
+}
+
+/**
+ * __bfq_bic_change_cgroup - move @bic to @cgroup.
+ * @bfqd: the queue descriptor.
+ * @bic: the bic to move.
+ * @blkcg: the blk-cgroup to move to.
+ *
+ * Move bic to blkcg, assuming that bfqd->queue is locked; the caller
+ * has to make sure that the reference to cgroup is valid across the call.
+ *
+ * NOTE: an alternative approach might have been to store the current
+ * cgroup in bfqq and getting a reference to it, reducing the lookup
+ * time here, at the price of slightly more complex code.
+ */
+static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
+ struct bfq_io_cq *bic,
+ struct blkcg *blkcg)
+{
+ struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0);
+ struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1);
+ struct bfq_group *bfqg;
+ struct bfq_entity *entity;
+
+ lockdep_assert_held(bfqd->queue->queue_lock);
+
+ bfqg = bfq_find_set_group(bfqd, blkcg);
+ if (async_bfqq) {
+ entity = &async_bfqq->entity;
+
+ if (entity->sched_data != &bfqg->sched_data) {
+ bic_set_bfqq(bic, NULL, 0);
+ bfq_log_bfqq(bfqd, async_bfqq,
+ "bic_change_group: %p %d",
+ async_bfqq,
+ async_bfqq->ref);
+ bfq_put_queue(async_bfqq);
+ }
+ }
+
+ if (sync_bfqq) {
+ entity = &sync_bfqq->entity;
+ if (entity->sched_data != &bfqg->sched_data)
+ bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
+ }
+
+ return bfqg;
+}
+
+static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
+{
+ struct bfq_data *bfqd = bic_to_bfqd(bic);
+ struct bfq_group *bfqg = NULL;
+ uint64_t serial_nr;
+
+ rcu_read_lock();
+ serial_nr = bio_blkcg(bio)->css.serial_nr;
+
+ /*
+ * Check whether blkcg has changed. The condition may trigger
+ * spuriously on a newly created cic but there's no harm.
+ */
+ if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr))
+ goto out;
+
+ bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio));
+ bic->blkcg_serial_nr = serial_nr;
+out:
+ rcu_read_unlock();
+}
+
+/**
+ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
+ * @st: the service tree being flushed.
+ */
+static void bfq_flush_idle_tree(struct bfq_service_tree *st)
+{
+ struct bfq_entity *entity = st->first_idle;
+
+ for (; entity ; entity = st->first_idle)
+ __bfq_deactivate_entity(entity, 0);
+}
+
+/**
+ * bfq_reparent_leaf_entity - move leaf entity to the root_group.
+ * @bfqd: the device data structure with the root group.
+ * @entity: the entity to move.
+ */
+static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ BUG_ON(!bfqq);
+ bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
+}
+
+/**
+ * bfq_reparent_active_entities - move to the root group all active
+ * entities.
+ * @bfqd: the device data structure with the root group.
+ * @bfqg: the group to move from.
+ * @st: the service tree with the entities.
+ *
+ * Needs queue_lock to be taken and reference to be valid over the call.
+ */
+static void bfq_reparent_active_entities(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ struct bfq_service_tree *st)
+{
+ struct rb_root *active = &st->active;
+ struct bfq_entity *entity = NULL;
+
+ if (!RB_EMPTY_ROOT(&st->active))
+ entity = bfq_entity_of(rb_first(active));
+
+ for (; entity ; entity = bfq_entity_of(rb_first(active)))
+ bfq_reparent_leaf_entity(bfqd, entity);
+
+ if (bfqg->sched_data.in_service_entity)
+ bfq_reparent_leaf_entity(bfqd,
+ bfqg->sched_data.in_service_entity);
+}
+
+/**
+ * bfq_pd_offline - deactivate the entity associated with @pd,
+ * and reparent its children entities.
+ * @pd: descriptor of the policy going offline.
+ *
+ * blkio already grabs the queue_lock for us, so no need to use
+ * RCU-based magic
+ */
+static void bfq_pd_offline(struct blkg_policy_data *pd)
+{
+ struct bfq_service_tree *st;
+ struct bfq_group *bfqg;
+ struct bfq_data *bfqd;
+ struct bfq_entity *entity;
+ int i;
+
+ BUG_ON(!pd);
+ bfqg = pd_to_bfqg(pd);
+ BUG_ON(!bfqg);
+ bfqd = bfqg->bfqd;
+ BUG_ON(bfqd && !bfqd->root_group);
+
+ entity = bfqg->my_entity;
+
+ if (!entity) /* root group */
+ return;
+
+ /*
+ * Empty all service_trees belonging to this group before
+ * deactivating the group itself.
+ */
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
+ BUG_ON(!bfqg->sched_data.service_tree);
+ st = bfqg->sched_data.service_tree + i;
+ /*
+ * The idle tree may still contain bfq_queues belonging
+ * to exited task because they never migrated to a different
+ * cgroup from the one being destroyed now. No one else
+ * can access them so it's safe to act without any lock.
+ */
+ bfq_flush_idle_tree(st);
+
+ /*
+ * It may happen that some queues are still active
+ * (busy) upon group destruction (if the corresponding
+ * processes have been forced to terminate). We move
+ * all the leaf entities corresponding to these queues
+ * to the root_group.
+ * Also, it may happen that the group has an entity
+ * in service, which is disconnected from the active
+ * tree: it must be moved, too.
+ * There is no need to put the sync queues, as the
+ * scheduler has taken no reference.
+ */
+ bfq_reparent_active_entities(bfqd, bfqg, st);
+ BUG_ON(!RB_EMPTY_ROOT(&st->active));
+ BUG_ON(!RB_EMPTY_ROOT(&st->idle));
+ }
+ BUG_ON(bfqg->sched_data.next_in_service);
+ BUG_ON(bfqg->sched_data.in_service_entity);
+
+ __bfq_deactivate_entity(entity, 0);
+ bfq_put_async_queues(bfqd, bfqg);
+ BUG_ON(entity->tree);
+
+ /*
+ * @blkg is going offline and will be ignored by
+ * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
+ * that they don't get lost. If IOs complete after this point, the
+ * stats for them will be lost. Oh well...
+ */
+ bfqg_stats_xfer_dead(bfqg);
+}
+
+static void bfq_end_wr_async(struct bfq_data *bfqd)
+{
+ struct blkcg_gq *blkg;
+
+ list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) {
+ struct bfq_group *bfqg = blkg_to_bfqg(blkg);
+ BUG_ON(!bfqg);
+
+ bfq_end_wr_async_queues(bfqd, bfqg);
+ }
+ bfq_end_wr_async_queues(bfqd, bfqd->root_group);
+}
+
+static int bfq_io_show_weight(struct seq_file *sf, void *v)
+{
+ struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
+ struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
+ unsigned int val = 0;
+
+ if (bfqgd)
+ val = bfqgd->weight;
+
+ seq_printf(sf, "%u\n", val);
+
+ return 0;
+}
+
+static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
+ struct cftype *cftype,
+ u64 val)
+{
+ struct blkcg *blkcg = css_to_blkcg(css);
+ struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
+ struct blkcg_gq *blkg;
+ int ret = -ERANGE;
+
+ if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
+ return ret;
+
+ ret = 0;
+ spin_lock_irq(&blkcg->lock);
+ bfqgd->weight = (unsigned short)val;
+ hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
+ struct bfq_group *bfqg = blkg_to_bfqg(blkg);
+
+ if (!bfqg)
+ continue;
+ /*
+ * Setting the prio_changed flag of the entity
+ * to 1 with new_weight == weight would re-set
+ * the value of the weight to its ioprio mapping.
+ * Set the flag only if necessary.
+ */
+ if ((unsigned short)val != bfqg->entity.new_weight) {
+ bfqg->entity.new_weight = (unsigned short)val;
+ /*
+ * Make sure that the above new value has been
+ * stored in bfqg->entity.new_weight before
+ * setting the prio_changed flag. In fact,
+ * this flag may be read asynchronously (in
+ * critical sections protected by a different
+ * lock than that held here), and finding this
+ * flag set may cause the execution of the code
+ * for updating parameters whose value may
+ * depend also on bfqg->entity.new_weight (in
+ * __bfq_entity_update_weight_prio).
+ * This barrier makes sure that the new value
+ * of bfqg->entity.new_weight is correctly
+ * seen in that code.
+ */
+ smp_wmb();
+ bfqg->entity.prio_changed = 1;
+ }
+ }
+ spin_unlock_irq(&blkcg->lock);
+
+ return ret;
+}
+
+static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ u64 weight;
+ /* First unsigned long found in the file is used */
+ int ret = kstrtoull(strim(buf), 0, &weight);
+
+ if (ret)
+ return ret;
+
+ return bfq_io_set_weight_legacy(of_css(of), NULL, weight);
+}
+
+static int bfqg_print_stat(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
+ &blkcg_policy_bfq, seq_cft(sf)->private, false);
+ return 0;
+}
+
+static int bfqg_print_rwstat(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
+ &blkcg_policy_bfq, seq_cft(sf)->private, true);
+ return 0;
+}
+
+static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
+ struct blkg_policy_data *pd, int off)
+{
+ u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
+ &blkcg_policy_bfq, off);
+ return __blkg_prfill_u64(sf, pd, sum);
+}
+
+static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
+ struct blkg_policy_data *pd, int off)
+{
+ struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
+ &blkcg_policy_bfq,
+ off);
+ return __blkg_prfill_rwstat(sf, pd, &sum);
+}
+
+static int bfqg_print_stat_recursive(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+ bfqg_prfill_stat_recursive, &blkcg_policy_bfq,
+ seq_cft(sf)->private, false);
+ return 0;
+}
+
+static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+ bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq,
+ seq_cft(sf)->private, true);
+ return 0;
+}
+
+static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
+ int off)
+{
+ u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
+
+ return __blkg_prfill_u64(sf, pd, sum >> 9);
+}
+
+static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+ bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false);
+ return 0;
+}
+
+static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
+ struct blkg_policy_data *pd, int off)
+{
+ struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
+ offsetof(struct blkcg_gq, stat_bytes));
+ u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
+ atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
+
+ return __blkg_prfill_u64(sf, pd, sum >> 9);
+}
+
+static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+ bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0,
+ false);
+ return 0;
+}
+
+
+static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
+ struct blkg_policy_data *pd, int off)
+{
+ struct bfq_group *bfqg = pd_to_bfqg(pd);
+ u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples);
+ u64 v = 0;
+
+ if (samples) {
+ v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum);
+ v = div64_u64(v, samples);
+ }
+ __blkg_prfill_u64(sf, pd, v);
+ return 0;
+}
+
+/* print avg_queue_size */
+static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+ bfqg_prfill_avg_queue_size, &blkcg_policy_bfq,
+ 0, false);
+ return 0;
+}
+
+static struct bfq_group *
+bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
+{
+ int ret;
+
+ ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq);
+ if (ret)
+ return NULL;
+
+ return blkg_to_bfqg(bfqd->queue->root_blkg);
+}
+
+static struct cftype bfq_blkcg_legacy_files[] = {
+ {
+ .name = "bfq.weight",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = bfq_io_show_weight,
+ .write_u64 = bfq_io_set_weight_legacy,
+ },
+
+ /* statistics, covers only the tasks in the bfqg */
+ {
+ .name = "bfq.time",
+ .private = offsetof(struct bfq_group, stats.time),
+ .seq_show = bfqg_print_stat,
+ },
+ {
+ .name = "bfq.sectors",
+ .seq_show = bfqg_print_stat_sectors,
+ },
+ {
+ .name = "bfq.io_service_bytes",
+ .private = (unsigned long)&blkcg_policy_bfq,
+ .seq_show = blkg_print_stat_bytes,
+ },
+ {
+ .name = "bfq.io_serviced",
+ .private = (unsigned long)&blkcg_policy_bfq,
+ .seq_show = blkg_print_stat_ios,
+ },
+ {
+ .name = "bfq.io_service_time",
+ .private = offsetof(struct bfq_group, stats.service_time),
+ .seq_show = bfqg_print_rwstat,
+ },
+ {
+ .name = "bfq.io_wait_time",
+ .private = offsetof(struct bfq_group, stats.wait_time),
+ .seq_show = bfqg_print_rwstat,
+ },
+ {
+ .name = "bfq.io_merged",
+ .private = offsetof(struct bfq_group, stats.merged),
+ .seq_show = bfqg_print_rwstat,
+ },
+ {
+ .name = "bfq.io_queued",
+ .private = offsetof(struct bfq_group, stats.queued),
+ .seq_show = bfqg_print_rwstat,
+ },
+
+ /* the same statictics which cover the bfqg and its descendants */
+ {
+ .name = "bfq.time_recursive",
+ .private = offsetof(struct bfq_group, stats.time),
+ .seq_show = bfqg_print_stat_recursive,
+ },
+ {
+ .name = "bfq.sectors_recursive",
+ .seq_show = bfqg_print_stat_sectors_recursive,
+ },
+ {
+ .name = "bfq.io_service_bytes_recursive",
+ .private = (unsigned long)&blkcg_policy_bfq,
+ .seq_show = blkg_print_stat_bytes_recursive,
+ },
+ {
+ .name = "bfq.io_serviced_recursive",
+ .private = (unsigned long)&blkcg_policy_bfq,
+ .seq_show = blkg_print_stat_ios_recursive,
+ },
+ {
+ .name = "bfq.io_service_time_recursive",
+ .private = offsetof(struct bfq_group, stats.service_time),
+ .seq_show = bfqg_print_rwstat_recursive,
+ },
+ {
+ .name = "bfq.io_wait_time_recursive",
+ .private = offsetof(struct bfq_group, stats.wait_time),
+ .seq_show = bfqg_print_rwstat_recursive,
+ },
+ {
+ .name = "bfq.io_merged_recursive",
+ .private = offsetof(struct bfq_group, stats.merged),
+ .seq_show = bfqg_print_rwstat_recursive,
+ },
+ {
+ .name = "bfq.io_queued_recursive",
+ .private = offsetof(struct bfq_group, stats.queued),
+ .seq_show = bfqg_print_rwstat_recursive,
+ },
+ {
+ .name = "bfq.avg_queue_size",
+ .seq_show = bfqg_print_avg_queue_size,
+ },
+ {
+ .name = "bfq.group_wait_time",
+ .private = offsetof(struct bfq_group, stats.group_wait_time),
+ .seq_show = bfqg_print_stat,
+ },
+ {
+ .name = "bfq.idle_time",
+ .private = offsetof(struct bfq_group, stats.idle_time),
+ .seq_show = bfqg_print_stat,
+ },
+ {
+ .name = "bfq.empty_time",
+ .private = offsetof(struct bfq_group, stats.empty_time),
+ .seq_show = bfqg_print_stat,
+ },
+ {
+ .name = "bfq.dequeue",
+ .private = offsetof(struct bfq_group, stats.dequeue),
+ .seq_show = bfqg_print_stat,
+ },
+ { } /* terminate */
+};
+
+static struct cftype bfq_blkg_files[] = {
+ {
+ .name = "bfq.weight",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = bfq_io_show_weight,
+ .write = bfq_io_set_weight,
+ },
+ {} /* terminate */
+};
+
+#else /* CONFIG_BFQ_GROUP_IOSCHED */
+
+static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg,
+ struct bfq_queue *bfqq, int op, int op_flags) { }
+static inline void
+bfqg_stats_update_io_remove(struct bfq_group *bfqg, int op, int op_flags) { }
+static inline void
+bfqg_stats_update_io_merged(struct bfq_group *bfqg, int op, int op_flags) { }
+static inline void bfqg_stats_update_completion(struct bfq_group *bfqg,
+ uint64_t start_time, uint64_t io_start_time, int op,
+ int op_flags) { }
+static inline void
+bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
+ struct bfq_group *curr_bfqg) { }
+static inline void bfqg_stats_end_empty_time(struct bfqg_stats *stats) { }
+static inline void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
+static inline void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
+static inline void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }
+static inline void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
+static inline void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { }
+
+static void bfq_init_entity(struct bfq_entity *entity,
+ struct bfq_group *bfqg)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ entity->weight = entity->new_weight;
+ entity->orig_weight = entity->new_weight;
+ if (bfqq) {
+ bfqq->ioprio = bfqq->new_ioprio;
+ bfqq->ioprio_class = bfqq->new_ioprio_class;
+ }
+ entity->sched_data = &bfqg->sched_data;
+}
+
+static struct bfq_group *
+bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
+{
+ struct bfq_data *bfqd = bic_to_bfqd(bic);
+
+ return bfqd->root_group;
+}
+
+static void bfq_end_wr_async(struct bfq_data *bfqd)
+{
+ bfq_end_wr_async_queues(bfqd, bfqd->root_group);
+}
+
+static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
+ struct blkcg *blkcg)
+{
+ return bfqd->root_group;
+}
+
+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
+{
+ return bfqq->bfqd->root_group;
+}
+
+static struct bfq_group *
+bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
+{
+ struct bfq_group *bfqg;
+ int i;
+
+ bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
+ if (!bfqg)
+ return NULL;
+
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
+
+ return bfqg;
+}
+#endif
diff -ruN linux-4.8/block/bfq.h linux-bfq-bfq-v8/block/bfq.h
--- linux-4.8/block/bfq.h 1970-01-01 00:00:00.000000000 +0000
+++ linux-bfq-bfq-v8/block/bfq.h 2016-10-06 07:08:26.000000000 +0000
@@ -0,0 +1,870 @@
+/*
+ * BFQ-v8r3 for 4.8.0: data structures and common functions prototypes.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org>
+ */
+
+#ifndef _BFQ_H
+#define _BFQ_H
+
+#include <linux/blktrace_api.h>
+#include <linux/hrtimer.h>
+#include <linux/ioprio.h>
+#include <linux/rbtree.h>
+#include <linux/blk-cgroup.h>
+
+#define BFQ_IOPRIO_CLASSES 3
+#define BFQ_CL_IDLE_TIMEOUT (HZ/5)
+
+#define BFQ_MIN_WEIGHT 1
+#define BFQ_MAX_WEIGHT 1000
+#define BFQ_WEIGHT_CONVERSION_COEFF 10
+
+#define BFQ_DEFAULT_QUEUE_IOPRIO 4
+
+#define BFQ_WEIGHT_LEGACY_DFL 100
+#define BFQ_DEFAULT_GRP_IOPRIO 0
+#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE
+
+/*
+ * Soft real-time applications are extremely more latency sensitive
+ * than interactive ones. Over-raise the weight of the former to
+ * privilege them against the latter.
+ */
+#define BFQ_SOFTRT_WEIGHT_FACTOR 100
+
+struct bfq_entity;
+
+/**
+ * struct bfq_service_tree - per ioprio_class service tree.
+ *
+ * Each service tree represents a B-WF2Q+ scheduler on its own. Each
+ * ioprio_class has its own independent scheduler, and so its own
+ * bfq_service_tree. All the fields are protected by the queue lock
+ * of the containing bfqd.
+ */
+struct bfq_service_tree {
+ /* tree for active entities (i.e., those backlogged) */
+ struct rb_root active;
+ /* tree for idle entities (i.e., not backlogged, with V <= F_i)*/
+ struct rb_root idle;
+
+ struct bfq_entity *first_idle; /* idle entity with minimum F_i */
+ struct bfq_entity *last_idle; /* idle entity with maximum F_i */
+
+ u64 vtime; /* scheduler virtual time */
+ /* scheduler weight sum; active and idle entities contribute to it */
+ unsigned long wsum;
+};
+
+/**
+ * struct bfq_sched_data - multi-class scheduler.
+ *
+ * bfq_sched_data is the basic scheduler queue. It supports three
+ * ioprio_classes, and can be used either as a toplevel queue or as an
+ * intermediate queue on a hierarchical setup. @next_in_service
+ * points to the active entity of the sched_data service trees that
+ * will be scheduled next. It is used to reduce the number of steps
+ * needed for each hierarchical-schedule update.
+ *
+ * The supported ioprio_classes are the same as in CFQ, in descending
+ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
+ * Requests from higher priority queues are served before all the
+ * requests from lower priority queues; among requests of the same
+ * queue requests are served according to B-WF2Q+.
+ * All the fields are protected by the queue lock of the containing bfqd.
+ */
+struct bfq_sched_data {
+ struct bfq_entity *in_service_entity; /* entity in service */
+ /* head-of-the-line entity in the scheduler (see comments above) */
+ struct bfq_entity *next_in_service;
+ /* array of service trees, one per ioprio_class */
+ struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
+};
+
+/**
+ * struct bfq_weight_counter - counter of the number of all active entities
+ * with a given weight.
+ */
+struct bfq_weight_counter {
+ unsigned int weight; /* weight of the entities this counter refers to */
+ unsigned int num_active; /* nr of active entities with this weight */
+ /*
+ * Weights tree member (see bfq_data's @queue_weights_tree and
+ * @group_weights_tree)
+ */
+ struct rb_node weights_node;
+};
+
+/**
+ * struct bfq_entity - schedulable entity.
+ *
+ * A bfq_entity is used to represent either a bfq_queue (leaf node in the
+ * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each
+ * entity belongs to the sched_data of the parent group in the cgroup
+ * hierarchy. Non-leaf entities have also their own sched_data, stored
+ * in @my_sched_data.
+ *
+ * Each entity stores independently its priority values; this would
+ * allow different weights on different devices, but this
+ * functionality is not exported to userspace by now. Priorities and
+ * weights are updated lazily, first storing the new values into the
+ * new_* fields, then setting the @prio_changed flag. As soon as
+ * there is a transition in the entity state that allows the priority
+ * update to take place the effective and the requested priority
+ * values are synchronized.
+ *
+ * Unless cgroups are used, the weight value is calculated from the
+ * ioprio to export the same interface as CFQ. When dealing with
+ * ``well-behaved'' queues (i.e., queues that do not spend too much
+ * time to consume their budget and have true sequential behavior, and
+ * when there are no external factors breaking anticipation) the
+ * relative weights at each level of the cgroups hierarchy should be
+ * guaranteed. All the fields are protected by the queue lock of the
+ * containing bfqd.
+ */
+struct bfq_entity {
+ struct rb_node rb_node; /* service_tree member */
+ /* pointer to the weight counter associated with this entity */
+ struct bfq_weight_counter *weight_counter;
+
+ /*
+ * flag, true if the entity is on a tree (either the active or
+ * the idle one of its service_tree).
+ */
+ int on_st;
+
+ u64 finish; /* B-WF2Q+ finish timestamp (aka F_i) */
+ u64 start; /* B-WF2Q+ start timestamp (aka S_i) */
+
+ /* tree the entity is enqueued into; %NULL if not on a tree */
+ struct rb_root *tree;
+
+ /*
+ * minimum start time of the (active) subtree rooted at this
+ * entity; used for O(log N) lookups into active trees
+ */
+ u64 min_start;
+
+ /* amount of service received during the last service slot */
+ int service;
+
+ /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
+ int budget;
+
+ unsigned int weight; /* weight of the queue */
+ unsigned int new_weight; /* next weight if a change is in progress */
+
+ /* original weight, used to implement weight boosting */
+ unsigned int orig_weight;
+
+ /* parent entity, for hierarchical scheduling */
+ struct bfq_entity *parent;
+
+ /*
+ * For non-leaf nodes in the hierarchy, the associated
+ * scheduler queue, %NULL on leaf nodes.
+ */
+ struct bfq_sched_data *my_sched_data;
+ /* the scheduler queue this entity belongs to */
+ struct bfq_sched_data *sched_data;
+
+ /* flag, set to request a weight, ioprio or ioprio_class change */
+ int prio_changed;
+};
+
+struct bfq_group;
+
+/**
+ * struct bfq_queue - leaf schedulable entity.
+ *
+ * A bfq_queue is a leaf request queue; it can be associated with an
+ * io_context or more, if it is async or shared between cooperating
+ * processes. @cgroup holds a reference to the cgroup, to be sure that it
+ * does not disappear while a bfqq still references it (mostly to avoid
+ * races between request issuing and task migration followed by cgroup
+ * destruction).
+ * All the fields are protected by the queue lock of the containing bfqd.
+ */
+struct bfq_queue {
+ /* reference counter */
+ int ref;
+ /* parent bfq_data */
+ struct bfq_data *bfqd;
+
+ /* current ioprio and ioprio class */
+ unsigned short ioprio, ioprio_class;
+ /* next ioprio and ioprio class if a change is in progress */
+ unsigned short new_ioprio, new_ioprio_class;
+
+ /*
+ * Shared bfq_queue if queue is cooperating with one or more
+ * other queues.
+ */
+ struct bfq_queue *new_bfqq;
+ /* request-position tree member (see bfq_group's @rq_pos_tree) */
+ struct rb_node pos_node;
+ /* request-position tree root (see bfq_group's @rq_pos_tree) */
+ struct rb_root *pos_root;
+
+ /* sorted list of pending requests */
+ struct rb_root sort_list;
+ /* if fifo isn't expired, next request to serve */
+ struct request *next_rq;
+ /* number of sync and async requests queued */
+ int queued[2];
+ /* number of sync and async requests currently allocated */
+ int allocated[2];
+ /* number of pending metadata requests */
+ int meta_pending;
+ /* fifo list of requests in sort_list */
+ struct list_head fifo;
+
+ /* entity representing this queue in the scheduler */
+ struct bfq_entity entity;
+
+ /* maximum budget allowed from the feedback mechanism */
+ int max_budget;
+ /* budget expiration (in jiffies) */
+ unsigned long budget_timeout;
+
+ /* number of requests on the dispatch list or inside driver */
+ int dispatched;
+
+ unsigned int flags; /* status flags.*/
+
+ /* node for active/idle bfqq list inside parent bfqd */
+ struct list_head bfqq_list;
+
+ /* bit vector: a 1 for each seeky requests in history */
+ u32 seek_history;
+
+ /* node for the device's burst list */
+ struct hlist_node burst_list_node;
+
+ /* position of the last request enqueued */
+ sector_t last_request_pos;
+
+ /* Number of consecutive pairs of request completion and
+ * arrival, such that the queue becomes idle after the
+ * completion, but the next request arrives within an idle
+ * time slice; used only if the queue's IO_bound flag has been
+ * cleared.
+ */
+ unsigned int requests_within_timer;
+
+ /* pid of the process owning the queue, used for logging purposes */
+ pid_t pid;
+
+ /*
+ * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
+ * if the queue is shared.
+ */
+ struct bfq_io_cq *bic;
+
+ /* current maximum weight-raising time for this queue */
+ unsigned long wr_cur_max_time;
+ /*
+ * Minimum time instant such that, only if a new request is
+ * enqueued after this time instant in an idle @bfq_queue with
+ * no outstanding requests, then the task associated with the
+ * queue it is deemed as soft real-time (see the comments on
+ * the function bfq_bfqq_softrt_next_start())
+ */
+ unsigned long soft_rt_next_start;
+ /*
+ * Start time of the current weight-raising period if
+ * the @bfq-queue is being weight-raised, otherwise
+ * finish time of the last weight-raising period.
+ */
+ unsigned long last_wr_start_finish;
+ /* factor by which the weight of this queue is multiplied */
+ unsigned int wr_coeff;
+ /*
+ * Time of the last transition of the @bfq_queue from idle to
+ * backlogged.
+ */
+ unsigned long last_idle_bklogged;
+ /*
+ * Cumulative service received from the @bfq_queue since the
+ * last transition from idle to backlogged.
+ */
+ unsigned long service_from_backlogged;
+
+ unsigned long split_time; /* time of last split */
+};
+
+/**
+ * struct bfq_ttime - per process thinktime stats.
+ */
+struct bfq_ttime {
+ u64 last_end_request; /* completion time of last request */
+
+ u64 ttime_total; /* total process thinktime */
+ unsigned long ttime_samples; /* number of thinktime samples */
+ u64 ttime_mean; /* average process thinktime */
+
+};
+
+/**
+ * struct bfq_io_cq - per (request_queue, io_context) structure.
+ */
+struct bfq_io_cq {
+ /* associated io_cq structure */
+ struct io_cq icq; /* must be the first member */
+ /* array of two process queues, the sync and the async */
+ struct bfq_queue *bfqq[2];
+ /* associated @bfq_ttime struct */
+ struct bfq_ttime ttime;
+ /* per (request_queue, blkcg) ioprio */
+ int ioprio;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ uint64_t blkcg_serial_nr; /* the current blkcg serial */
+#endif
+
+ /*
+ * Snapshot of the idle window before merging; taken to
+ * remember this value while the queue is merged, so as to be
+ * able to restore it in case of split.
+ */
+ bool saved_idle_window;
+ /*
+ * Same purpose as the previous two fields for the I/O bound
+ * classification of a queue.
+ */
+ bool saved_IO_bound;
+
+ /*
+ * Same purpose as the previous fields for the value of the
+ * field keeping the queue's belonging to a large burst
+ */
+ bool saved_in_large_burst;
+ /*
+ * True if the queue belonged to a burst list before its merge
+ * with another cooperating queue.
+ */
+ bool was_in_burst_list;
+};
+
+enum bfq_device_speed {
+ BFQ_BFQD_FAST,
+ BFQ_BFQD_SLOW,
+};
+
+/**
+ * struct bfq_data - per-device data structure.
+ *
+ * All the fields are protected by the @queue lock.
+ */
+struct bfq_data {
+ /* request queue for the device */
+ struct request_queue *queue;
+
+ /* root bfq_group for the device */
+ struct bfq_group *root_group;
+
+ /*
+ * rbtree of weight counters of @bfq_queues, sorted by
+ * weight. Used to keep track of whether all @bfq_queues have
+ * the same weight. The tree contains one counter for each
+ * distinct weight associated to some active and not
+ * weight-raised @bfq_queue (see the comments to the functions
+ * bfq_weights_tree_[add|remove] for further details).
+ */
+ struct rb_root queue_weights_tree;
+ /*
+ * rbtree of non-queue @bfq_entity weight counters, sorted by
+ * weight. Used to keep track of whether all @bfq_groups have
+ * the same weight. The tree contains one counter for each
+ * distinct weight associated to some active @bfq_group (see
+ * the comments to the functions bfq_weights_tree_[add|remove]
+ * for further details).
+ */
+ struct rb_root group_weights_tree;
+
+ /*
+ * Number of bfq_queues containing requests (including the
+ * queue in service, even if it is idling).
+ */
+ int busy_queues;
+ /* number of weight-raised busy @bfq_queues */
+ int wr_busy_queues;
+ /* number of queued requests */
+ int queued;
+ /* number of requests dispatched and waiting for completion */
+ int rq_in_driver;
+
+ /*
+ * Maximum number of requests in driver in the last
+ * @hw_tag_samples completed requests.
+ */
+ int max_rq_in_driver;
+ /* number of samples used to calculate hw_tag */
+ int hw_tag_samples;
+ /* flag set to one if the driver is showing a queueing behavior */
+ int hw_tag;
+
+ /* number of budgets assigned */
+ int budgets_assigned;
+
+ /*
+ * Timer set when idling (waiting) for the next request from
+ * the queue in service.
+ */
+ struct hrtimer idle_slice_timer;
+ /* delayed work to restart dispatching on the request queue */
+ struct work_struct unplug_work;
+
+ /* bfq_queue in service */
+ struct bfq_queue *in_service_queue;
+ /* bfq_io_cq (bic) associated with the @in_service_queue */
+ struct bfq_io_cq *in_service_bic;
+
+ /* on-disk position of the last served request */
+ sector_t last_position;
+
+ u64 last_completion;
+
+ /* time of first request dispatch in probing window */
+ u64 first_dispatch;
+ /* time of last dispatch */
+ u64 last_dispatch;
+
+ /* beginning of the last budget */
+ ktime_t last_budget_start;
+ /* beginning of the last idle slice */
+ ktime_t last_idling_start;
+ /* number of samples in last window */
+ int peak_rate_samples;
+ /* number of samples of seq dispatches in last window */
+ u32 sequential_samples;
+ /* total number of sectors transferred during last window */
+ u64 tot_sectors_dispatched;
+ /* Time elapsed from first dispatch in sampling window */
+ u32 delta_from_first_us;
+ /* peak transfer rate observed for a budget */
+ u64 peak_rate;
+ /* maximum budget allotted to a bfq_queue before rescheduling */
+ int bfq_max_budget;
+
+ /* list of all the bfq_queues active on the device */
+ struct list_head active_list;
+ /* list of all the bfq_queues idle on the device */
+ struct list_head idle_list;
+
+ /*
+ * Timeout for async/sync requests; when it fires, requests
+ * are served in fifo order.
+ */
+ u64 bfq_fifo_expire[2];
+ /* weight of backward seeks wrt forward ones */
+ unsigned int bfq_back_penalty;
+ /* maximum allowed backward seek */
+ unsigned int bfq_back_max;
+ /* maximum idling time */
+ u64 bfq_slice_idle;
+ /* last time CLASS_IDLE was served */
+ u64 bfq_class_idle_last_service;
+
+ /* user-configured max budget value (0 for auto-tuning) */
+ int bfq_user_max_budget;
+ /*
+ * Timeout for bfq_queues to consume their budget; used to
+ * prevent seeky queues from imposing long latencies to
+ * sequential or quasi-sequential ones (this also implies that
+ * seeky queues cannot receive guarantees in the service
+ * domain; after a timeout they are charged for the time they
+ * have been in service, to preserve fairness among them, but
+ * without service-domain guarantees).
+ */
+ unsigned int bfq_timeout;
+
+ /*
+ * Number of consecutive requests that must be issued within
+ * the idle time slice to set again idling to a queue which
+ * was marked as non-I/O-bound (see the definition of the
+ * IO_bound flag for further details).
+ */
+ unsigned int bfq_requests_within_timer;
+
+ /*
+ * Force device idling whenever needed to provide accurate
+ * service guarantees, without caring about throughput
+ * issues. CAVEAT: this may even increase latencies, in case
+ * of useless idling for processes that did stop doing I/O.
+ */
+ bool strict_guarantees;
+
+ /*
+ * Last time at which a queue entered the current burst of
+ * queues being activated shortly after each other; for more
+ * details about this and the following parameters related to
+ * a burst of activations, see the comments on the function
+ * bfq_handle_burst.
+ */
+ unsigned long last_ins_in_burst;
+ /*
+ * Reference time interval used to decide whether a queue has
+ * been activated shortly after @last_ins_in_burst.
+ */
+ unsigned long bfq_burst_interval;
+ /* number of queues in the current burst of queue activations */
+ int burst_size;
+
+ /* common parent entity for the queues in the burst */
+ struct bfq_entity *burst_parent_entity;
+ /* Maximum burst size above which the current queue-activation
+ * burst is deemed as 'large'.
+ */
+ unsigned long bfq_large_burst_thresh;
+ /* true if a large queue-activation burst is in progress */
+ bool large_burst;
+ /*
+ * Head of the burst list (as for the above fields, more
+ * details in the comments on the function bfq_handle_burst).
+ */
+ struct hlist_head burst_list;
+
+ /* if set to true, low-latency heuristics are enabled */
+ bool low_latency;
+ /*
+ * Maximum factor by which the weight of a weight-raised queue
+ * is multiplied.
+ */
+ unsigned int bfq_wr_coeff;
+ /* maximum duration of a weight-raising period (jiffies) */
+ unsigned int bfq_wr_max_time;
+
+ /* Maximum weight-raising duration for soft real-time processes */
+ unsigned int bfq_wr_rt_max_time;
+ /*
+ * Minimum idle period after which weight-raising may be
+ * reactivated for a queue (in jiffies).
+ */
+ unsigned int bfq_wr_min_idle_time;
+ /*
+ * Minimum period between request arrivals after which
+ * weight-raising may be reactivated for an already busy async
+ * queue (in jiffies).
+ */
+ unsigned long bfq_wr_min_inter_arr_async;
+
+ /* Max service-rate for a soft real-time queue, in sectors/sec */
+ unsigned int bfq_wr_max_softrt_rate;
+ /*
+ * Cached value of the product R*T, used for computing the
+ * maximum duration of weight raising automatically.
+ */
+ u64 RT_prod;
+ /* device-speed class for the low-latency heuristic */
+ enum bfq_device_speed device_speed;
+
+ /* fallback dummy bfqq for extreme OOM conditions */
+ struct bfq_queue oom_bfqq;
+};
+
+enum bfqq_state_flags {
+ BFQ_BFQQ_FLAG_just_created = 0, /* queue just allocated */
+ BFQ_BFQQ_FLAG_busy, /* has requests or is in service */
+ BFQ_BFQQ_FLAG_wait_request, /* waiting for a request */
+ BFQ_BFQQ_FLAG_non_blocking_wait_rq, /*
+ * waiting for a request
+ * without idling the device
+ */
+ BFQ_BFQQ_FLAG_must_alloc, /* must be allowed rq alloc */
+ BFQ_BFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
+ BFQ_BFQQ_FLAG_idle_window, /* slice idling enabled */
+ BFQ_BFQQ_FLAG_sync, /* synchronous queue */
+ BFQ_BFQQ_FLAG_IO_bound, /*
+ * bfqq has timed-out at least once
+ * having consumed at most 2/10 of
+ * its budget
+ */
+ BFQ_BFQQ_FLAG_in_large_burst, /*
+ * bfqq activated in a large burst,
+ * see comments to bfq_handle_burst.
+ */
+ BFQ_BFQQ_FLAG_softrt_update, /*
+ * may need softrt-next-start
+ * update
+ */
+ BFQ_BFQQ_FLAG_coop, /* bfqq is shared */
+ BFQ_BFQQ_FLAG_split_coop /* shared bfqq will be split */
+};
+
+#define BFQ_BFQQ_FNS(name) \
+static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \
+{ \
+ (bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name); \
+} \
+static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \
+{ \
+ (bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name); \
+} \
+static int bfq_bfqq_##name(const struct bfq_queue *bfqq) \
+{ \
+ return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0; \
+}
+
+BFQ_BFQQ_FNS(just_created);
+BFQ_BFQQ_FNS(busy);
+BFQ_BFQQ_FNS(wait_request);
+BFQ_BFQQ_FNS(non_blocking_wait_rq);
+BFQ_BFQQ_FNS(must_alloc);
+BFQ_BFQQ_FNS(fifo_expire);
+BFQ_BFQQ_FNS(idle_window);
+BFQ_BFQQ_FNS(sync);
+BFQ_BFQQ_FNS(IO_bound);
+BFQ_BFQQ_FNS(in_large_burst);
+BFQ_BFQQ_FNS(coop);
+BFQ_BFQQ_FNS(split_coop);
+BFQ_BFQQ_FNS(softrt_update);
+#undef BFQ_BFQQ_FNS
+
+/* Logging facilities. */
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
+
+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
+ char __pbuf[128]; \
+ \
+ assert_spin_locked((bfqd)->queue->queue_lock); \
+ blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
+ blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, \
+ (bfqq)->pid, \
+ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \
+ __pbuf, ##args); \
+} while (0)
+
+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \
+ char __pbuf[128]; \
+ \
+ blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf)); \
+ blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args); \
+} while (0)
+
+#else /* CONFIG_BFQ_GROUP_IOSCHED */
+
+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \
+ blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid, \
+ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \
+ ##args)
+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0)
+
+#endif /* CONFIG_BFQ_GROUP_IOSCHED */
+
+#define bfq_log(bfqd, fmt, args...) \
+ blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
+
+/* Expiration reasons. */
+enum bfqq_expiration {
+ BFQ_BFQQ_TOO_IDLE = 0, /*
+ * queue has been idling for
+ * too long
+ */
+ BFQ_BFQQ_BUDGET_TIMEOUT, /* budget took too long to be used */
+ BFQ_BFQQ_BUDGET_EXHAUSTED, /* budget consumed */
+ BFQ_BFQQ_NO_MORE_REQUESTS, /* the queue has no more requests */
+ BFQ_BFQQ_PREEMPTED /* preemption in progress */
+};
+
+
+struct bfqg_stats {
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ /* number of ios merged */
+ struct blkg_rwstat merged;
+ /* total time spent on device in ns, may not be accurate w/ queueing */
+ struct blkg_rwstat service_time;
+ /* total time spent waiting in scheduler queue in ns */
+ struct blkg_rwstat wait_time;
+ /* number of IOs queued up */
+ struct blkg_rwstat queued;
+ /* total disk time and nr sectors dispatched by this group */
+ struct blkg_stat time;
+ /* sum of number of ios queued across all samples */
+ struct blkg_stat avg_queue_size_sum;
+ /* count of samples taken for average */
+ struct blkg_stat avg_queue_size_samples;
+ /* how many times this group has been removed from service tree */
+ struct blkg_stat dequeue;
+ /* total time spent waiting for it to be assigned a timeslice. */
+ struct blkg_stat group_wait_time;
+ /* time spent idling for this blkcg_gq */
+ struct blkg_stat idle_time;
+ /* total time with empty current active q with other requests queued */
+ struct blkg_stat empty_time;
+ /* fields after this shouldn't be cleared on stat reset */
+ uint64_t start_group_wait_time;
+ uint64_t start_idle_time;
+ uint64_t start_empty_time;
+ uint16_t flags;
+#endif
+};
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+/*
+ * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
+ *
+ * @ps: @blkcg_policy_storage that this structure inherits
+ * @weight: weight of the bfq_group
+ */
+struct bfq_group_data {
+ /* must be the first member */
+ struct blkcg_policy_data pd;
+
+ unsigned int weight;
+};
+
+/**
+ * struct bfq_group - per (device, cgroup) data structure.
+ * @entity: schedulable entity to insert into the parent group sched_data.
+ * @sched_data: own sched_data, to contain child entities (they may be
+ * both bfq_queues and bfq_groups).
+ * @bfqd: the bfq_data for the device this group acts upon.
+ * @async_bfqq: array of async queues for all the tasks belonging to
+ * the group, one queue per ioprio value per ioprio_class,
+ * except for the idle class that has only one queue.
+ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
+ * @my_entity: pointer to @entity, %NULL for the toplevel group; used
+ * to avoid too many special cases during group creation/
+ * migration.
+ * @active_entities: number of active entities belonging to the group;
+ * unused for the root group. Used to know whether there
+ * are groups with more than one active @bfq_entity
+ * (see the comments to the function
+ * bfq_bfqq_may_idle()).
+ * @rq_pos_tree: rbtree sorted by next_request position, used when
+ * determining if two or more queues have interleaving
+ * requests (see bfq_find_close_cooperator()).
+ *
+ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
+ * there is a set of bfq_groups, each one collecting the lower-level
+ * entities belonging to the group that are acting on the same device.
+ *
+ * Locking works as follows:
+ * o @bfqd is protected by the queue lock, RCU is used to access it
+ * from the readers.
+ * o All the other fields are protected by the @bfqd queue lock.
+ */
+struct bfq_group {
+ /* must be the first member */
+ struct blkg_policy_data pd;
+
+ struct bfq_entity entity;
+ struct bfq_sched_data sched_data;
+
+ void *bfqd;
+
+ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
+ struct bfq_queue *async_idle_bfqq;
+
+ struct bfq_entity *my_entity;
+
+ int active_entities;
+
+ struct rb_root rq_pos_tree;
+
+ struct bfqg_stats stats;
+};
+
+#else
+struct bfq_group {
+ struct bfq_sched_data sched_data;
+
+ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
+ struct bfq_queue *async_idle_bfqq;
+
+ struct rb_root rq_pos_tree;
+};
+#endif
+
+static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
+
+static struct bfq_service_tree *
+bfq_entity_service_tree(struct bfq_entity *entity)
+{
+ struct bfq_sched_data *sched_data = entity->sched_data;
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ unsigned int idx = bfqq ? bfqq->ioprio_class - 1 :
+ BFQ_DEFAULT_GRP_CLASS - 1;
+
+ BUG_ON(idx >= BFQ_IOPRIO_CLASSES);
+ BUG_ON(sched_data == NULL);
+
+ if (bfqq)
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "entity_service_tree %p %d",
+ sched_data->service_tree + idx, idx);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else {
+ struct bfq_group *bfqg =
+ container_of(entity, struct bfq_group, entity);
+
+ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
+ "entity_service_tree %p %d",
+ sched_data->service_tree + idx, idx);
+ }
+#endif
+ return sched_data->service_tree + idx;
+}
+
+static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync)
+{
+ return bic->bfqq[is_sync];
+}
+
+static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq,
+ bool is_sync)
+{
+ bic->bfqq[is_sync] = bfqq;
+}
+
+static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic)
+{
+ return bic->icq.q->elevator->elevator_data;
+}
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+
+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
+{
+ struct bfq_entity *group_entity = bfqq->entity.parent;
+
+ if (!group_entity)
+ group_entity = &bfqq->bfqd->root_group->entity;
+
+ return container_of(group_entity, struct bfq_group, entity);
+}
+
+#else
+
+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
+{
+ return bfqq->bfqd->root_group;
+}
+
+#endif
+
+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio);
+static void bfq_put_queue(struct bfq_queue *bfqq);
+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq);
+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
+ struct bio *bio, bool is_sync,
+ struct bfq_io_cq *bic);
+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
+ struct bfq_group *bfqg);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
+#endif
+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
+
+#endif /* _BFQ_H */
diff -ruN linux-4.8/block/bfq-ioc.c linux-bfq-bfq-v8/block/bfq-ioc.c
--- linux-4.8/block/bfq-ioc.c 1970-01-01 00:00:00.000000000 +0000
+++ linux-bfq-bfq-v8/block/bfq-ioc.c 2016-10-06 07:08:26.000000000 +0000
@@ -0,0 +1,36 @@
+/*
+ * BFQ: I/O context handling.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ */
+
+/**
+ * icq_to_bic - convert iocontext queue structure to bfq_io_cq.
+ * @icq: the iocontext queue.
+ */
+static struct bfq_io_cq *icq_to_bic(struct io_cq *icq)
+{
+ /* bic->icq is the first member, %NULL will convert to %NULL */
+ return container_of(icq, struct bfq_io_cq, icq);
+}
+
+/**
+ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd.
+ * @bfqd: the lookup key.
+ * @ioc: the io_context of the process doing I/O.
+ *
+ * Queue lock must be held.
+ */
+static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
+ struct io_context *ioc)
+{
+ if (ioc)
+ return icq_to_bic(ioc_lookup_icq(ioc, bfqd->queue));
+ return NULL;
+}
diff -ruN linux-4.8/block/bfq-iosched.c linux-bfq-bfq-v8/block/bfq-iosched.c
--- linux-4.8/block/bfq-iosched.c 1970-01-01 00:00:00.000000000 +0000
+++ linux-bfq-bfq-v8/block/bfq-iosched.c 2016-10-06 07:08:26.000000000 +0000
@@ -0,0 +1,5057 @@
+/*
+ * Budget Fair Queueing (BFQ) disk scheduler.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org>
+ *
+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
+ * file.
+ *
+ * BFQ is a proportional-share storage-I/O scheduling algorithm based
+ * on the slice-by-slice service scheme of CFQ. But BFQ assigns
+ * budgets, measured in number of sectors, to processes instead of
+ * time slices. The device is not granted to the in-service process
+ * for a given time slice, but until it has exhausted its assigned
+ * budget. This change from the time to the service domain enables BFQ
+ * to distribute the device throughput among processes as desired,
+ * without any distortion due to throughput fluctuations, or to device
+ * internal queueing. BFQ uses an ad hoc internal scheduler, called
+ * B-WF2Q+, to schedule processes according to their budgets. More
+ * precisely, BFQ schedules queues associated with processes. Thanks to
+ * the accurate policy of B-WF2Q+, BFQ can afford to assign high
+ * budgets to I/O-bound processes issuing sequential requests (to
+ * boost the throughput), and yet guarantee a low latency to
+ * interactive and soft real-time applications.
+ *
+ * BFQ is described in [1], where also a reference to the initial, more
+ * theoretical paper on BFQ can be found. The interested reader can find
+ * in the latter paper full details on the main algorithm, as well as
+ * formulas of the guarantees and formal proofs of all the properties.
+ * With respect to the version of BFQ presented in these papers, this
+ * implementation adds a few more heuristics, such as the one that
+ * guarantees a low latency to soft real-time applications, and a
+ * hierarchical extension based on H-WF2Q+.
+ *
+ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with
+ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N)
+ * complexity derives from the one introduced with EEVDF in [3].
+ *
+ * [1] P. Valente and M. Andreolini, ``Improving Application Responsiveness
+ * with the BFQ Disk I/O Scheduler'',
+ * Proceedings of the 5th Annual International Systems and Storage
+ * Conference (SYSTOR '12), June 2012.
+ *
+ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf
+ *
+ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing
+ * Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689,
+ * Oct 1997.
+ *
+ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz
+ *
+ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline
+ * First: A Flexible and Accurate Mechanism for Proportional Share
+ * Resource Allocation,'' technical report.
+ *
+ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf
+ */
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/cgroup.h>
+#include <linux/elevator.h>
+#include <linux/jiffies.h>
+#include <linux/rbtree.h>
+#include <linux/ioprio.h>
+#include "bfq.h"
+#include "blk.h"
+
+/* Expiration time of sync (0) and async (1) requests, in ns. */
+static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
+
+/* Maximum backwards seek, in KiB. */
+static const int bfq_back_max = 16 * 1024;
+
+/* Penalty of a backwards seek, in number of sectors. */
+static const int bfq_back_penalty = 2;
+
+/* Idling period duration, in ns. */
+static u64 bfq_slice_idle = NSEC_PER_SEC / 125;
+
+/* Minimum number of assigned budgets for which stats are safe to compute. */
+static const int bfq_stats_min_budgets = 194;
+
+/* Default maximum budget values, in sectors and number of requests. */
+static const int bfq_default_max_budget = 16 * 1024;
+
+/*
+ * Async to sync throughput distribution is controlled as follows:
+ * when an async request is served, the entity is charged the number
+ * of sectors of the request, multiplied by the factor below
+ */
+static const int bfq_async_charge_factor = 10;
+
+/* Default timeout values, in jiffies, approximating CFQ defaults. */
+static const int bfq_timeout = HZ / 8;
+
+struct kmem_cache *bfq_pool;
+
+/* Below this threshold (in ms), we consider thinktime immediate. */
+#define BFQ_MIN_TT (2 * NSEC_PER_MSEC)
+
+/* hw_tag detection: parallel requests threshold and min samples needed. */
+#define BFQ_HW_QUEUE_THRESHOLD 4
+#define BFQ_HW_QUEUE_SAMPLES 32
+
+#define BFQQ_SEEK_THR (sector_t)(8 * 100)
+#define BFQQ_CLOSE_THR (sector_t)(8 * 1024)
+#define BFQQ_SEEKY(bfqq) (hweight32(bfqq->seek_history) > 32/8)
+
+/* Min samples used for peak rate estimation (for autotuning). */
+#define BFQ_PEAK_RATE_SAMPLES 32
+#define BFQ_RATE_SAMPLING_INT 300000ULL /* us */
+
+/* Shift used for peak rate fixed precision calculations. */
+#define BFQ_RATE_SHIFT 16
+
+/*
+ * By default, BFQ computes the duration of the weight raising for
+ * interactive applications automatically, using the following formula:
+ * duration = (R / r) * T, where r is the peak rate of the device, and
+ * R and T are two reference parameters.
+ * In particular, R is the peak rate of the reference device (see below),
+ * and T is a reference time: given the systems that are likely to be
+ * installed on the reference device according to its speed class, T is
+ * about the maximum time needed, under BFQ and while reading two files in
+ * parallel, to load typical large applications on these systems.
+ * In practice, the slower/faster the device at hand is, the more/less it
+ * takes to load applications with respect to the reference device.
+ * Accordingly, the longer/shorter BFQ grants weight raising to interactive
+ * applications.
+ *
+ * BFQ uses four different reference pairs (R, T), depending on:
+ * . whether the device is rotational or non-rotational;
+ * . whether the device is slow, such as old or portable HDDs, as well as
+ * SD cards, or fast, such as newer HDDs and SSDs.
+ *
+ * The device's speed class is dynamically (re)detected in
+ * bfq_update_peak_rate() every time the estimated peak rate is updated.
+ *
+ * In the following definitions, R_slow[0]/R_fast[0] and
+ * T_slow[0]/T_fast[0] are the reference values for a slow/fast
+ * rotational device, whereas R_slow[1]/R_fast[1] and
+ * T_slow[1]/T_fast[1] are the reference values for a slow/fast
+ * non-rotational device. Finally, device_speed_thresh are the
+ * thresholds used to switch between speed classes. The reference
+ * rates are not the actual peak rates of the devices used as a
+ * reference, but slightly lower values. The reason for using these
+ * slightly lower values is that the peak-rate estimator tends to
+ * yield slightly lower values than the actual peak rate (it can yield
+ * the actual peak rate only if there is only one process doing I/O,
+ * and the process does sequential I/O).
+ *
+ * Both the reference peak rates and the thresholds are measured in
+ * sectors/usec, left-shifted by BFQ_RATE_SHIFT.
+ */
+static int R_slow[2] = {1000, 10700};
+static int R_fast[2] = {14000, 33000};
+/*
+ * To improve readability, a conversion function is used to initialize the
+ * following arrays, which entails that they can be initialized only in a
+ * function.
+ */
+static int T_slow[2];
+static int T_fast[2];
+static int device_speed_thresh[2];
+
+#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \
+ { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
+
+#define RQ_BIC(rq) ((struct bfq_io_cq *) (rq)->elv.priv[0])
+#define RQ_BFQQ(rq) ((rq)->elv.priv[1])
+
+static void bfq_schedule_dispatch(struct bfq_data *bfqd);
+
+#include "bfq-ioc.c"
+#include "bfq-sched.c"
+#include "bfq-cgroup.c"
+
+#define bfq_class_idle(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
+#define bfq_class_rt(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_RT)
+
+#define bfq_sample_valid(samples) ((samples) > 80)
+
+/*
+ * We regard a request as SYNC, if either it's a read or has the SYNC bit
+ * set (in which case it could also be a direct WRITE).
+ */
+static int bfq_bio_sync(struct bio *bio)
+{
+ return bio_data_dir(bio) == READ || (bio->bi_opf & REQ_SYNC);
+}
+
+/*
+ * Scheduler run of queue, if there are requests pending and no one in the
+ * driver that will restart queueing.
+ */
+static void bfq_schedule_dispatch(struct bfq_data *bfqd)
+{
+ if (bfqd->queued != 0) {
+ bfq_log(bfqd, "schedule dispatch");
+ kblockd_schedule_work(&bfqd->unplug_work);
+ }
+}
+
+/*
+ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
+ * We choose the request that is closesr to the head right now. Distance
+ * behind the head is penalized and only allowed to a certain extent.
+ */
+static struct request *bfq_choose_req(struct bfq_data *bfqd,
+ struct request *rq1,
+ struct request *rq2,
+ sector_t last)
+{
+ sector_t s1, s2, d1 = 0, d2 = 0;
+ unsigned long back_max;
+#define BFQ_RQ1_WRAP 0x01 /* request 1 wraps */
+#define BFQ_RQ2_WRAP 0x02 /* request 2 wraps */
+ unsigned int wrap = 0; /* bit mask: requests behind the disk head? */
+
+ if (!rq1 || rq1 == rq2)
+ return rq2;
+ if (!rq2)
+ return rq1;
+
+ if (rq_is_sync(rq1) && !rq_is_sync(rq2))
+ return rq1;
+ else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
+ return rq2;
+ if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
+ return rq1;
+ else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META))
+ return rq2;
+
+ s1 = blk_rq_pos(rq1);
+ s2 = blk_rq_pos(rq2);
+
+ /*
+ * By definition, 1KiB is 2 sectors.
+ */
+ back_max = bfqd->bfq_back_max * 2;
+
+ /*
+ * Strict one way elevator _except_ in the case where we allow
+ * short backward seeks which are biased as twice the cost of a
+ * similar forward seek.
+ */
+ if (s1 >= last)
+ d1 = s1 - last;
+ else if (s1 + back_max >= last)
+ d1 = (last - s1) * bfqd->bfq_back_penalty;
+ else
+ wrap |= BFQ_RQ1_WRAP;
+
+ if (s2 >= last)
+ d2 = s2 - last;
+ else if (s2 + back_max >= last)
+ d2 = (last - s2) * bfqd->bfq_back_penalty;
+ else
+ wrap |= BFQ_RQ2_WRAP;
+
+ /* Found required data */
+
+ /*
+ * By doing switch() on the bit mask "wrap" we avoid having to
+ * check two variables for all permutations: --> faster!
+ */
+ switch (wrap) {
+ case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
+ if (d1 < d2)
+ return rq1;
+ else if (d2 < d1)
+ return rq2;
+
+ if (s1 >= s2)
+ return rq1;
+ else
+ return rq2;
+
+ case BFQ_RQ2_WRAP:
+ return rq1;
+ case BFQ_RQ1_WRAP:
+ return rq2;
+ case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */
+ default:
+ /*
+ * Since both rqs are wrapped,
+ * start with the one that's further behind head
+ * (--> only *one* back seek required),
+ * since back seek takes more time than forward.
+ */
+ if (s1 <= s2)
+ return rq1;
+ else
+ return rq2;
+ }
+}
+
+static struct bfq_queue *
+bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
+ sector_t sector, struct rb_node **ret_parent,
+ struct rb_node ***rb_link)
+{
+ struct rb_node **p, *parent;
+ struct bfq_queue *bfqq = NULL;
+
+ parent = NULL;
+ p = &root->rb_node;
+ while (*p) {
+ struct rb_node **n;
+
+ parent = *p;
+ bfqq = rb_entry(parent, struct bfq_queue, pos_node);
+
+ /*
+ * Sort strictly based on sector. Smallest to the left,
+ * largest to the right.
+ */
+ if (sector > blk_rq_pos(bfqq->next_rq))
+ n = &(*p)->rb_right;
+ else if (sector < blk_rq_pos(bfqq->next_rq))
+ n = &(*p)->rb_left;
+ else
+ break;
+ p = n;
+ bfqq = NULL;
+ }
+
+ *ret_parent = parent;
+ if (rb_link)
+ *rb_link = p;
+
+ bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d",
+ (unsigned long long) sector,
+ bfqq ? bfqq->pid : 0);
+
+ return bfqq;
+}
+
+static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct rb_node **p, *parent;
+ struct bfq_queue *__bfqq;
+
+ if (bfqq->pos_root) {
+ rb_erase(&bfqq->pos_node, bfqq->pos_root);
+ bfqq->pos_root = NULL;
+ }
+
+ if (bfq_class_idle(bfqq))
+ return;
+ if (!bfqq->next_rq)
+ return;
+
+ bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
+ __bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root,
+ blk_rq_pos(bfqq->next_rq), &parent, &p);
+ if (!__bfqq) {
+ rb_link_node(&bfqq->pos_node, parent, p);
+ rb_insert_color(&bfqq->pos_node, bfqq->pos_root);
+ } else
+ bfqq->pos_root = NULL;
+}
+
+/*
+ * Tell whether there are active queues or groups with differentiated weights.
+ */
+static bool bfq_differentiated_weights(struct bfq_data *bfqd)
+{
+ /*
+ * For weights to differ, at least one of the trees must contain
+ * at least two nodes.
+ */
+ return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
+ (bfqd->queue_weights_tree.rb_node->rb_left ||
+ bfqd->queue_weights_tree.rb_node->rb_right)
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ ) ||
+ (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) &&
+ (bfqd->group_weights_tree.rb_node->rb_left ||
+ bfqd->group_weights_tree.rb_node->rb_right)
+#endif
+ );
+}
+
+/*
+ * The following function returns true if every queue must receive the
+ * same share of the throughput (this condition is used when deciding
+ * whether idling may be disabled, see the comments in the function
+ * bfq_bfqq_may_idle()).
+ *
+ * Such a scenario occurs when:
+ * 1) all active queues have the same weight,
+ * 2) all active groups at the same level in the groups tree have the same
+ * weight,
+ * 3) all active groups at the same level in the groups tree have the same
+ * number of children.
+ *
+ * Unfortunately, keeping the necessary state for evaluating exactly the
+ * above symmetry conditions would be quite complex and time-consuming.
+ * Therefore this function evaluates, instead, the following stronger
+ * sub-conditions, for which it is much easier to maintain the needed
+ * state:
+ * 1) all active queues have the same weight,
+ * 2) all active groups have the same weight,
+ * 3) all active groups have at most one active child each.
+ * In particular, the last two conditions are always true if hierarchical
+ * support and the cgroups interface are not enabled, thus no state needs
+ * to be maintained in this case.
+ */
+static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
+{
+ return !bfq_differentiated_weights(bfqd);
+}
+
+/*
+ * If the weight-counter tree passed as input contains no counter for
+ * the weight of the input entity, then add that counter; otherwise just
+ * increment the existing counter.
+ *
+ * Note that weight-counter trees contain few nodes in mostly symmetric
+ * scenarios. For example, if all queues have the same weight, then the
+ * weight-counter tree for the queues may contain at most one node.
+ * This holds even if low_latency is on, because weight-raised queues
+ * are not inserted in the tree.
+ * In most scenarios, the rate at which nodes are created/destroyed
+ * should be low too.
+ */
+static void bfq_weights_tree_add(struct bfq_data *bfqd,
+ struct bfq_entity *entity,
+ struct rb_root *root)
+{
+ struct rb_node **new = &(root->rb_node), *parent = NULL;
+
+ /*
+ * Do not insert if the entity is already associated with a
+ * counter, which happens if:
+ * 1) the entity is associated with a queue,
+ * 2) a request arrival has caused the queue to become both
+ * non-weight-raised, and hence change its weight, and
+ * backlogged; in this respect, each of the two events
+ * causes an invocation of this function,
+ * 3) this is the invocation of this function caused by the
+ * second event. This second invocation is actually useless,
+ * and we handle this fact by exiting immediately. More
+ * efficient or clearer solutions might possibly be adopted.
+ */
+ if (entity->weight_counter)
+ return;
+
+ while (*new) {
+ struct bfq_weight_counter *__counter = container_of(*new,
+ struct bfq_weight_counter,
+ weights_node);
+ parent = *new;
+
+ if (entity->weight == __counter->weight) {
+ entity->weight_counter = __counter;
+ goto inc_counter;
+ }
+ if (entity->weight < __counter->weight)
+ new = &((*new)->rb_left);
+ else
+ new = &((*new)->rb_right);
+ }
+
+ entity->weight_counter = kzalloc(sizeof(struct bfq_weight_counter),
+ GFP_ATOMIC);
+ entity->weight_counter->weight = entity->weight;
+ rb_link_node(&entity->weight_counter->weights_node, parent, new);
+ rb_insert_color(&entity->weight_counter->weights_node, root);
+
+inc_counter:
+ entity->weight_counter->num_active++;
+}
+
+/*
+ * Decrement the weight counter associated with the entity, and, if the
+ * counter reaches 0, remove the counter from the tree.
+ * See the comments to the function bfq_weights_tree_add() for considerations
+ * about overhead.
+ */
+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
+ struct bfq_entity *entity,
+ struct rb_root *root)
+{
+ if (!entity->weight_counter)
+ return;
+
+ BUG_ON(RB_EMPTY_ROOT(root));
+ BUG_ON(entity->weight_counter->weight != entity->weight);
+
+ BUG_ON(!entity->weight_counter->num_active);
+ entity->weight_counter->num_active--;
+ if (entity->weight_counter->num_active > 0)
+ goto reset_entity_pointer;
+
+ rb_erase(&entity->weight_counter->weights_node, root);
+ kfree(entity->weight_counter);
+
+reset_entity_pointer:
+ entity->weight_counter = NULL;
+}
+
+static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct request *last)
+{
+ struct rb_node *rbnext = rb_next(&last->rb_node);
+ struct rb_node *rbprev = rb_prev(&last->rb_node);
+ struct request *next = NULL, *prev = NULL;
+
+ BUG_ON(RB_EMPTY_NODE(&last->rb_node));
+
+ if (rbprev)
+ prev = rb_entry_rq(rbprev);
+
+ if (rbnext)
+ next = rb_entry_rq(rbnext);
+ else {
+ rbnext = rb_first(&bfqq->sort_list);
+ if (rbnext && rbnext != &last->rb_node)
+ next = rb_entry_rq(rbnext);
+ }
+
+ return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last));
+}
+
+/* see the definition of bfq_async_charge_factor for details */
+static unsigned long bfq_serv_to_charge(struct request *rq,
+ struct bfq_queue *bfqq)
+{
+ if (bfq_bfqq_sync(bfqq) || bfqq->wr_coeff > 1)
+ return blk_rq_sectors(rq);
+
+ /*
+ * If there are no weight-raised queues, then amplify service
+ * by just the async charge factor; otherwise amplify service
+ * by twice the async charge factor, to further reduce latency
+ * for weight-raised queues.
+ */
+ if (bfqq->bfqd->wr_busy_queues == 0)
+ return blk_rq_sectors(rq) * bfq_async_charge_factor;
+
+ return blk_rq_sectors(rq) * 2 * bfq_async_charge_factor;
+}
+
+/**
+ * bfq_updated_next_req - update the queue after a new next_rq selection.
+ * @bfqd: the device data the queue belongs to.
+ * @bfqq: the queue to update.
+ *
+ * If the first request of a queue changes we make sure that the queue
+ * has enough budget to serve at least its first request (if the
+ * request has grown). We do this because if the queue has not enough
+ * budget for its first request, it has to go through two dispatch
+ * rounds to actually get it dispatched.
+ */
+static void bfq_updated_next_req(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+ struct request *next_rq = bfqq->next_rq;
+ unsigned long new_budget;
+
+ if (!next_rq)
+ return;
+
+ if (bfqq == bfqd->in_service_queue)
+ /*
+ * In order not to break guarantees, budgets cannot be
+ * changed after an entity has been selected.
+ */
+ return;
+
+ BUG_ON(entity->tree != &st->active);
+ BUG_ON(entity == entity->sched_data->in_service_entity);
+
+ new_budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+ if (entity->budget != new_budget) {
+ entity->budget = new_budget;
+ bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
+ new_budget);
+ bfq_activate_bfqq(bfqd, bfqq);
+ }
+}
+
+static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
+{
+ u64 dur;
+
+ if (bfqd->bfq_wr_max_time > 0)
+ return bfqd->bfq_wr_max_time;
+
+ dur = bfqd->RT_prod;
+ do_div(dur, bfqd->peak_rate);
+
+ /*
+ * Limit duration between 3 and 13 seconds. Tests show that
+ * higher values than 13 seconds often yield the opposite of
+ * the desired result, i.e., worsen responsiveness by letting
+ * non-interactive and non-soft-real-time applications
+ * preserve weight raising for a too long time interval.
+ *
+ * On the other end, lower values than 3 seconds make it
+ * difficult for most interactive tasks to complete their jobs
+ * before weight-raising finishes.
+ */
+ if (dur > msecs_to_jiffies(13000))
+ dur = msecs_to_jiffies(13000);
+ else if (dur < msecs_to_jiffies(3000))
+ dur = msecs_to_jiffies(3000);
+
+ return dur;
+}
+
+static void
+bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
+{
+ if (bic->saved_idle_window)
+ bfq_mark_bfqq_idle_window(bfqq);
+ else
+ bfq_clear_bfqq_idle_window(bfqq);
+
+ if (bic->saved_IO_bound)
+ bfq_mark_bfqq_IO_bound(bfqq);
+ else
+ bfq_clear_bfqq_IO_bound(bfqq);
+}
+
+static int bfqq_process_refs(struct bfq_queue *bfqq)
+{
+ int process_refs, io_refs;
+
+ lockdep_assert_held(bfqq->bfqd->queue->queue_lock);
+
+ io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE];
+ process_refs = bfqq->ref - io_refs - bfqq->entity.on_st;
+ BUG_ON(process_refs < 0);
+ return process_refs;
+}
+
+/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */
+static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct bfq_queue *item;
+ struct hlist_node *n;
+
+ hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node)
+ hlist_del_init(&item->burst_list_node);
+ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
+ bfqd->burst_size = 1;
+ bfqd->burst_parent_entity = bfqq->entity.parent;
+}
+
+/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */
+static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ /* Increment burst size to take into account also bfqq */
+ bfqd->burst_size++;
+
+ bfq_log_bfqq(bfqd, bfqq, "add_to_burst %d", bfqd->burst_size);
+
+ BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh);
+
+ if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) {
+ struct bfq_queue *pos, *bfqq_item;
+ struct hlist_node *n;
+
+ /*
+ * Enough queues have been activated shortly after each
+ * other to consider this burst as large.
+ */
+ bfqd->large_burst = true;
+ bfq_log_bfqq(bfqd, bfqq, "add_to_burst: large burst started");
+
+ /*
+ * We can now mark all queues in the burst list as
+ * belonging to a large burst.
+ */
+ hlist_for_each_entry(bfqq_item, &bfqd->burst_list,
+ burst_list_node) {
+ bfq_mark_bfqq_in_large_burst(bfqq_item);
+ bfq_log_bfqq(bfqd, bfqq_item, "marked in large burst");
+ }
+ bfq_mark_bfqq_in_large_burst(bfqq);
+ bfq_log_bfqq(bfqd, bfqq, "marked in large burst");
+
+ /*
+ * From now on, and until the current burst finishes, any
+ * new queue being activated shortly after the last queue
+ * was inserted in the burst can be immediately marked as
+ * belonging to a large burst. So the burst list is not
+ * needed any more. Remove it.
+ */
+ hlist_for_each_entry_safe(pos, n, &bfqd->burst_list,
+ burst_list_node)
+ hlist_del_init(&pos->burst_list_node);
+ } else /*
+ * Burst not yet large: add bfqq to the burst list. Do
+ * not increment the ref counter for bfqq, because bfqq
+ * is removed from the burst list before freeing bfqq
+ * in put_queue.
+ */
+ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
+}
+
+/*
+ * If many queues belonging to the same group happen to be created
+ * shortly after each other, then the processes associated with these
+ * queues have typically a common goal. In particular, bursts of queue
+ * creations are usually caused by services or applications that spawn
+ * many parallel threads/processes. Examples are systemd during boot,
+ * or git grep. To help these processes get their job done as soon as
+ * possible, it is usually better to not grant either weight-raising
+ * or device idling to their queues.
+ *
+ * In this comment we describe, firstly, the reasons why this fact
+ * holds, and, secondly, the next function, which implements the main
+ * steps needed to properly mark these queues so that they can then be
+ * treated in a different way.
+ *
+ * The above services or applications benefit mostly from a high
+ * throughput: the quicker the requests of the activated queues are
+ * cumulatively served, the sooner the target job of these queues gets
+ * completed. As a consequence, weight-raising any of these queues,
+ * which also implies idling the device for it, is almost always
+ * counterproductive. In most cases it just lowers throughput.
+ *
+ * On the other hand, a burst of queue creations may be caused also by
+ * the start of an application that does not consist of a lot of
+ * parallel I/O-bound threads. In fact, with a complex application,
+ * several short processes may need to be executed to start-up the
+ * application. In this respect, to start an application as quickly as
+ * possible, the best thing to do is in any case to privilege the I/O
+ * related to the application with respect to all other
+ * I/O. Therefore, the best strategy to start as quickly as possible
+ * an application that causes a burst of queue creations is to
+ * weight-raise all the queues created during the burst. This is the
+ * exact opposite of the best strategy for the other type of bursts.
+ *
+ * In the end, to take the best action for each of the two cases, the
+ * two types of bursts need to be distinguished. Fortunately, this
+ * seems relatively easy, by looking at the sizes of the bursts. In
+ * particular, we found a threshold such that only bursts with a
+ * larger size than that threshold are apparently caused by
+ * services or commands such as systemd or git grep. For brevity,
+ * hereafter we call just 'large' these bursts. BFQ *does not*
+ * weight-raise queues whose creation occurs in a large burst. In
+ * addition, for each of these queues BFQ performs or does not perform
+ * idling depending on which choice boosts the throughput more. The
+ * exact choice depends on the device and request pattern at
+ * hand.
+ *
+ * Unfortunately, false positives may occur while an interactive task
+ * is starting (e.g., an application is being started). The
+ * consequence is that the queues associated with the task do not
+ * enjoy weight raising as expected. Fortunately these false positives
+ * are very rare. They typically occur if some service happens to
+ * start doing I/O exactly when the interactive task starts.
+ *
+ * Turning back to the next function, it implements all the steps
+ * needed to detect the occurrence of a large burst and to properly
+ * mark all the queues belonging to it (so that they can then be
+ * treated in a different way). This goal is achieved by maintaining a
+ * "burst list" that holds, temporarily, the queues that belong to the
+ * burst in progress. The list is then used to mark these queues as
+ * belonging to a large burst if the burst does become large. The main
+ * steps are the following.
+ *
+ * . when the very first queue is created, the queue is inserted into the
+ * list (as it could be the first queue in a possible burst)
+ *
+ * . if the current burst has not yet become large, and a queue Q that does
+ * not yet belong to the burst is activated shortly after the last time
+ * at which a new queue entered the burst list, then the function appends
+ * Q to the burst list
+ *
+ * . if, as a consequence of the previous step, the burst size reaches
+ * the large-burst threshold, then
+ *
+ * . all the queues in the burst list are marked as belonging to a
+ * large burst
+ *
+ * . the burst list is deleted; in fact, the burst list already served
+ * its purpose (keeping temporarily track of the queues in a burst,
+ * so as to be able to mark them as belonging to a large burst in the
+ * previous sub-step), and now is not needed any more
+ *
+ * . the device enters a large-burst mode
+ *
+ * . if a queue Q that does not belong to the burst is created while
+ * the device is in large-burst mode and shortly after the last time
+ * at which a queue either entered the burst list or was marked as
+ * belonging to the current large burst, then Q is immediately marked
+ * as belonging to a large burst.
+ *
+ * . if a queue Q that does not belong to the burst is created a while
+ * later, i.e., not shortly after, than the last time at which a queue
+ * either entered the burst list or was marked as belonging to the
+ * current large burst, then the current burst is deemed as finished and:
+ *
+ * . the large-burst mode is reset if set
+ *
+ * . the burst list is emptied
+ *
+ * . Q is inserted in the burst list, as Q may be the first queue
+ * in a possible new burst (then the burst list contains just Q
+ * after this step).
+ */
+static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ /*
+ * If bfqq is already in the burst list or is part of a large
+ * burst, or finally has just been split, then there is
+ * nothing else to do.
+ */
+ if (!hlist_unhashed(&bfqq->burst_list_node) ||
+ bfq_bfqq_in_large_burst(bfqq) ||
+ time_is_after_eq_jiffies(bfqq->split_time +
+ msecs_to_jiffies(10)))
+ return;
+
+ /*
+ * If bfqq's creation happens late enough, or bfqq belongs to
+ * a different group than the burst group, then the current
+ * burst is finished, and related data structures must be
+ * reset.
+ *
+ * In this respect, consider the special case where bfqq is
+ * the very first queue created after BFQ is selected for this
+ * device. In this case, last_ins_in_burst and
+ * burst_parent_entity are not yet significant when we get
+ * here. But it is easy to verify that, whether or not the
+ * following condition is true, bfqq will end up being
+ * inserted into the burst list. In particular the list will
+ * happen to contain only bfqq. And this is exactly what has
+ * to happen, as bfqq may be the first queue of the first
+ * burst.
+ */
+ if (time_is_before_jiffies(bfqd->last_ins_in_burst +
+ bfqd->bfq_burst_interval) ||
+ bfqq->entity.parent != bfqd->burst_parent_entity) {
+ bfqd->large_burst = false;
+ bfq_reset_burst_list(bfqd, bfqq);
+ bfq_log_bfqq(bfqd, bfqq,
+ "handle_burst: late activation or different group");
+ goto end;
+ }
+
+ /*
+ * If we get here, then bfqq is being activated shortly after the
+ * last queue. So, if the current burst is also large, we can mark
+ * bfqq as belonging to this large burst immediately.
+ */
+ if (bfqd->large_burst) {
+ bfq_log_bfqq(bfqd, bfqq, "handle_burst: marked in burst");
+ bfq_mark_bfqq_in_large_burst(bfqq);
+ goto end;
+ }
+
+ /*
+ * If we get here, then a large-burst state has not yet been
+ * reached, but bfqq is being activated shortly after the last
+ * queue. Then we add bfqq to the burst.
+ */
+ bfq_add_to_burst(bfqd, bfqq);
+end:
+ /*
+ * At this point, bfqq either has been added to the current
+ * burst or has caused the current burst to terminate and a
+ * possible new burst to start. In particular, in the second
+ * case, bfqq has become the first queue in the possible new
+ * burst. In both cases last_ins_in_burst needs to be moved
+ * forward.
+ */
+ bfqd->last_ins_in_burst = jiffies;
+
+}
+
+static int bfq_bfqq_budget_left(struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ return entity->budget - entity->service;
+}
+
+/*
+ * If enough samples have been computed, return the current max budget
+ * stored in bfqd, which is dynamically updated according to the
+ * estimated disk peak rate; otherwise return the default max budget
+ */
+static int bfq_max_budget(struct bfq_data *bfqd)
+{
+ if (bfqd->budgets_assigned < bfq_stats_min_budgets)
+ return bfq_default_max_budget;
+ else
+ return bfqd->bfq_max_budget;
+}
+
+/*
+ * Return min budget, which is a fraction of the current or default
+ * max budget (trying with 1/32)
+ */
+static int bfq_min_budget(struct bfq_data *bfqd)
+{
+ if (bfqd->budgets_assigned < bfq_stats_min_budgets)
+ return bfq_default_max_budget / 32;
+ else
+ return bfqd->bfq_max_budget / 32;
+}
+
+static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ bool compensate,
+ enum bfqq_expiration reason);
+
+/*
+ * The next function, invoked after the input queue bfqq switches from
+ * idle to busy, updates the budget of bfqq. The function also tells
+ * whether the in-service queue should be expired, by returning
+ * true. The purpose of expiring the in-service queue is to give bfqq
+ * the chance to possibly preempt the in-service queue, and the reason
+ * for preempting the in-service queue is to achieve one of the two
+ * goals below.
+ *
+ * 1. Guarantee to bfqq its reserved bandwidth even if bfqq has
+ * expired because it has remained idle. In particular, bfqq may have
+ * expired for one of the following two reasons:
+ *
+ * - BFQ_BFQQ_NO_MORE_REQUEST bfqq did not enjoy any device idling and
+ * did not make it to issue a new request before its last request
+ * was served;
+ *
+ * - BFQ_BFQQ_TOO_IDLE bfqq did enjoy device idling, but did not issue
+ * a new request before the expiration of the idling-time.
+ *
+ * Even if bfqq has expired for one of the above reasons, the process
+ * associated with the queue may be however issuing requests greedily,
+ * and thus be sensitive to the bandwidth it receives (bfqq may have
+ * remained idle for other reasons: CPU high load, bfqq not enjoying
+ * idling, I/O throttling somewhere in the path from the process to
+ * the I/O scheduler, ...). But if, after every expiration for one of
+ * the above two reasons, bfqq has to wait for the service of at least
+ * one full budget of another queue before being served again, then
+ * bfqq is likely to get a much lower bandwidth or resource time than
+ * its reserved ones. To address this issue, two countermeasures need
+ * to be taken.
+ *
+ * First, the budget and the timestamps of bfqq need to be updated in
+ * a special way on bfqq reactivation: they need to be updated as if
+ * bfqq did not remain idle and did not expire. In fact, if they are
+ * computed as if bfqq expired and remained idle until reactivation,
+ * then the process associated with bfqq is treated as if, instead of
+ * being greedy, it stopped issuing requests when bfqq remained idle,
+ * and restarts issuing requests only on this reactivation. In other
+ * words, the scheduler does not help the process recover the "service
+ * hole" between bfqq expiration and reactivation. As a consequence,
+ * the process receives a lower bandwidth than its reserved one. In
+ * contrast, to recover this hole, the budget must be updated as if
+ * bfqq was not expired at all before this reactivation, i.e., it must
+ * be set to the value of the remaining budget when bfqq was
+ * expired. Along the same line, timestamps need to be assigned the
+ * value they had the last time bfqq was selected for service, i.e.,
+ * before last expiration. Thus timestamps need to be back-shifted
+ * with respect to their normal computation (see [1] for more details
+ * on this tricky aspect).
+ *
+ * Secondly, to allow the process to recover the hole, the in-service
+ * queue must be expired too, to give bfqq the chance to preempt it
+ * immediately. In fact, if bfqq has to wait for a full budget of the
+ * in-service queue to be completed, then it may become impossible to
+ * let the process recover the hole, even if the back-shifted
+ * timestamps of bfqq are lower than those of the in-service queue. If
+ * this happens for most or all of the holes, then the process may not
+ * receive its reserved bandwidth. In this respect, it is worth noting
+ * that, being the service of outstanding requests unpreemptible, a
+ * little fraction of the holes may however be unrecoverable, thereby
+ * causing a little loss of bandwidth.
+ *
+ * The last important point is detecting whether bfqq does need this
+ * bandwidth recovery. In this respect, the next function deems the
+ * process associated with bfqq greedy, and thus allows it to recover
+ * the hole, if: 1) the process is waiting for the arrival of a new
+ * request (which implies that bfqq expired for one of the above two
+ * reasons), and 2) such a request has arrived soon. The first
+ * condition is controlled through the flag non_blocking_wait_rq,
+ * while the second through the flag arrived_in_time. If both
+ * conditions hold, then the function computes the budget in the
+ * above-described special way, and signals that the in-service queue
+ * should be expired. Timestamp back-shifting is done later in
+ * __bfq_activate_entity.
+ *
+ * 2. Reduce latency. Even if timestamps are not backshifted to let
+ * the process associated with bfqq recover a service hole, bfqq may
+ * however happen to have, after being (re)activated, a lower finish
+ * timestamp than the in-service queue. That is, the next budget of
+ * bfqq may have to be completed before the one of the in-service
+ * queue. If this is the case, then preempting the in-service queue
+ * allows this goal to be achieved, apart from the unpreemptible,
+ * outstanding requests mentioned above.
+ *
+ * Unfortunately, regardless of which of the above two goals one wants
+ * to achieve, service trees need first to be updated to know whether
+ * the in-service queue must be preempted. To have service trees
+ * correctly updated, the in-service queue must be expired and
+ * rescheduled, and bfqq must be scheduled too. This is one of the
+ * most costly operations (in future versions, the scheduling
+ * mechanism may be re-designed in such a way to make it possible to
+ * know whether preemption is needed without needing to update service
+ * trees). In addition, queue preemptions almost always cause random
+ * I/O, and thus loss of throughput. Because of these facts, the next
+ * function adopts the following simple scheme to avoid both costly
+ * operations and too frequent preemptions: it requests the expiration
+ * of the in-service queue (unconditionally) only for queues that need
+ * to recover a hole, or that either are weight-raised or deserve to
+ * be weight-raised.
+ */
+static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ bool arrived_in_time,
+ bool wr_or_deserves_wr)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time) {
+ /*
+ * We do not clear the flag non_blocking_wait_rq here, as
+ * the latter is used in bfq_activate_bfqq to signal
+ * that timestamps need to be back-shifted (and is
+ * cleared right after).
+ */
+
+ /*
+ * In next assignment we rely on that either
+ * entity->service or entity->budget are not updated
+ * on expiration if bfqq is empty (see
+ * __bfq_bfqq_recalc_budget). Thus both quantities
+ * remain unchanged after such an expiration, and the
+ * following statement therefore assigns to
+ * entity->budget the remaining budget on such an
+ * expiration. For clarity, entity->service is not
+ * updated on expiration in any case, and, in normal
+ * operation, is reset only when bfqq is selected for
+ * service (see bfq_get_next_queue).
+ */
+ BUG_ON(bfqq->max_budget < 0);
+ entity->budget = min_t(unsigned long,
+ bfq_bfqq_budget_left(bfqq),
+ bfqq->max_budget);
+
+ BUG_ON(entity->budget < 0);
+ return true;
+ }
+
+ BUG_ON(bfqq->max_budget < 0);
+ entity->budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(bfqq->next_rq, bfqq));
+ BUG_ON(entity->budget < 0);
+
+ bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
+ return wr_or_deserves_wr;
+}
+
+static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ unsigned int old_wr_coeff,
+ bool wr_or_deserves_wr,
+ bool interactive,
+ bool in_burst,
+ bool soft_rt)
+{
+ if (old_wr_coeff == 1 && wr_or_deserves_wr) {
+ /* start a weight-raising period */
+ if (interactive) {
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff;
+ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+ } else {
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff *
+ BFQ_SOFTRT_WEIGHT_FACTOR;
+ bfqq->wr_cur_max_time =
+ bfqd->bfq_wr_rt_max_time;
+ }
+ /*
+ * If needed, further reduce budget to make sure it is
+ * close to bfqq's backlog, so as to reduce the
+ * scheduling-error component due to a too large
+ * budget. Do not care about throughput consequences,
+ * but only about latency. Finally, do not assign a
+ * too small budget either, to avoid increasing
+ * latency by causing too frequent expirations.
+ */
+ bfqq->entity.budget = min_t(unsigned long,
+ bfqq->entity.budget,
+ 2 * bfq_min_budget(bfqd));
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "wrais starting at %lu, rais_max_time %u",
+ jiffies,
+ jiffies_to_msecs(bfqq->wr_cur_max_time));
+ } else if (old_wr_coeff > 1) {
+ if (interactive) { /* update wr coeff and duration */
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff;
+ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+ } else if (in_burst) {
+ bfqq->wr_coeff = 1;
+ bfq_log_bfqq(bfqd, bfqq,
+ "wrais ending at %lu, rais_max_time %u",
+ jiffies,
+ jiffies_to_msecs(bfqq->
+ wr_cur_max_time));
+ } else if (soft_rt) {
+ /*
+ * The application is now or still meeting the
+ * requirements for being deemed soft rt. We
+ * can then correctly and safely (re)charge
+ * the weight-raising duration for the
+ * application with the weight-raising
+ * duration for soft rt applications.
+ *
+ * In particular, doing this recharge now, i.e.,
+ * before the weight-raising period for the
+ * application finishes, reduces the probability
+ * of the following negative scenario:
+ * 1) the weight of a soft rt application is
+ * raised at startup (as for any newly
+ * created application),
+ * 2) since the application is not interactive,
+ * at a certain time weight-raising is
+ * stopped for the application,
+ * 3) at that time the application happens to
+ * still have pending requests, and hence
+ * is destined to not have a chance to be
+ * deemed soft rt before these requests are
+ * completed (see the comments to the
+ * function bfq_bfqq_softrt_next_start()
+ * for details on soft rt detection),
+ * 4) these pending requests experience a high
+ * latency because the application is not
+ * weight-raised while they are pending.
+ */
+ bfqq->last_wr_start_finish = jiffies;
+ bfqq->wr_cur_max_time =
+ bfqd->bfq_wr_rt_max_time;
+ if (bfqq->wr_coeff < bfqd->bfq_wr_coeff *
+ BFQ_SOFTRT_WEIGHT_FACTOR) {
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff *
+ BFQ_SOFTRT_WEIGHT_FACTOR;
+ bfq_log_bfqq(bfqd, bfqq,
+ "moving forward soft_rt wr duration");
+
+ } else
+ bfq_log_bfqq(bfqd, bfqq,
+ "switching to soft_rt wr");
+ }
+ }
+}
+
+static bool bfq_bfqq_idle_for_long_time(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ return bfqq->dispatched == 0 &&
+ time_is_before_jiffies(
+ bfqq->budget_timeout +
+ bfqd->bfq_wr_min_idle_time);
+}
+
+static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ int old_wr_coeff,
+ struct request *rq,
+ bool *interactive)
+{
+ bool soft_rt, in_burst, wr_or_deserves_wr,
+ bfqq_wants_to_preempt,
+ idle_for_long_time = bfq_bfqq_idle_for_long_time(bfqd, bfqq),
+ /*
+ * See the comments on
+ * bfq_bfqq_update_budg_for_activation for
+ * details on the usage of the next variable.
+ */
+ arrived_in_time = ktime_get_ns() <=
+ RQ_BIC(rq)->ttime.last_end_request +
+ bfqd->bfq_slice_idle * 3;
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "bfq_add_request non-busy: "
+ "jiffies %lu, in_time %d, idle_long %d busyw %d "
+ "wr_coeff %u",
+ jiffies, arrived_in_time,
+ idle_for_long_time,
+ bfq_bfqq_non_blocking_wait_rq(bfqq),
+ old_wr_coeff);
+
+ BUG_ON(bfqq->entity.budget < bfqq->entity.service);
+
+ BUG_ON(bfqq == bfqd->in_service_queue);
+ bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq,
+ req_op(rq), rq->cmd_flags);
+
+ /*
+ * bfqq deserves to be weight-raised if:
+ * - it is sync,
+ * - it does not belong to a large burst,
+ * - it has been idle for enough time or is soft real-time,
+ * - is linked to a bfq_io_cq (it is not shared in any sense)
+ */
+ in_burst = bfq_bfqq_in_large_burst(bfqq);
+ soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
+ !in_burst &&
+ time_is_before_jiffies(bfqq->soft_rt_next_start);
+ *interactive =
+ !in_burst &&
+ idle_for_long_time;
+ wr_or_deserves_wr = bfqd->low_latency &&
+ (bfqq->wr_coeff > 1 ||
+ (bfq_bfqq_sync(bfqq) &&
+ bfqq->bic && (*interactive || soft_rt)));
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "bfq_add_request: "
+ "in_burst %d, "
+ "soft_rt %d (next %lu), inter %d, bic %p",
+ bfq_bfqq_in_large_burst(bfqq), soft_rt,
+ bfqq->soft_rt_next_start,
+ *interactive,
+ bfqq->bic);
+
+ /*
+ * Using the last flag, update budget and check whether bfqq
+ * may want to preempt the in-service queue.
+ */
+ bfqq_wants_to_preempt =
+ bfq_bfqq_update_budg_for_activation(bfqd, bfqq,
+ arrived_in_time,
+ wr_or_deserves_wr);
+
+ /*
+ * If bfqq happened to be activated in a burst, but has been
+ * idle for much more than an interactive queue, then we
+ * assume that, in the overall I/O initiated in the burst, the
+ * I/O associated with bfqq is finished. So bfqq does not need
+ * to be treated as a queue belonging to a burst
+ * anymore. Accordingly, we reset bfqq's in_large_burst flag
+ * if set, and remove bfqq from the burst list if it's
+ * there. We do not decrement burst_size, because the fact
+ * that bfqq does not need to belong to the burst list any
+ * more does not invalidate the fact that bfqq was created in
+ * a burst.
+ */
+ if (likely(!bfq_bfqq_just_created(bfqq)) &&
+ idle_for_long_time &&
+ time_is_before_jiffies(
+ bfqq->budget_timeout +
+ msecs_to_jiffies(10000))) {
+ hlist_del_init(&bfqq->burst_list_node);
+ bfq_clear_bfqq_in_large_burst(bfqq);
+ }
+
+ bfq_clear_bfqq_just_created(bfqq);
+
+ if (!bfq_bfqq_IO_bound(bfqq)) {
+ if (arrived_in_time) {
+ bfqq->requests_within_timer++;
+ if (bfqq->requests_within_timer >=
+ bfqd->bfq_requests_within_timer)
+ bfq_mark_bfqq_IO_bound(bfqq);
+ } else
+ bfqq->requests_within_timer = 0;
+ bfq_log_bfqq(bfqd, bfqq, "requests in time %d",
+ bfqq->requests_within_timer);
+ }
+
+ if (bfqd->low_latency) {
+ if (unlikely(time_is_after_jiffies(bfqq->split_time)))
+ /* wraparound */
+ bfqq->split_time =
+ jiffies - bfqd->bfq_wr_min_idle_time - 1;
+
+ if (time_is_before_jiffies(bfqq->split_time +
+ bfqd->bfq_wr_min_idle_time)) {
+ bfq_update_bfqq_wr_on_rq_arrival(bfqd, bfqq,
+ old_wr_coeff,
+ wr_or_deserves_wr,
+ *interactive,
+ in_burst,
+ soft_rt);
+
+ if (old_wr_coeff != bfqq->wr_coeff)
+ bfqq->entity.prio_changed = 1;
+ }
+ }
+
+ bfqq->last_idle_bklogged = jiffies;
+ bfqq->service_from_backlogged = 0;
+ bfq_clear_bfqq_softrt_update(bfqq);
+
+ bfq_add_bfqq_busy(bfqd, bfqq);
+
+ /*
+ * Expire in-service queue only if preemption may be needed
+ * for guarantees. In this respect, the function
+ * next_queue_may_preempt just checks a simple, necessary
+ * condition, and not a sufficient condition based on
+ * timestamps. In fact, for the latter condition to be
+ * evaluated, timestamps would need first to be updated, and
+ * this operation is quite costly (see the comments on the
+ * function bfq_bfqq_update_budg_for_activation).
+ */
+ if (bfqd->in_service_queue && bfqq_wants_to_preempt &&
+ bfqd->in_service_queue->wr_coeff < bfqq->wr_coeff &&
+ next_queue_may_preempt(bfqd)) {
+ struct bfq_queue *in_serv =
+ bfqd->in_service_queue;
+ BUG_ON(in_serv == bfqq);
+
+ bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
+ false, BFQ_BFQQ_PREEMPTED);
+ BUG_ON(in_serv->entity.budget < 0);
+ }
+}
+
+static void bfq_add_request(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ struct request *next_rq, *prev;
+ unsigned int old_wr_coeff = bfqq->wr_coeff;
+ bool interactive = false;
+
+ bfq_log_bfqq(bfqd, bfqq, "add_request: size %u %s",
+ blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A");
+
+ if (bfqq->wr_coeff > 1) /* queue is being weight-raised */
+ bfq_log_bfqq(bfqd, bfqq,
+ "raising period dur %u/%u msec, old coeff %u, w %d(%d)",
+ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
+ jiffies_to_msecs(bfqq->wr_cur_max_time),
+ bfqq->wr_coeff,
+ bfqq->entity.weight, bfqq->entity.orig_weight);
+
+ bfqq->queued[rq_is_sync(rq)]++;
+ bfqd->queued++;
+
+ elv_rb_add(&bfqq->sort_list, rq);
+
+ /*
+ * Check if this request is a better next-to-serve candidate.
+ */
+ prev = bfqq->next_rq;
+ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
+ BUG_ON(!next_rq);
+ bfqq->next_rq = next_rq;
+
+ /*
+ * Adjust priority tree position, if next_rq changes.
+ */
+ if (prev != bfqq->next_rq)
+ bfq_pos_tree_add_move(bfqd, bfqq);
+
+ if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */
+ bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, old_wr_coeff,
+ rq, &interactive);
+ else {
+ if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) &&
+ time_is_before_jiffies(
+ bfqq->last_wr_start_finish +
+ bfqd->bfq_wr_min_inter_arr_async)) {
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff;
+ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+
+ bfqd->wr_busy_queues++;
+ bfqq->entity.prio_changed = 1;
+ bfq_log_bfqq(bfqd, bfqq,
+ "non-idle wrais starting, "
+ "wr_max_time %u wr_busy %d",
+ jiffies_to_msecs(bfqq->wr_cur_max_time),
+ bfqd->wr_busy_queues);
+ }
+ if (prev != bfqq->next_rq)
+ bfq_updated_next_req(bfqd, bfqq);
+ }
+
+ /*
+ * Assign jiffies to last_wr_start_finish in the following
+ * cases:
+ *
+ * . if bfqq is not going to be weight-raised, because, for
+ * non weight-raised queues, last_wr_start_finish stores the
+ * arrival time of the last request; as of now, this piece
+ * of information is used only for deciding whether to
+ * weight-raise async queues
+ *
+ * . if bfqq is not weight-raised, because, if bfqq is now
+ * switching to weight-raised, then last_wr_start_finish
+ * stores the time when weight-raising starts
+ *
+ * . if bfqq is interactive, because, regardless of whether
+ * bfqq is currently weight-raised, the weight-raising
+ * period must start or restart (this case is considered
+ * separately because it is not detected by the above
+ * conditions, if bfqq is already weight-raised)
+ *
+ * last_wr_start_finish has to be updated also if bfqq is soft
+ * real-time, because the weight-raising period is constantly
+ * restarted on idle-to-busy transitions for these queues, but
+ * this is already done in bfq_bfqq_handle_idle_busy_switch if
+ * needed.
+ */
+ if (bfqd->low_latency &&
+ (old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive))
+ bfqq->last_wr_start_finish = jiffies;
+}
+
+static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
+ struct bio *bio)
+{
+ struct task_struct *tsk = current;
+ struct bfq_io_cq *bic;
+ struct bfq_queue *bfqq;
+
+ bic = bfq_bic_lookup(bfqd, tsk->io_context);
+ if (!bic)
+ return NULL;
+
+ bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio));
+ if (bfqq)
+ return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio));
+
+ return NULL;
+}
+
+static sector_t get_sdist(sector_t last_pos, struct request *rq)
+{
+ sector_t sdist = 0;
+
+ if (last_pos) {
+ if (last_pos < blk_rq_pos(rq))
+ sdist = blk_rq_pos(rq) - last_pos;
+ else
+ sdist = last_pos - blk_rq_pos(rq);
+ }
+
+ return sdist;
+}
+
+static void bfq_activate_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ bfqd->rq_in_driver++;
+}
+
+static void bfq_deactivate_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+
+ BUG_ON(bfqd->rq_in_driver == 0);
+ bfqd->rq_in_driver--;
+}
+
+static void bfq_remove_request(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ const int sync = rq_is_sync(rq);
+
+ BUG_ON(bfqq->entity.service > bfqq->entity.budget &&
+ bfqq == bfqd->in_service_queue);
+
+ if (bfqq->next_rq == rq) {
+ bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
+ bfq_updated_next_req(bfqd, bfqq);
+ }
+
+ if (rq->queuelist.prev != &rq->queuelist)
+ list_del_init(&rq->queuelist);
+ BUG_ON(bfqq->queued[sync] == 0);
+ bfqq->queued[sync]--;
+ bfqd->queued--;
+ elv_rb_del(&bfqq->sort_list, rq);
+
+ if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ BUG_ON(bfqq->entity.budget < 0);
+
+ if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) {
+ bfq_del_bfqq_busy(bfqd, bfqq, 1);
+
+ /* bfqq emptied. In normal operation, when
+ * bfqq is empty, bfqq->entity.service and
+ * bfqq->entity.budget must contain,
+ * respectively, the service received and the
+ * budget used last time bfqq emptied. These
+ * facts do not hold in this case, as at least
+ * this last removal occurred while bfqq is
+ * not in service. To avoid inconsistencies,
+ * reset both bfqq->entity.service and
+ * bfqq->entity.budget.
+ */
+ bfqq->entity.budget = bfqq->entity.service = 0;
+ }
+
+ /*
+ * Remove queue from request-position tree as it is empty.
+ */
+ if (bfqq->pos_root) {
+ rb_erase(&bfqq->pos_node, bfqq->pos_root);
+ bfqq->pos_root = NULL;
+ }
+ }
+
+ if (rq->cmd_flags & REQ_META) {
+ BUG_ON(bfqq->meta_pending == 0);
+ bfqq->meta_pending--;
+ }
+ bfqg_stats_update_io_remove(bfqq_group(bfqq), req_op(rq),
+ rq->cmd_flags);
+}
+
+static int bfq_merge(struct request_queue *q, struct request **req,
+ struct bio *bio)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct request *__rq;
+
+ __rq = bfq_find_rq_fmerge(bfqd, bio);
+ if (__rq && elv_bio_merge_ok(__rq, bio)) {
+ *req = __rq;
+ return ELEVATOR_FRONT_MERGE;
+ }
+
+ return ELEVATOR_NO_MERGE;
+}
+
+static void bfq_merged_request(struct request_queue *q, struct request *req,
+ int type)
+{
+ if (type == ELEVATOR_FRONT_MERGE &&
+ rb_prev(&req->rb_node) &&
+ blk_rq_pos(req) <
+ blk_rq_pos(container_of(rb_prev(&req->rb_node),
+ struct request, rb_node))) {
+ struct bfq_queue *bfqq = RQ_BFQQ(req);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ struct request *prev, *next_rq;
+
+ /* Reposition request in its sort_list */
+ elv_rb_del(&bfqq->sort_list, req);
+ elv_rb_add(&bfqq->sort_list, req);
+ /* Choose next request to be served for bfqq */
+ prev = bfqq->next_rq;
+ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
+ bfqd->last_position);
+ BUG_ON(!next_rq);
+ bfqq->next_rq = next_rq;
+ /*
+ * If next_rq changes, update both the queue's budget to
+ * fit the new request and the queue's position in its
+ * rq_pos_tree.
+ */
+ if (prev != bfqq->next_rq) {
+ bfq_updated_next_req(bfqd, bfqq);
+ bfq_pos_tree_add_move(bfqd, bfqq);
+ }
+ }
+}
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+static void bfq_bio_merged(struct request_queue *q, struct request *req,
+ struct bio *bio)
+{
+ bfqg_stats_update_io_merged(bfqq_group(RQ_BFQQ(req)), bio_op(bio),
+ bio->bi_opf);
+}
+#endif
+
+static void bfq_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next);
+
+ /*
+ * If next and rq belong to the same bfq_queue and next is older
+ * than rq, then reposition rq in the fifo (by substituting next
+ * with rq). Otherwise, if next and rq belong to different
+ * bfq_queues, never reposition rq: in fact, we would have to
+ * reposition it with respect to next's position in its own fifo,
+ * which would most certainly be too expensive with respect to
+ * the benefits.
+ */
+ if (bfqq == next_bfqq &&
+ !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
+ next->fifo_time < rq->fifo_time) {
+ list_del_init(&rq->queuelist);
+ list_replace_init(&next->queuelist, &rq->queuelist);
+ rq->fifo_time = next->fifo_time;
+ }
+
+ if (bfqq->next_rq == next)
+ bfqq->next_rq = rq;
+
+ bfq_remove_request(next);
+ bfqg_stats_update_io_merged(bfqq_group(bfqq), req_op(next),
+ next->cmd_flags);
+}
+
+/* Must be called with bfqq != NULL */
+static void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
+{
+ BUG_ON(!bfqq);
+
+ if (bfq_bfqq_busy(bfqq))
+ bfqq->bfqd->wr_busy_queues--;
+ bfqq->wr_coeff = 1;
+ bfqq->wr_cur_max_time = 0;
+ /*
+ * Trigger a weight change on the next invocation of
+ * __bfq_entity_update_weight_prio.
+ */
+ bfqq->entity.prio_changed = 1;
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "end_wr: wr_busy %d",
+ bfqq->bfqd->wr_busy_queues);
+}
+
+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
+ struct bfq_group *bfqg)
+{
+ int i, j;
+
+ for (i = 0; i < 2; i++)
+ for (j = 0; j < IOPRIO_BE_NR; j++)
+ if (bfqg->async_bfqq[i][j])
+ bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]);
+ if (bfqg->async_idle_bfqq)
+ bfq_bfqq_end_wr(bfqg->async_idle_bfqq);
+}
+
+static void bfq_end_wr(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq;
+
+ spin_lock_irq(bfqd->queue->queue_lock);
+
+ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
+ bfq_bfqq_end_wr(bfqq);
+ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list)
+ bfq_bfqq_end_wr(bfqq);
+ bfq_end_wr_async(bfqd);
+
+ spin_unlock_irq(bfqd->queue->queue_lock);
+}
+
+static sector_t bfq_io_struct_pos(void *io_struct, bool request)
+{
+ if (request)
+ return blk_rq_pos(io_struct);
+ else
+ return ((struct bio *)io_struct)->bi_iter.bi_sector;
+}
+
+static int bfq_rq_close_to_sector(void *io_struct, bool request,
+ sector_t sector)
+{
+ return abs(bfq_io_struct_pos(io_struct, request) - sector) <=
+ BFQQ_CLOSE_THR;
+}
+
+static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ sector_t sector)
+{
+ struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
+ struct rb_node *parent, *node;
+ struct bfq_queue *__bfqq;
+
+ if (RB_EMPTY_ROOT(root))
+ return NULL;
+
+ /*
+ * First, if we find a request starting at the end of the last
+ * request, choose it.
+ */
+ __bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL);
+ if (__bfqq)
+ return __bfqq;
+
+ /*
+ * If the exact sector wasn't found, the parent of the NULL leaf
+ * will contain the closest sector (rq_pos_tree sorted by
+ * next_request position).
+ */
+ __bfqq = rb_entry(parent, struct bfq_queue, pos_node);
+ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
+ return __bfqq;
+
+ if (blk_rq_pos(__bfqq->next_rq) < sector)
+ node = rb_next(&__bfqq->pos_node);
+ else
+ node = rb_prev(&__bfqq->pos_node);
+ if (!node)
+ return NULL;
+
+ __bfqq = rb_entry(node, struct bfq_queue, pos_node);
+ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
+ return __bfqq;
+
+ return NULL;
+}
+
+static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd,
+ struct bfq_queue *cur_bfqq,
+ sector_t sector)
+{
+ struct bfq_queue *bfqq;
+
+ /*
+ * We shall notice if some of the queues are cooperating,
+ * e.g., working closely on the same area of the device. In
+ * that case, we can group them together and: 1) don't waste
+ * time idling, and 2) serve the union of their requests in
+ * the best possible order for throughput.
+ */
+ bfqq = bfqq_find_close(bfqd, cur_bfqq, sector);
+ if (!bfqq || bfqq == cur_bfqq)
+ return NULL;
+
+ return bfqq;
+}
+
+static struct bfq_queue *
+bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
+{
+ int process_refs, new_process_refs;
+ struct bfq_queue *__bfqq;
+
+ /*
+ * If there are no process references on the new_bfqq, then it is
+ * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain
+ * may have dropped their last reference (not just their last process
+ * reference).
+ */
+ if (!bfqq_process_refs(new_bfqq))
+ return NULL;
+
+ /* Avoid a circular list and skip interim queue merges. */
+ while ((__bfqq = new_bfqq->new_bfqq)) {
+ if (__bfqq == bfqq)
+ return NULL;
+ new_bfqq = __bfqq;
+ }
+
+ process_refs = bfqq_process_refs(bfqq);
+ new_process_refs = bfqq_process_refs(new_bfqq);
+ /*
+ * If the process for the bfqq has gone away, there is no
+ * sense in merging the queues.
+ */
+ if (process_refs == 0 || new_process_refs == 0)
+ return NULL;
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d",
+ new_bfqq->pid);
+
+ /*
+ * Merging is just a redirection: the requests of the process
+ * owning one of the two queues are redirected to the other queue.
+ * The latter queue, in its turn, is set as shared if this is the
+ * first time that the requests of some process are redirected to
+ * it.
+ *
+ * We redirect bfqq to new_bfqq and not the opposite, because we
+ * are in the context of the process owning bfqq, hence we have
+ * the io_cq of this process. So we can immediately configure this
+ * io_cq to redirect the requests of the process to new_bfqq.
+ *
+ * NOTE, even if new_bfqq coincides with the in-service queue, the
+ * io_cq of new_bfqq is not available, because, if the in-service
+ * queue is shared, bfqd->in_service_bic may not point to the
+ * io_cq of the in-service queue.
+ * Redirecting the requests of the process owning bfqq to the
+ * currently in-service queue is in any case the best option, as
+ * we feed the in-service queue with new requests close to the
+ * last request served and, by doing so, hopefully increase the
+ * throughput.
+ */
+ bfqq->new_bfqq = new_bfqq;
+ new_bfqq->ref += process_refs;
+ return new_bfqq;
+}
+
+static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
+ struct bfq_queue *new_bfqq)
+{
+ if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) ||
+ (bfqq->ioprio_class != new_bfqq->ioprio_class))
+ return false;
+
+ /*
+ * If either of the queues has already been detected as seeky,
+ * then merging it with the other queue is unlikely to lead to
+ * sequential I/O.
+ */
+ if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq))
+ return false;
+
+ /*
+ * Interleaved I/O is known to be done by (some) applications
+ * only for reads, so it does not make sense to merge async
+ * queues.
+ */
+ if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq))
+ return false;
+
+ return true;
+}
+
+/*
+ * If this function returns true, then bfqq cannot be merged. The idea
+ * is that true cooperation happens very early after processes start
+ * to do I/O. Usually, late cooperations are just accidental false
+ * positives. In case bfqq is weight-raised, such false positives
+ * would evidently degrade latency guarantees for bfqq.
+ */
+bool wr_from_too_long(struct bfq_queue *bfqq)
+{
+ return bfqq->wr_coeff > 1 &&
+ time_is_before_jiffies(bfqq->last_wr_start_finish +
+ msecs_to_jiffies(100));
+}
+
+/*
+ * Attempt to schedule a merge of bfqq with the currently in-service
+ * queue or with a close queue among the scheduled queues. Return
+ * NULL if no merge was scheduled, a pointer to the shared bfq_queue
+ * structure otherwise.
+ *
+ * The OOM queue is not allowed to participate to cooperation: in fact, since
+ * the requests temporarily redirected to the OOM queue could be redirected
+ * again to dedicated queues at any time, the state needed to correctly
+ * handle merging with the OOM queue would be quite complex and expensive
+ * to maintain. Besides, in such a critical condition as an out of memory,
+ * the benefits of queue merging may be little relevant, or even negligible.
+ *
+ * Weight-raised queues can be merged only if their weight-raising
+ * period has just started. In fact cooperating processes are usually
+ * started together. Thus, with this filter we avoid false positives
+ * that would jeopardize low-latency guarantees.
+ *
+ * WARNING: queue merging may impair fairness among non-weight raised
+ * queues, for at least two reasons: 1) the original weight of a
+ * merged queue may change during the merged state, 2) even being the
+ * weight the same, a merged queue may be bloated with many more
+ * requests than the ones produced by its originally-associated
+ * process.
+ */
+static struct bfq_queue *
+bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ void *io_struct, bool request)
+{
+ struct bfq_queue *in_service_bfqq, *new_bfqq;
+
+ if (bfqq->new_bfqq)
+ return bfqq->new_bfqq;
+
+ if (io_struct && wr_from_too_long(bfqq) &&
+ likely(bfqq != &bfqd->oom_bfqq))
+ bfq_log_bfqq(bfqd, bfqq,
+ "would have looked for coop, but bfq%d wr",
+ bfqq->pid);
+
+ if (!io_struct ||
+ wr_from_too_long(bfqq) ||
+ unlikely(bfqq == &bfqd->oom_bfqq))
+ return NULL;
+
+ /* If there is only one backlogged queue, don't search. */
+ if (bfqd->busy_queues == 1)
+ return NULL;
+
+ in_service_bfqq = bfqd->in_service_queue;
+
+ if (in_service_bfqq && in_service_bfqq != bfqq &&
+ bfqd->in_service_bic && wr_from_too_long(in_service_bfqq)
+ && likely(in_service_bfqq == &bfqd->oom_bfqq))
+ bfq_log_bfqq(bfqd, bfqq,
+ "would have tried merge with in-service-queue, but wr");
+
+ if (!in_service_bfqq || in_service_bfqq == bfqq ||
+ !bfqd->in_service_bic || wr_from_too_long(in_service_bfqq) ||
+ unlikely(in_service_bfqq == &bfqd->oom_bfqq))
+ goto check_scheduled;
+
+ if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) &&
+ bfqq->entity.parent == in_service_bfqq->entity.parent &&
+ bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) {
+ new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq);
+ if (new_bfqq)
+ return new_bfqq;
+ }
+ /*
+ * Check whether there is a cooperator among currently scheduled
+ * queues. The only thing we need is that the bio/request is not
+ * NULL, as we need it to establish whether a cooperator exists.
+ */
+check_scheduled:
+ new_bfqq = bfq_find_close_cooperator(bfqd, bfqq,
+ bfq_io_struct_pos(io_struct, request));
+
+ BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent);
+
+ if (new_bfqq && wr_from_too_long(new_bfqq) &&
+ likely(new_bfqq != &bfqd->oom_bfqq) &&
+ bfq_may_be_close_cooperator(bfqq, new_bfqq))
+ bfq_log_bfqq(bfqd, bfqq,
+ "would have merged with bfq%d, but wr",
+ new_bfqq->pid);
+
+ if (new_bfqq && !wr_from_too_long(new_bfqq) &&
+ likely(new_bfqq != &bfqd->oom_bfqq) &&
+ bfq_may_be_close_cooperator(bfqq, new_bfqq))
+ return bfq_setup_merge(bfqq, new_bfqq);
+
+ return NULL;
+}
+
+static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
+{
+ /*
+ * If !bfqq->bic, the queue is already shared or its requests
+ * have already been redirected to a shared queue; both idle window
+ * and weight raising state have already been saved. Do nothing.
+ */
+ if (!bfqq->bic)
+ return;
+
+ bfqq->bic->saved_idle_window = bfq_bfqq_idle_window(bfqq);
+ bfqq->bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
+ bfqq->bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
+ bfqq->bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
+}
+
+static void bfq_get_bic_reference(struct bfq_queue *bfqq)
+{
+ /*
+ * If bfqq->bic has a non-NULL value, the bic to which it belongs
+ * is about to begin using a shared bfq_queue.
+ */
+ if (bfqq->bic)
+ atomic_long_inc(&bfqq->bic->icq.ioc->refcount);
+}
+
+static void
+bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
+ struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
+{
+ bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu",
+ (unsigned long) new_bfqq->pid);
+ /* Save weight raising and idle window of the merged queues */
+ bfq_bfqq_save_state(bfqq);
+ bfq_bfqq_save_state(new_bfqq);
+ if (bfq_bfqq_IO_bound(bfqq))
+ bfq_mark_bfqq_IO_bound(new_bfqq);
+ bfq_clear_bfqq_IO_bound(bfqq);
+
+ /*
+ * If bfqq is weight-raised, then let new_bfqq inherit
+ * weight-raising. To reduce false positives, neglect the case
+ * where bfqq has just been created, but has not yet made it
+ * to be weight-raised (which may happen because EQM may merge
+ * bfqq even before bfq_add_request is executed for the first
+ * time for bfqq). Handling this case would however be very
+ * easy, thanks to the flag just_created.
+ */
+ if (new_bfqq->wr_coeff == 1 && bfqq->wr_coeff > 1) {
+ new_bfqq->wr_coeff = bfqq->wr_coeff;
+ new_bfqq->wr_cur_max_time = bfqq->wr_cur_max_time;
+ new_bfqq->last_wr_start_finish = bfqq->last_wr_start_finish;
+ if (bfq_bfqq_busy(new_bfqq))
+ bfqd->wr_busy_queues++;
+ new_bfqq->entity.prio_changed = 1;
+ bfq_log_bfqq(bfqd, new_bfqq,
+ "wr start after merge with %d, rais_max_time %u",
+ bfqq->pid,
+ jiffies_to_msecs(bfqq->wr_cur_max_time));
+ }
+
+ if (bfqq->wr_coeff > 1) { /* bfqq has given its wr to new_bfqq */
+ bfqq->wr_coeff = 1;
+ bfqq->entity.prio_changed = 1;
+ if (bfq_bfqq_busy(bfqq))
+ bfqd->wr_busy_queues--;
+ }
+
+ bfq_log_bfqq(bfqd, new_bfqq, "merge_bfqqs: wr_busy %d",
+ bfqd->wr_busy_queues);
+
+ /*
+ * Grab a reference to the bic, to prevent it from being destroyed
+ * before being possibly touched by a bfq_split_bfqq().
+ */
+ bfq_get_bic_reference(bfqq);
+ bfq_get_bic_reference(new_bfqq);
+ /*
+ * Merge queues (that is, let bic redirect its requests to new_bfqq)
+ */
+ bic_set_bfqq(bic, new_bfqq, 1);
+ bfq_mark_bfqq_coop(new_bfqq);
+ /*
+ * new_bfqq now belongs to at least two bics (it is a shared queue):
+ * set new_bfqq->bic to NULL. bfqq either:
+ * - does not belong to any bic any more, and hence bfqq->bic must
+ * be set to NULL, or
+ * - is a queue whose owning bics have already been redirected to a
+ * different queue, hence the queue is destined to not belong to
+ * any bic soon and bfqq->bic is already NULL (therefore the next
+ * assignment causes no harm).
+ */
+ new_bfqq->bic = NULL;
+ bfqq->bic = NULL;
+ bfq_put_queue(bfqq);
+}
+
+static int bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
+ struct bio *bio)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_io_cq *bic;
+ struct bfq_queue *bfqq, *new_bfqq;
+
+ /*
+ * Disallow merge of a sync bio into an async request.
+ */
+ if (bfq_bio_sync(bio) && !rq_is_sync(rq))
+ return false;
+
+ /*
+ * Lookup the bfqq that this bio will be queued with. Allow
+ * merge only if rq is queued there.
+ * Queue lock is held here.
+ */
+ bic = bfq_bic_lookup(bfqd, current->io_context);
+ if (!bic)
+ return false;
+
+ bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio));
+ /*
+ * We take advantage of this function to perform an early merge
+ * of the queues of possible cooperating processes.
+ */
+ if (bfqq) {
+ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
+ if (new_bfqq) {
+ bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq);
+ /*
+ * If we get here, the bio will be queued in the
+ * shared queue, i.e., new_bfqq, so use new_bfqq
+ * to decide whether bio and rq can be merged.
+ */
+ bfqq = new_bfqq;
+ }
+ }
+
+ return bfqq == RQ_BFQQ(rq);
+}
+
+static int bfq_allow_rq_merge(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ return RQ_BFQQ(rq) == RQ_BFQQ(next);
+}
+
+/*
+ * Set the maximum time for the in-service queue to consume its
+ * budget. This prevents seeky processes from lowering the throughput.
+ * In practice, a time-slice service scheme is used with seeky
+ * processes.
+ */
+static void bfq_set_budget_timeout(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ unsigned int timeout_coeff;
+
+ if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time)
+ timeout_coeff = 1;
+ else
+ timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
+
+ bfqd->last_budget_start = ktime_get();
+
+ bfqq->budget_timeout = jiffies +
+ bfqd->bfq_timeout * timeout_coeff;
+
+ bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u",
+ jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff));
+}
+
+static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ if (bfqq) {
+ bfqg_stats_update_avg_queue_size(bfqq_group(bfqq));
+ bfq_mark_bfqq_must_alloc(bfqq);
+ bfq_clear_bfqq_fifo_expire(bfqq);
+
+ bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
+
+ BUG_ON(bfqq == bfqd->in_service_queue);
+ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
+
+ if (bfqq->wr_coeff > 1 &&
+ bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
+ time_is_before_jiffies(bfqq->budget_timeout)) {
+ /*
+ * For soft real-time queues, move the start
+ * of the weight-raising period forward by the
+ * time the queue has not received any
+ * service. Otherwise, a relatively long
+ * service delay is likely to cause the
+ * weight-raising period of the queue to end,
+ * because of the short duration of the
+ * weight-raising period of a soft real-time
+ * queue. It is worth noting that this move
+ * is not so dangerous for the other queues,
+ * because soft real-time queues are not
+ * greedy.
+ *
+ * To not add a further variable, we use the
+ * overloaded field budget_timeout to
+ * determine for how long the queue has not
+ * received service, i.e., how much time has
+ * elapsed since the queue expired. However,
+ * this is a little imprecise, because
+ * budget_timeout is set to jiffies if bfqq
+ * not only expires, but also remains with no
+ * request.
+ */
+ bfqq->last_wr_start_finish += jiffies -
+ bfqq->budget_timeout;
+ }
+
+ bfq_set_budget_timeout(bfqd, bfqq);
+ bfq_log_bfqq(bfqd, bfqq,
+ "set_in_service_queue, cur-budget = %d",
+ bfqq->entity.budget);
+ } else
+ bfq_log(bfqd, "set_in_service_queue: NULL");
+
+ bfqd->in_service_queue = bfqq;
+}
+
+/*
+ * Get and set a new queue for service.
+ */
+static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq = bfq_get_next_queue(bfqd);
+
+ __bfq_set_in_service_queue(bfqd, bfqq);
+ return bfqq;
+}
+
+static void bfq_arm_slice_timer(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq = bfqd->in_service_queue;
+ struct bfq_io_cq *bic;
+ unsigned long sl;
+
+ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
+
+ /* Processes have exited, don't wait. */
+ bic = bfqd->in_service_bic;
+ if (!bic || atomic_read(&bic->icq.ioc->active_ref) == 0)
+ return;
+
+ bfq_mark_bfqq_wait_request(bfqq);
+
+ /*
+ * We don't want to idle for seeks, but we do want to allow
+ * fair distribution of slice time for a process doing back-to-back
+ * seeks. So allow a little bit of time for him to submit a new rq.
+ *
+ * To prevent processes with (partly) seeky workloads from
+ * being too ill-treated, grant them a small fraction of the
+ * assigned budget before reducing the waiting time to
+ * BFQ_MIN_TT. This happened to help reduce latency.
+ */
+ sl = bfqd->bfq_slice_idle;
+ /*
+ * Unless the queue is being weight-raised or the scenario is
+ * asymmetric, grant only minimum idle time if the queue
+ * is seeky. A long idling is preserved for a weight-raised
+ * queue, or, more in general, in an asymemtric scenario,
+ * because a long idling is needed for guaranteeing to a queue
+ * its reserved share of the throughput (in particular, it is
+ * needed if the queue has a higher weight than some other
+ * queue).
+ */
+ if (BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 &&
+ bfq_symmetric_scenario(bfqd))
+ sl = min_t(u64, sl, BFQ_MIN_TT);
+
+ bfqd->last_idling_start = ktime_get();
+ hrtimer_start(&bfqd->idle_slice_timer, ns_to_ktime(sl),
+ HRTIMER_MODE_REL);
+ bfqg_stats_set_start_idle_time(bfqq_group(bfqq));
+ bfq_log(bfqd, "arm idle: %llu/%llu ms",
+ div_u64(sl, NSEC_PER_MSEC),
+ div_u64(bfqd->bfq_slice_idle, NSEC_PER_MSEC));
+}
+
+static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd)
+{
+ /*
+ * The max_budget calculated when autotuning is equal to the
+ * amount of sectors transferred in timeout at the
+ * estimated peak rate.
+ */
+ return bfqd->peak_rate * 1000 * jiffies_to_msecs(bfqd->bfq_timeout) >>
+ BFQ_RATE_SHIFT;
+}
+
+void update_thr_responsiveness_params(struct bfq_data *bfqd)
+{
+ int dev_type = blk_queue_nonrot(bfqd->queue);
+
+ if (bfqd->bfq_user_max_budget == 0) {
+ bfqd->bfq_max_budget =
+ bfq_calc_max_budget(bfqd);
+ BUG_ON(bfqd->bfq_max_budget < 0);
+ bfq_log(bfqd, "new max_budget = %d",
+ bfqd->bfq_max_budget);
+ }
+ if (bfqd->device_speed == BFQ_BFQD_FAST &&
+ bfqd->peak_rate < device_speed_thresh[dev_type]) {
+ bfqd->device_speed = BFQ_BFQD_SLOW;
+ bfqd->RT_prod = R_slow[dev_type] *
+ T_slow[dev_type];
+ } else if (bfqd->device_speed == BFQ_BFQD_SLOW &&
+ bfqd->peak_rate > device_speed_thresh[dev_type]) {
+ bfqd->device_speed = BFQ_BFQD_FAST;
+ bfqd->RT_prod = R_fast[dev_type] *
+ T_fast[dev_type];
+ }
+ bfq_log(bfqd,
+"dev_type %s dev_speed_class = %s (%llu sects/sec), thresh %llu setcs/sec",
+ dev_type == 0 ? "ROT" : "NONROT",
+ bfqd->device_speed == BFQ_BFQD_FAST ? "FAST" : "SLOW",
+ bfqd->device_speed == BFQ_BFQD_FAST ?
+ (1000000ULL*R_fast[dev_type])>>BFQ_RATE_SHIFT :
+ (1000000ULL*R_slow[dev_type])>>BFQ_RATE_SHIFT,
+ (1000000ULL*device_speed_thresh[dev_type])>>
+ BFQ_RATE_SHIFT);
+}
+
+/*
+ * Update the read/write peak rate (quantity used for auto-tuning) as
+ * a function of the rate at which bfqq has been served.
+ *
+ * This task is not trivial. Because of the presence of sw and hw
+ * queues between the scheduler and the logic that finally serves
+ * requests, it is hard to say when a given request is served exactly
+ * in the device. As a consequence it is hard to say what bandwidth is
+ * actually consumed by a given set of requets. On the opposite side,
+ * the dispatch time of any request is immediately available, and
+ * hence it is very easy to compute the request "dispatch rate". Yet,
+ * for the same reasons as above, the rate at which requests are
+ * dispatched over a certain time interval can vary greatly with
+ * respect to the rate at which those requests are then served. But,
+ * thanks to the limited queue size, the following convergence
+ * property holds: the number of dispatches MUST become closer and
+ * closer to the number of completions as the observation interval
+ * increases.
+ */
+void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
+{
+ u64 now_us = ktime_to_us(ktime_get());
+ u32 bw, weight, divisor;
+
+ WARN_ON(blk_rq_sectors(rq) > 2<<16);
+
+ if (bfqd->peak_rate_samples == 0)
+ goto reset_computation;
+
+ if (now_us - bfqd->last_dispatch > 200000ULL &&
+ bfqd->rq_in_driver == 0) {
+ if (bfqd->peak_rate_samples > 16 &&
+ bfqd->delta_from_first_us > 1000ULL) {
+ bfq_log(bfqd,
+ "update_disp_rate: updating&resetting delta_last %llu samples %d",
+ now_us - bfqd->last_dispatch,
+ bfqd->peak_rate_samples) ;
+ goto update_rate_and_reset;
+ } else {
+ bfq_log(bfqd,
+ "update_disp_rate: resetting delta_last %llu samples %d",
+ now_us - bfqd->last_dispatch,
+ bfqd->peak_rate_samples) ;
+ goto reset_computation;
+ }
+ }
+
+ bfqd->peak_rate_samples++;
+ if (get_sdist(bfqd->last_position, rq) < BFQQ_SEEK_THR)
+ bfqd->sequential_samples++;
+ bfqd->tot_sectors_dispatched += blk_rq_sectors(rq);
+
+ bfqd->delta_from_first_us = now_us - bfqd->first_dispatch;
+
+ bfq_log(bfqd,
+ "update_disp_rate: samples %u/%u size %llu delta_first_us %llu",
+ bfqd->peak_rate_samples, bfqd->sequential_samples,
+ bfqd->tot_sectors_dispatched, bfqd->delta_from_first_us);
+
+ if (bfqd->delta_from_first_us < BFQ_RATE_SAMPLING_INT)
+ goto update_last_values;
+
+update_rate_and_reset:
+ if (bfqd->rq_in_driver == 0)
+ bfqd->delta_from_first_us =
+ max_t(u64, bfqd->delta_from_first_us,
+ bfqd->last_completion - bfqd->first_dispatch);
+
+ BUG_ON(bfqd->delta_from_first_us == 0);
+ bw = div_u64(bfqd->tot_sectors_dispatched<<BFQ_RATE_SHIFT,
+ bfqd->delta_from_first_us);
+
+ bfq_log(bfqd,
+ "update_disp_rate: size %llu delta_first_us %llu bw %u sects/s (%d)",
+ bfqd->tot_sectors_dispatched, bfqd->delta_from_first_us,
+ (u32)((1000000ULL*(u64)bw)>>BFQ_RATE_SHIFT),
+ bw > 20<<BFQ_RATE_SHIFT);
+
+ /*
+ * Peak rate not updated if:
+ *
+ * - percentage of sequential dispatches below 2/3 of the
+ * total, and bw below peak rate
+ * - bw is unreasonably high (> 20M IOPS)
+ */
+ if ((bfqd->peak_rate_samples > 3 * bfqd->sequential_samples / 2 &&
+ bw <= bfqd->peak_rate) ||
+ bw > 20<<BFQ_RATE_SHIFT)
+ goto reset_computation;
+
+ /*
+ * If we get here, then we have to update the peak rate.
+ *
+ * Next weight runs from 0 to 8. The maximum value, 8, implies
+ * that the measured bandwidth contributes for half. 11 cannot
+ * be reached because bfqd->sequential_samples cannot become
+ * equal to bfqd->peak_rate_samples (obtained by just never
+ * incrementing bfqd->sequential_samples for the first
+ * sample).
+ */
+ weight = (9 * bfqd->sequential_samples) / bfqd->peak_rate_samples;
+
+ /*
+ * Further refine weight as a function of actual duration of
+ * the sampling interval (higher divisor means lower weight).
+ */
+ weight = min_t(u32, 8,
+ (weight * bfqd->delta_from_first_us) /
+ BFQ_RATE_SAMPLING_INT);
+
+ /*
+ * Divisor ranging from 10, minimum weight, to 2, maximum weight.
+ */
+ divisor = 10 - weight;
+ BUG_ON(divisor == 0);
+
+ bfqd->peak_rate *= divisor-1;
+ bfqd->peak_rate = div_u64(bfqd->peak_rate, divisor);
+ bw /= divisor;
+
+ bfq_log(bfqd,
+ "update_disp_rate: divisor %d tmp_peak_rate %llu tmp_bw %u",
+ divisor,
+ ((1000000ULL*bfqd->peak_rate)>>BFQ_RATE_SHIFT),
+ (u32)((1000000ULL*(u64)bw)>>BFQ_RATE_SHIFT));
+
+ BUG_ON(bfqd->peak_rate == 0);
+ BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
+
+ bfqd->peak_rate += bw;
+ update_thr_responsiveness_params(bfqd);
+
+reset_computation:
+ bfqd->first_dispatch = now_us ;
+ bfqd->peak_rate_samples = 1;
+ bfqd->sequential_samples = 0;
+ bfqd->tot_sectors_dispatched = blk_rq_sectors(rq);
+
+ bfq_log(bfqd,
+ "update_disp_rate: reset samples %u/%u size %llu",
+ bfqd->peak_rate_samples, bfqd->sequential_samples,
+ bfqd->tot_sectors_dispatched);
+
+ BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
+
+update_last_values:
+ bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
+ bfqd->last_dispatch = now_us;
+
+ bfq_log(bfqd,
+ "update_disp_rate: delta_first %lluus last_pos %llu peak_rate %llu",
+ now_us - bfqd->first_dispatch,
+ (unsigned long long) bfqd->last_position,
+ ((1000000ULL*bfqd->peak_rate)>>BFQ_RATE_SHIFT));
+}
+
+/*
+ * Move request from internal lists to the dispatch list of the request queue
+ */
+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ /*
+ * For consistency, the next instruction should have been executed
+ * after removing the request from the queue and dispatching it.
+ * We execute instead this instruction before bfq_remove_request()
+ * (and hence introduce a temporary inconsistency), for efficiency.
+ * In fact, in a forced_dispatch, this prevents two counters related
+ * to bfqq->dispatched to risk to be uselessly decremented if bfqq
+ * is not in service, and then to be incremented again after
+ * incrementing bfqq->dispatched.
+ */
+ bfqq->dispatched++;
+ bfq_update_peak_rate(q->elevator->elevator_data, rq);
+
+ bfq_remove_request(rq);
+ elv_dispatch_sort(q, rq);
+}
+
+/*
+ * Return expired entry, or NULL to just start from scratch in rbtree.
+ */
+static struct request *bfq_check_fifo(struct bfq_queue *bfqq)
+{
+ struct request *rq = NULL;
+
+ if (bfq_bfqq_fifo_expire(bfqq))
+ return NULL;
+
+ bfq_mark_bfqq_fifo_expire(bfqq);
+
+ if (list_empty(&bfqq->fifo))
+ return NULL;
+
+ rq = rq_entry_fifo(bfqq->fifo.next);
+
+ if (ktime_get_ns() < rq->fifo_time)
+ return NULL;
+
+ return rq;
+}
+
+static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ BUG_ON(bfqq != bfqd->in_service_queue);
+
+ __bfq_bfqd_reset_in_service(bfqd);
+
+ /*
+ * If this bfqq is shared between multiple processes, check
+ * to make sure that those processes are still issuing I/Os
+ * within the mean seek distance. If not, it may be time to
+ * break the queues apart again.
+ */
+ if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq))
+ bfq_mark_bfqq_split_coop(bfqq);
+
+ if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ if (bfqq->dispatched == 0)
+ /*
+ * Overloading budget_timeout field to store
+ * the time at which the queue remains with no
+ * backlog and no outstanding request; used by
+ * the weight-raising mechanism.
+ */
+ bfqq->budget_timeout = jiffies;
+
+ bfq_del_bfqq_busy(bfqd, bfqq, 1);
+ } else {
+ bfq_activate_bfqq(bfqd, bfqq);
+ /*
+ * Resort priority tree of potential close cooperators.
+ */
+ bfq_pos_tree_add_move(bfqd, bfqq);
+ }
+}
+
+/**
+ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior.
+ * @bfqd: device data.
+ * @bfqq: queue to update.
+ * @reason: reason for expiration.
+ *
+ * Handle the feedback on @bfqq budget at queue expiration.
+ * See the body for detailed comments.
+ */
+static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ enum bfqq_expiration reason)
+{
+ struct request *next_rq;
+ int budget, min_budget;
+
+ BUG_ON(bfqq != bfqd->in_service_queue);
+
+ min_budget = bfq_min_budget(bfqd);
+
+ if (bfqq->wr_coeff == 1)
+ budget = bfqq->max_budget;
+ else /*
+ * Use a constant, low budget for weight-raised queues,
+ * to help achieve a low latency. Keep it slightly higher
+ * than the minimum possible budget, to cause a little
+ * bit fewer expirations.
+ */
+ budget = 2 * min_budget;
+
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d",
+ bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %d, min budg %d",
+ budget, bfq_min_budget(bfqd));
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
+ bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
+
+ if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) {
+ switch (reason) {
+ /*
+ * Caveat: in all the following cases we trade latency
+ * for throughput.
+ */
+ case BFQ_BFQQ_TOO_IDLE:
+ /*
+ * This is the only case where we may reduce
+ * the budget: if there is no request of the
+ * process still waiting for completion, then
+ * we assume (tentatively) that the timer has
+ * expired because the batch of requests of
+ * the process could have been served with a
+ * smaller budget. Hence, betting that
+ * process will behave in the same way when it
+ * becomes backlogged again, we reduce its
+ * next budget. As long as we guess right,
+ * this budget cut reduces the latency
+ * experienced by the process.
+ *
+ * However, if there are still outstanding
+ * requests, then the process may have not yet
+ * issued its next request just because it is
+ * still waiting for the completion of some of
+ * the still outstanding ones. So in this
+ * subcase we do not reduce its budget, on the
+ * contrary we increase it to possibly boost
+ * the throughput, as discussed in the
+ * comments to the BUDGET_TIMEOUT case.
+ */
+ if (bfqq->dispatched > 0) /* still outstanding reqs */
+ budget = min(budget * 2, bfqd->bfq_max_budget);
+ else {
+ if (budget > 5 * min_budget)
+ budget -= 4 * min_budget;
+ else
+ budget = min_budget;
+ }
+ break;
+ case BFQ_BFQQ_BUDGET_TIMEOUT:
+ /*
+ * We double the budget here because it gives
+ * the chance to boost the throughput if this
+ * is not a seeky process (and has bumped into
+ * this timeout because of, e.g., ZBR).
+ */
+ budget = min(budget * 2, bfqd->bfq_max_budget);
+ break;
+ case BFQ_BFQQ_BUDGET_EXHAUSTED:
+ /*
+ * The process still has backlog, and did not
+ * let either the budget timeout or the disk
+ * idling timeout expire. Hence it is not
+ * seeky, has a short thinktime and may be
+ * happy with a higher budget too. So
+ * definitely increase the budget of this good
+ * candidate to boost the disk throughput.
+ */
+ budget = min(budget * 4, bfqd->bfq_max_budget);
+ break;
+ case BFQ_BFQQ_NO_MORE_REQUESTS:
+ /*
+ * For queues that expire for this reason, it
+ * is particularly important to keep the
+ * budget close to the actual service they
+ * need. Doing so reduces the timestamp
+ * misalignment problem described in the
+ * comments in the body of
+ * __bfq_activate_entity. In fact, suppose
+ * that a queue systematically expires for
+ * BFQ_BFQQ_NO_MORE_REQUESTS and presents a
+ * new request in time to enjoy timestamp
+ * back-shifting. The larger the budget of the
+ * queue is with respect to the service the
+ * queue actually requests in each service
+ * slot, the more times the queue can be
+ * reactivated with the same virtual finish
+ * time. It follows that, even if this finish
+ * time is pushed to the system virtual time
+ * to reduce the consequent timestamp
+ * misalignment, the queue unjustly enjoys for
+ * many re-activations a lower finish time
+ * than all newly activated queues.
+ *
+ * The service needed by bfqq is measured
+ * quite precisely by bfqq->entity.service.
+ * Since bfqq does not enjoy device idling,
+ * bfqq->entity.service is equal to the number
+ * of sectors that the process associated with
+ * bfqq requested to read/write before waiting
+ * for request completions, or blocking for
+ * other reasons.
+ */
+ budget = max_t(int, bfqq->entity.service, min_budget);
+ break;
+ default:
+ return;
+ }
+ } else if (!bfq_bfqq_sync(bfqq))
+ /*
+ * Async queues get always the maximum possible
+ * budget, as for them we do not care about latency
+ * (in addition, their ability to dispatch is limited
+ * by the charging factor).
+ */
+ budget = bfqd->bfq_max_budget;
+
+ bfqq->max_budget = budget;
+
+ if (bfqd->budgets_assigned >= bfq_stats_min_budgets &&
+ !bfqd->bfq_user_max_budget)
+ bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget);
+
+ /*
+ * If there is still backlog, then assign a new budget, making
+ * sure that it is large enough for the next request. Since
+ * the finish time of bfqq must be kept in sync with the
+ * budget, be sure to call __bfq_bfqq_expire() *after* this
+ * update.
+ *
+ * If there is no backlog, then no need to update the budget;
+ * it will be updated on the arrival of a new request.
+ */
+ next_rq = bfqq->next_rq;
+ if (next_rq) {
+ BUG_ON(reason == BFQ_BFQQ_TOO_IDLE ||
+ reason == BFQ_BFQQ_NO_MORE_REQUESTS);
+ bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+ BUG_ON(!bfq_bfqq_busy(bfqq));
+ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
+ }
+
+ bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d",
+ next_rq ? blk_rq_sectors(next_rq) : 0,
+ bfqq->entity.budget);
+}
+
+/*
+ * Check whether the process associated with bfqq is "slow". Return
+ * true if the process is slow. The slow flag is used, in addition to
+ * the budget timeout, to reduce the amount of service provided to
+ * seeky processes, and hence reduce their chances to lower the
+ * throughput. More details in the body of the function.
+ *
+ * An important observation is in order: with devices with internal
+ * queues, it is hard if ever possible to know when and for how long
+ * an I/O request is processed by the device (apart from the trivial
+ * I/O pattern where a new request is dispatched only after the
+ * previous one has been completed). This makes it hard to evaluate
+ * the real rate at which the I/O requests of each bfq_queue are
+ * served. In fact, for an I/O scheduler like BFQ, serving a
+ * bfq_queue means just dispatching its requests during its service
+ * slot, i.e., until the budget of the queue is exhausted, or the
+ * queue remains idle, or, finally, a timeout fires. But, during the
+ * service slot of a bfq_queue, the device may be still processing
+ * requests of bfq_queues served in previous service slots. On the
+ * opposite end, the requests of the in-service bfq_queue may be
+ * completed after the service slot of the queue finishes. Anyway,
+ * unless more sophisticated solutions are used (where possible), the
+ * sum of the sizes of the requests dispatched during the service slot
+ * of a bfq_queue is probably the only approximation available for the
+ * service received by the bfq_queue during its service slot. And,
+ * this sum is the quantity used in this function to evaluate the I/O
+ * speed of a process.
+ */
+static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ bool compensate, enum bfqq_expiration reason,
+ unsigned long *delta_ms)
+{
+ ktime_t delta_ktime;
+ u64 delta_usecs;
+ bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */
+
+ if (!bfq_bfqq_sync(bfqq))
+ return false;
+
+ if (compensate)
+ delta_ktime = bfqd->last_idling_start;
+ else
+ delta_ktime = ktime_get();
+ delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start);
+ delta_usecs = ktime_to_us(delta_ktime);
+
+ /* Don't trust short/unrealistic values. */
+ if (delta_usecs < 1000 || delta_usecs >= LONG_MAX) {
+ if (blk_queue_nonrot(bfqd->queue))
+ *delta_ms = BFQ_MIN_TT; /*
+ * give same worst-case
+ * guarantees as
+ * idling for seeky
+ */
+ else /* Charge at least one seek */
+ *delta_ms = jiffies_to_msecs(bfq_slice_idle);
+ return slow;
+ }
+
+ /*
+ * Use only long (> 20ms) intervals to filter out spikes for
+ * the peak rate estimation.
+ */
+ if (delta_usecs > 20000) {
+ /*
+ * Caveat: processes doing IO in the slower disk zones
+ * tend to be slow(er) even if not seeky. In this
+ * respect, the estimated peak rate is likely to be an
+ * average over the disk surface. Accordingly, to not
+ * be too harsh with unlucky processes, a process is
+ * deemed slow only if its bw has been lower than half
+ * of the estimated peak rate.
+ */
+ slow = bfqq->entity.service < bfqd->bfq_max_budget / 2;
+ bfq_log(bfqd, "bfq_bfqq_is_slow: relative bw %d/%d",
+ bfqq->entity.service, bfqd->bfq_max_budget);
+ }
+
+ bfq_log_bfqq(bfqd, bfqq, "bfq_bfqq_is_slow: slow %d", slow);
+
+ return slow;
+}
+
+/*
+ * To be deemed as soft real-time, an application must meet two
+ * requirements. First, the application must not require an average
+ * bandwidth higher than the approximate bandwidth required to playback or
+ * record a compressed high-definition video.
+ * The next function is invoked on the completion of the last request of a
+ * batch, to compute the next-start time instant, soft_rt_next_start, such
+ * that, if the next request of the application does not arrive before
+ * soft_rt_next_start, then the above requirement on the bandwidth is met.
+ *
+ * The second requirement is that the request pattern of the application is
+ * isochronous, i.e., that, after issuing a request or a batch of requests,
+ * the application stops issuing new requests until all its pending requests
+ * have been completed. After that, the application may issue a new batch,
+ * and so on.
+ * For this reason the next function is invoked to compute
+ * soft_rt_next_start only for applications that meet this requirement,
+ * whereas soft_rt_next_start is set to infinity for applications that do
+ * not.
+ *
+ * Unfortunately, even a greedy application may happen to behave in an
+ * isochronous way if the CPU load is high. In fact, the application may
+ * stop issuing requests while the CPUs are busy serving other processes,
+ * then restart, then stop again for a while, and so on. In addition, if
+ * the disk achieves a low enough throughput with the request pattern
+ * issued by the application (e.g., because the request pattern is random
+ * and/or the device is slow), then the application may meet the above
+ * bandwidth requirement too. To prevent such a greedy application to be
+ * deemed as soft real-time, a further rule is used in the computation of
+ * soft_rt_next_start: soft_rt_next_start must be higher than the current
+ * time plus the maximum time for which the arrival of a request is waited
+ * for when a sync queue becomes idle, namely bfqd->bfq_slice_idle.
+ * This filters out greedy applications, as the latter issue instead their
+ * next request as soon as possible after the last one has been completed
+ * (in contrast, when a batch of requests is completed, a soft real-time
+ * application spends some time processing data).
+ *
+ * Unfortunately, the last filter may easily generate false positives if
+ * only bfqd->bfq_slice_idle is used as a reference time interval and one
+ * or both the following cases occur:
+ * 1) HZ is so low that the duration of a jiffy is comparable to or higher
+ * than bfqd->bfq_slice_idle. This happens, e.g., on slow devices with
+ * HZ=100.
+ * 2) jiffies, instead of increasing at a constant rate, may stop increasing
+ * for a while, then suddenly 'jump' by several units to recover the lost
+ * increments. This seems to happen, e.g., inside virtual machines.
+ * To address this issue, we do not use as a reference time interval just
+ * bfqd->bfq_slice_idle, but bfqd->bfq_slice_idle plus a few jiffies. In
+ * particular we add the minimum number of jiffies for which the filter
+ * seems to be quite precise also in embedded systems and KVM/QEMU virtual
+ * machines.
+ */
+static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ bfq_log_bfqq(bfqd, bfqq,
+"softrt_next_start: service_blkg %lu soft_rate %u sects/sec interval %u",
+ bfqq->service_from_backlogged,
+ bfqd->bfq_wr_max_softrt_rate,
+ jiffies_to_msecs(HZ * bfqq->service_from_backlogged /
+ bfqd->bfq_wr_max_softrt_rate));
+
+ return max(bfqq->last_idle_bklogged +
+ HZ * bfqq->service_from_backlogged /
+ bfqd->bfq_wr_max_softrt_rate,
+ jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
+}
+
+/*
+ * Return the farthest future time instant according to jiffies
+ * macros.
+ */
+static unsigned long bfq_greatest_from_now(void)
+{
+ return jiffies + MAX_JIFFY_OFFSET;
+}
+
+/*
+ * Return the farthest past time instant according to jiffies
+ * macros.
+ */
+static unsigned long bfq_smallest_from_now(void)
+{
+ return jiffies - MAX_JIFFY_OFFSET;
+}
+
+/**
+ * bfq_bfqq_expire - expire a queue.
+ * @bfqd: device owning the queue.
+ * @bfqq: the queue to expire.
+ * @compensate: if true, compensate for the time spent idling.
+ * @reason: the reason causing the expiration.
+ *
+ * If the process associated with bfqq does slow I/O (e.g., because it
+ * issues random requests), we charge bfqq with the time it has been
+ * in service instead of the service it has received (see
+ * bfq_bfqq_charge_time for details on how this goal is achieved). As
+ * a consequence, bfqq will typically get higher timestamps upon
+ * reactivation, and hence it will be rescheduled as if it had
+ * received more service than what it has actually received. In the
+ * end, bfqq receives less service in proportion to how slowly its
+ * associated process consumes its budgets (and hence how seriously it
+ * tends to lower the throughput). In addition, this time-charging
+ * strategy guarantees time fairness among slow processes. In
+ * contrast, if the process associated with bfqq is not slow, we
+ * charge bfqq exactly with the service it has received.
+ *
+ * Charging time to the first type of queues and the exact service to
+ * the other has the effect of using the WF2Q+ policy to schedule the
+ * former on a timeslice basis, without violating service domain
+ * guarantees among the latter.
+ */
+static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ bool compensate,
+ enum bfqq_expiration reason)
+{
+ bool slow;
+ unsigned long delta = 0;
+ struct bfq_entity *entity = &bfqq->entity;
+
+ BUG_ON(bfqq != bfqd->in_service_queue);
+
+ /*
+ * Check whether the process is slow (see bfq_bfqq_is_slow).
+ */
+ slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta);
+
+ /*
+ * Increase service_from_backlogged before next statement,
+ * because the possible next invocation of
+ * bfq_bfqq_charge_time would likely inflate
+ * entity->service. In contrast, service_from_backlogged must
+ * contain real service, to enable the soft real-time
+ * heuristic to correctly compute the bandwidth consumed by
+ * bfqq.
+ */
+ bfqq->service_from_backlogged += entity->service;
+
+ /*
+ * As above explained, charge slow (typically seeky) and
+ * timed-out queues with the time and not the service
+ * received, to favor sequential workloads.
+ *
+ * Processes doing I/O in the slower disk zones will tend to
+ * be slow(er) even if not seeky. Therefore, since the
+ * estimated peak rate is actually an average over the disk
+ * surface, these processes may timeout just for bad luck. To
+ * avoid punishing them, do not charge time to processes that
+ * succeeded in consuming at least 2/3 of their budget. This
+ * allows BFQ to preserve enough elasticity to still perform
+ * bandwidth, and not time, distribution with little unlucky
+ * or quasi-sequential processes.
+ */
+ if (bfqq->wr_coeff == 1 &&
+ (slow ||
+ (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
+ bfq_bfqq_budget_left(bfqq) >= entity->budget / 3)))
+ bfq_bfqq_charge_time(bfqd, bfqq, delta);
+
+ BUG_ON(bfqq->entity.budget < bfqq->entity.service);
+
+ if (reason == BFQ_BFQQ_TOO_IDLE &&
+ entity->service <= 2 * entity->budget / 10)
+ bfq_clear_bfqq_IO_bound(bfqq);
+
+ if (bfqd->low_latency && bfqq->wr_coeff == 1)
+ bfqq->last_wr_start_finish = jiffies;
+
+ if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 &&
+ RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ /*
+ * If we get here, and there are no outstanding
+ * requests, then the request pattern is isochronous
+ * (see the comments on the function
+ * bfq_bfqq_softrt_next_start()). Thus we can compute
+ * soft_rt_next_start. If, instead, the queue still
+ * has outstanding requests, then we have to wait for
+ * the completion of all the outstanding requests to
+ * discover whether the request pattern is actually
+ * isochronous.
+ */
+ BUG_ON(bfqd->busy_queues < 1);
+ if (bfqq->dispatched == 0) {
+ bfqq->soft_rt_next_start =
+ bfq_bfqq_softrt_next_start(bfqd, bfqq);
+ bfq_log_bfqq(bfqd, bfqq, "new soft_rt_next %lu",
+ bfqq->soft_rt_next_start);
+ } else {
+ /*
+ * The application is still waiting for the
+ * completion of one or more requests:
+ * prevent it from possibly being incorrectly
+ * deemed as soft real-time by setting its
+ * soft_rt_next_start to infinity. In fact,
+ * without this assignment, the application
+ * would be incorrectly deemed as soft
+ * real-time if:
+ * 1) it issued a new request before the
+ * completion of all its in-flight
+ * requests, and
+ * 2) at that time, its soft_rt_next_start
+ * happened to be in the past.
+ */
+ bfqq->soft_rt_next_start =
+ bfq_greatest_from_now();
+ /*
+ * Schedule an update of soft_rt_next_start to when
+ * the task may be discovered to be isochronous.
+ */
+ bfq_mark_bfqq_softrt_update(bfqq);
+ }
+ }
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "expire (%d, slow %d, num_disp %d, idle_win %d, weight %d)",
+ reason, slow, bfqq->dispatched,
+ bfq_bfqq_idle_window(bfqq), entity->weight);
+
+ /*
+ * Increase, decrease or leave budget unchanged according to
+ * reason.
+ */
+ BUG_ON(bfqq->entity.budget < bfqq->entity.service);
+ __bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
+ BUG_ON(bfqq->next_rq == NULL &&
+ bfqq->entity.budget < bfqq->entity.service);
+ __bfq_bfqq_expire(bfqd, bfqq);
+
+ BUG_ON(!bfq_bfqq_busy(bfqq) && reason == BFQ_BFQQ_BUDGET_EXHAUSTED &&
+ !bfq_class_idle(bfqq));
+
+ if (!bfq_bfqq_busy(bfqq) &&
+ reason != BFQ_BFQQ_BUDGET_TIMEOUT &&
+ reason != BFQ_BFQQ_BUDGET_EXHAUSTED)
+ bfq_mark_bfqq_non_blocking_wait_rq(bfqq);
+}
+
+/*
+ * Budget timeout is not implemented through a dedicated timer, but
+ * just checked on request arrivals and completions, as well as on
+ * idle timer expirations.
+ */
+static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
+{
+ return time_is_before_eq_jiffies(bfqq->budget_timeout);
+}
+
+/*
+ * If we expire a queue that is actively waiting (i.e., with the
+ * device idled) for the arrival of a new request, then we may incur
+ * the timestamp misalignment problem described in the body of the
+ * function __bfq_activate_entity. Hence we return true only if this
+ * condition does not hold, or if the queue is slow enough to deserve
+ * only to be kicked off for preserving a high throughput.
+ */
+static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
+{
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "may_budget_timeout: wait_request %d left %d timeout %d",
+ bfq_bfqq_wait_request(bfqq),
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3,
+ bfq_bfqq_budget_timeout(bfqq));
+
+ return (!bfq_bfqq_wait_request(bfqq) ||
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3)
+ &&
+ bfq_bfqq_budget_timeout(bfqq);
+}
+
+/*
+ * For a queue that becomes empty, device idling is allowed only if
+ * this function returns true for that queue. As a consequence, since
+ * device idling plays a critical role for both throughput boosting
+ * and service guarantees, the return value of this function plays a
+ * critical role as well.
+ *
+ * In a nutshell, this function returns true only if idling is
+ * beneficial for throughput or, even if detrimental for throughput,
+ * idling is however necessary to preserve service guarantees (low
+ * latency, desired throughput distribution, ...). In particular, on
+ * NCQ-capable devices, this function tries to return false, so as to
+ * help keep the drives' internal queues full, whenever this helps the
+ * device boost the throughput without causing any service-guarantee
+ * issue.
+ *
+ * In more detail, the return value of this function is obtained by,
+ * first, computing a number of boolean variables that take into
+ * account throughput and service-guarantee issues, and, then,
+ * combining these variables in a logical expression. Most of the
+ * issues taken into account are not trivial. We discuss these issues
+ * while introducing the variables.
+ */
+static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
+{
+ struct bfq_data *bfqd = bfqq->bfqd;
+ bool idling_boosts_thr, idling_boosts_thr_without_issues,
+ idling_needed_for_service_guarantees,
+ asymmetric_scenario;
+
+ if (bfqd->strict_guarantees)
+ return true;
+
+ /*
+ * The next variable takes into account the cases where idling
+ * boosts the throughput.
+ *
+ * The value of the variable is computed considering, first, that
+ * idling is virtually always beneficial for the throughput if:
+ * (a) the device is not NCQ-capable, or
+ * (b) regardless of the presence of NCQ, the device is rotational
+ * and the request pattern for bfqq is I/O-bound and sequential.
+ *
+ * Secondly, and in contrast to the above item (b), idling an
+ * NCQ-capable flash-based device would not boost the
+ * throughput even with sequential I/O; rather it would lower
+ * the throughput in proportion to how fast the device
+ * is. Accordingly, the next variable is true if any of the
+ * above conditions (a) and (b) is true, and, in particular,
+ * happens to be false if bfqd is an NCQ-capable flash-based
+ * device.
+ */
+ idling_boosts_thr = !bfqd->hw_tag ||
+ (!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) &&
+ bfq_bfqq_idle_window(bfqq));
+
+ /*
+ * The value of the next variable,
+ * idling_boosts_thr_without_issues, is equal to that of
+ * idling_boosts_thr, unless a special case holds. In this
+ * special case, described below, idling may cause problems to
+ * weight-raised queues.
+ *
+ * When the request pool is saturated (e.g., in the presence
+ * of write hogs), if the processes associated with
+ * non-weight-raised queues ask for requests at a lower rate,
+ * then processes associated with weight-raised queues have a
+ * higher probability to get a request from the pool
+ * immediately (or at least soon) when they need one. Thus
+ * they have a higher probability to actually get a fraction
+ * of the device throughput proportional to their high
+ * weight. This is especially true with NCQ-capable drives,
+ * which enqueue several requests in advance, and further
+ * reorder internally-queued requests.
+ *
+ * For this reason, we force to false the value of
+ * idling_boosts_thr_without_issues if there are weight-raised
+ * busy queues. In this case, and if bfqq is not weight-raised,
+ * this guarantees that the device is not idled for bfqq (if,
+ * instead, bfqq is weight-raised, then idling will be
+ * guaranteed by another variable, see below). Combined with
+ * the timestamping rules of BFQ (see [1] for details), this
+ * behavior causes bfqq, and hence any sync non-weight-raised
+ * queue, to get a lower number of requests served, and thus
+ * to ask for a lower number of requests from the request
+ * pool, before the busy weight-raised queues get served
+ * again. This often mitigates starvation problems in the
+ * presence of heavy write workloads and NCQ, thereby
+ * guaranteeing a higher application and system responsiveness
+ * in these hostile scenarios.
+ */
+ idling_boosts_thr_without_issues = idling_boosts_thr &&
+ bfqd->wr_busy_queues == 0;
+
+ /*
+ * There is then a case where idling must be performed not
+ * for throughput concerns, but to preserve service
+ * guarantees.
+ *
+ * To introduce this case, we can note that allowing the drive
+ * to enqueue more than one request at a time, and hence
+ * delegating de facto final scheduling decisions to the
+ * drive's internal scheduler, entails loss of control on the
+ * actual request service order. In particular, the critical
+ * situation is when requests from different processes happen
+ * to be present, at the same time, in the internal queue(s)
+ * of the drive. In such a situation, the drive, by deciding
+ * the service order of the internally-queued requests, does
+ * determine also the actual throughput distribution among
+ * these processes. But the drive typically has no notion or
+ * concern about per-process throughput distribution, and
+ * makes its decisions only on a per-request basis. Therefore,
+ * the service distribution enforced by the drive's internal
+ * scheduler is likely to coincide with the desired
+ * device-throughput distribution only in a completely
+ * symmetric scenario where:
+ * (i) each of these processes must get the same throughput as
+ * the others;
+ * (ii) all these processes have the same I/O pattern
+ * (either sequential or random).
+ * In fact, in such a scenario, the drive will tend to treat
+ * the requests of each of these processes in about the same
+ * way as the requests of the others, and thus to provide
+ * each of these processes with about the same throughput
+ * (which is exactly the desired throughput distribution). In
+ * contrast, in any asymmetric scenario, device idling is
+ * certainly needed to guarantee that bfqq receives its
+ * assigned fraction of the device throughput (see [1] for
+ * details).
+ *
+ * We address this issue by controlling, actually, only the
+ * symmetry sub-condition (i), i.e., provided that
+ * sub-condition (i) holds, idling is not performed,
+ * regardless of whether sub-condition (ii) holds. In other
+ * words, only if sub-condition (i) holds, then idling is
+ * allowed, and the device tends to be prevented from queueing
+ * many requests, possibly of several processes. The reason
+ * for not controlling also sub-condition (ii) is that we
+ * exploit preemption to preserve guarantees in case of
+ * symmetric scenarios, even if (ii) does not hold, as
+ * explained in the next two paragraphs.
+ *
+ * Even if a queue, say Q, is expired when it remains idle, Q
+ * can still preempt the new in-service queue if the next
+ * request of Q arrives soon (see the comments on
+ * bfq_bfqq_update_budg_for_activation). If all queues and
+ * groups have the same weight, this form of preemption,
+ * combined with the hole-recovery heuristic described in the
+ * comments on function bfq_bfqq_update_budg_for_activation,
+ * are enough to preserve a correct bandwidth distribution in
+ * the mid term, even without idling. In fact, even if not
+ * idling allows the internal queues of the device to contain
+ * many requests, and thus to reorder requests, we can rather
+ * safely assume that the internal scheduler still preserves a
+ * minimum of mid-term fairness. The motivation for using
+ * preemption instead of idling is that, by not idling,
+ * service guarantees are preserved without minimally
+ * sacrificing throughput. In other words, both a high
+ * throughput and its desired distribution are obtained.
+ *
+ * More precisely, this preemption-based, idleless approach
+ * provides fairness in terms of IOPS, and not sectors per
+ * second. This can be seen with a simple example. Suppose
+ * that there are two queues with the same weight, but that
+ * the first queue receives requests of 8 sectors, while the
+ * second queue receives requests of 1024 sectors. In
+ * addition, suppose that each of the two queues contains at
+ * most one request at a time, which implies that each queue
+ * always remains idle after it is served. Finally, after
+ * remaining idle, each queue receives very quickly a new
+ * request. It follows that the two queues are served
+ * alternatively, preempting each other if needed. This
+ * implies that, although both queues have the same weight,
+ * the queue with large requests receives a service that is
+ * 1024/8 times as high as the service received by the other
+ * queue.
+ *
+ * On the other hand, device idling is performed, and thus
+ * pure sector-domain guarantees are provided, for the
+ * following queues, which are likely to need stronger
+ * throughput guarantees: weight-raised queues, and queues
+ * with a higher weight than other queues. When such queues
+ * are active, sub-condition (i) is false, which triggers
+ * device idling.
+ *
+ * According to the above considerations, the next variable is
+ * true (only) if sub-condition (i) holds. To compute the
+ * value of this variable, we not only use the return value of
+ * the function bfq_symmetric_scenario(), but also check
+ * whether bfqq is being weight-raised, because
+ * bfq_symmetric_scenario() does not take into account also
+ * weight-raised queues (see comments on
+ * bfq_weights_tree_add()).
+ *
+ * As a side note, it is worth considering that the above
+ * device-idling countermeasures may however fail in the
+ * following unlucky scenario: if idling is (correctly)
+ * disabled in a time period during which all symmetry
+ * sub-conditions hold, and hence the device is allowed to
+ * enqueue many requests, but at some later point in time some
+ * sub-condition stops to hold, then it may become impossible
+ * to let requests be served in the desired order until all
+ * the requests already queued in the device have been served.
+ */
+ asymmetric_scenario = bfqq->wr_coeff > 1 ||
+ !bfq_symmetric_scenario(bfqd);
+
+ /*
+ * Finally, there is a case where maximizing throughput is the
+ * best choice even if it may cause unfairness toward
+ * bfqq. Such a case is when bfqq became active in a burst of
+ * queue activations. Queues that became active during a large
+ * burst benefit only from throughput, as discussed in the
+ * comments on bfq_handle_burst. Thus, if bfqq became active
+ * in a burst and not idling the device maximizes throughput,
+ * then the device must no be idled, because not idling the
+ * device provides bfqq and all other queues in the burst with
+ * maximum benefit. Combining this and the above case, we can
+ * now establish when idling is actually needed to preserve
+ * service guarantees.
+ */
+ idling_needed_for_service_guarantees =
+ asymmetric_scenario && !bfq_bfqq_in_large_burst(bfqq);
+
+ /*
+ * We have now all the components we need to compute the return
+ * value of the function, which is true only if both the following
+ * conditions hold:
+ * 1) bfqq is sync, because idling make sense only for sync queues;
+ * 2) idling either boosts the throughput (without issues), or
+ * is necessary to preserve service guarantees.
+ */
+ bfq_log_bfqq(bfqd, bfqq, "may_idle: sync %d idling_boosts_thr %d",
+ bfq_bfqq_sync(bfqq), idling_boosts_thr);
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "may_idle: wr_busy %d boosts %d IO-bound %d guar %d",
+ bfqd->wr_busy_queues,
+ idling_boosts_thr_without_issues,
+ bfq_bfqq_IO_bound(bfqq),
+ idling_needed_for_service_guarantees);
+
+ return bfq_bfqq_sync(bfqq) &&
+ (idling_boosts_thr_without_issues ||
+ idling_needed_for_service_guarantees);
+}
+
+/*
+ * If the in-service queue is empty but the function bfq_bfqq_may_idle
+ * returns true, then:
+ * 1) the queue must remain in service and cannot be expired, and
+ * 2) the device must be idled to wait for the possible arrival of a new
+ * request for the queue.
+ * See the comments on the function bfq_bfqq_may_idle for the reasons
+ * why performing device idling is the best choice to boost the throughput
+ * and preserve service guarantees when bfq_bfqq_may_idle itself
+ * returns true.
+ */
+static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)
+{
+ struct bfq_data *bfqd = bfqq->bfqd;
+
+ return RB_EMPTY_ROOT(&bfqq->sort_list) && bfqd->bfq_slice_idle != 0 &&
+ bfq_bfqq_may_idle(bfqq);
+}
+
+/*
+ * Select a queue for service. If we have a current queue in service,
+ * check whether to continue servicing it, or retrieve and set a new one.
+ */
+static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq;
+ struct request *next_rq;
+ enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT;
+
+ bfqq = bfqd->in_service_queue;
+ if (!bfqq)
+ goto new_queue;
+
+ bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue");
+
+ if (bfq_may_expire_for_budg_timeout(bfqq) &&
+ !hrtimer_active(&bfqd->idle_slice_timer) &&
+ !bfq_bfqq_must_idle(bfqq))
+ goto expire;
+
+ next_rq = bfqq->next_rq;
+ /*
+ * If bfqq has requests queued and it has enough budget left to
+ * serve them, keep the queue, otherwise expire it.
+ */
+ if (next_rq) {
+ if (bfq_serv_to_charge(next_rq, bfqq) >
+ bfq_bfqq_budget_left(bfqq)) {
+ reason = BFQ_BFQQ_BUDGET_EXHAUSTED;
+ goto expire;
+ } else {
+ /*
+ * The idle timer may be pending because we may
+ * not disable disk idling even when a new request
+ * arrives.
+ */
+ if (bfq_bfqq_wait_request(bfqq)) {
+ BUG_ON(!hrtimer_active(&bfqd->idle_slice_timer));
+ /*
+ * If we get here: 1) at least a new request
+ * has arrived but we have not disabled the
+ * timer because the request was too small,
+ * 2) then the block layer has unplugged
+ * the device, causing the dispatch to be
+ * invoked.
+ *
+ * Since the device is unplugged, now the
+ * requests are probably large enough to
+ * provide a reasonable throughput.
+ * So we disable idling.
+ */
+ bfq_clear_bfqq_wait_request(bfqq);
+ hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
+ bfqg_stats_update_idle_time(bfqq_group(bfqq));
+ }
+ goto keep_queue;
+ }
+ }
+
+ /*
+ * No requests pending. However, if the in-service queue is idling
+ * for a new request, or has requests waiting for a completion and
+ * may idle after their completion, then keep it anyway.
+ */
+ if (hrtimer_active(&bfqd->idle_slice_timer) ||
+ (bfqq->dispatched != 0 && bfq_bfqq_may_idle(bfqq))) {
+ bfqq = NULL;
+ goto keep_queue;
+ }
+
+ reason = BFQ_BFQQ_NO_MORE_REQUESTS;
+expire:
+ bfq_bfqq_expire(bfqd, bfqq, false, reason);
+new_queue:
+ bfqq = bfq_set_in_service_queue(bfqd);
+ bfq_log(bfqd, "select_queue: new queue %d returned",
+ bfqq ? bfqq->pid : 0);
+keep_queue:
+ return bfqq;
+}
+
+static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */
+ bfq_log_bfqq(bfqd, bfqq,
+ "raising period dur %u/%u msec, old coeff %u, w %d(%d)",
+ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
+ jiffies_to_msecs(bfqq->wr_cur_max_time),
+ bfqq->wr_coeff,
+ bfqq->entity.weight, bfqq->entity.orig_weight);
+
+ BUG_ON(bfqq != bfqd->in_service_queue && entity->weight !=
+ entity->orig_weight * bfqq->wr_coeff);
+ if (entity->prio_changed)
+ bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change");
+
+ /*
+ * If the queue was activated in a burst, or too much
+ * time has elapsed from the beginning of this
+ * weight-raising period, then end weight raising.
+ */
+ if (bfq_bfqq_in_large_burst(bfqq) ||
+ time_is_before_jiffies(bfqq->last_wr_start_finish +
+ bfqq->wr_cur_max_time)) {
+ bfqq->last_wr_start_finish = jiffies;
+ bfq_log_bfqq(bfqd, bfqq,
+ "wrais ending at %lu, rais_max_time %u",
+ bfqq->last_wr_start_finish,
+ jiffies_to_msecs(bfqq->wr_cur_max_time));
+ bfq_bfqq_end_wr(bfqq);
+ }
+ }
+ /* Update weight both if it must be raised and if it must be lowered */
+ if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1))
+ __bfq_entity_update_weight_prio(
+ bfq_entity_service_tree(entity),
+ entity);
+}
+
+/*
+ * Dispatch one request from bfqq, moving it to the request queue
+ * dispatch list.
+ */
+static int bfq_dispatch_request(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ int dispatched = 0;
+ struct request *rq;
+ unsigned long service_to_charge;
+
+ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
+
+ /* Follow expired path, else get first next available. */
+ rq = bfq_check_fifo(bfqq);
+ if (!rq)
+ rq = bfqq->next_rq;
+ service_to_charge = bfq_serv_to_charge(rq, bfqq);
+
+ if (service_to_charge > bfq_bfqq_budget_left(bfqq)) {
+ /*
+ * This may happen if the next rq is chosen in fifo order
+ * instead of sector order. The budget is properly
+ * dimensioned to be always sufficient to serve the next
+ * request only if it is chosen in sector order. The reason
+ * is that it would be quite inefficient and little useful
+ * to always make sure that the budget is large enough to
+ * serve even the possible next rq in fifo order.
+ * In fact, requests are seldom served in fifo order.
+ *
+ * Expire the queue for budget exhaustion, and make sure
+ * that the next act_budget is enough to serve the next
+ * request, even if it comes from the fifo expired path.
+ */
+ bfqq->next_rq = rq;
+ /*
+ * Since this dispatch is failed, make sure that
+ * a new one will be performed
+ */
+ if (!bfqd->rq_in_driver)
+ bfq_schedule_dispatch(bfqd);
+ BUG_ON(bfqq->entity.budget < bfqq->entity.service);
+ goto expire;
+ }
+
+ BUG_ON(bfqq->entity.budget < bfqq->entity.service);
+ /* Finally, insert request into driver dispatch list. */
+ bfq_bfqq_served(bfqq, service_to_charge);
+
+ BUG_ON(bfqq->entity.budget < bfqq->entity.service);
+
+ bfq_dispatch_insert(bfqd->queue, rq);
+
+ /*
+ * If weight raising has to terminate for bfqq, then next
+ * function causes an immediate update of bfqq's weight,
+ * without waiting for next activation. As a consequence, on
+ * expiration, bfqq will be timestamped as if has never been
+ * weight-raised during this service slot, even if it has
+ * received part or even most of the service as a
+ * weight-raised queue. This inflates bfqq's timestamps, which
+ * is beneficial, as bfqq is then more willing to leave the
+ * device immediately to possible other weight-raised queues.
+ */
+ bfq_update_wr_data(bfqd, bfqq);
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "dispatched %u sec req (%llu), budg left %d",
+ blk_rq_sectors(rq),
+ (unsigned long long) blk_rq_pos(rq),
+ bfq_bfqq_budget_left(bfqq));
+
+ dispatched++;
+
+ if (!bfqd->in_service_bic) {
+ atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount);
+ bfqd->in_service_bic = RQ_BIC(rq);
+ }
+
+ if (bfqd->busy_queues > 1 && bfq_class_idle(bfqq))
+ goto expire;
+
+ return dispatched;
+
+expire:
+ bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED);
+ return dispatched;
+}
+
+static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq)
+{
+ int dispatched = 0;
+
+ while (bfqq->next_rq) {
+ bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq);
+ dispatched++;
+ }
+
+ BUG_ON(!list_empty(&bfqq->fifo));
+ return dispatched;
+}
+
+/*
+ * Drain our current requests.
+ * Used for barriers and when switching io schedulers on-the-fly.
+ */
+static int bfq_forced_dispatch(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq, *n;
+ struct bfq_service_tree *st;
+ int dispatched = 0;
+
+ bfqq = bfqd->in_service_queue;
+ if (bfqq)
+ __bfq_bfqq_expire(bfqd, bfqq);
+
+ /*
+ * Loop through classes, and be careful to leave the scheduler
+ * in a consistent state, as feedback mechanisms and vtime
+ * updates cannot be disabled during the process.
+ */
+ list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) {
+ st = bfq_entity_service_tree(&bfqq->entity);
+
+ dispatched += __bfq_forced_dispatch_bfqq(bfqq);
+
+ bfqq->max_budget = bfq_max_budget(bfqd);
+ bfq_forget_idle(st);
+ }
+
+ BUG_ON(bfqd->busy_queues != 0);
+
+ return dispatched;
+}
+
+static int bfq_dispatch_requests(struct request_queue *q, int force)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_queue *bfqq;
+
+ bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
+
+ if (bfqd->busy_queues == 0)
+ return 0;
+
+ if (unlikely(force))
+ return bfq_forced_dispatch(bfqd);
+
+ if (bfqd->strict_guarantees && bfqd->rq_in_driver > 0)
+ return 0;
+
+ bfqq = bfq_select_queue(bfqd);
+ if (!bfqq)
+ return 0;
+
+ BUG_ON(bfqq->entity.budget < bfqq->entity.service);
+
+ BUG_ON(bfq_bfqq_wait_request(bfqq));
+
+ if (!bfq_dispatch_request(bfqd, bfqq))
+ return 0;
+
+ bfq_log_bfqq(bfqd, bfqq, "dispatched %s request",
+ bfq_bfqq_sync(bfqq) ? "sync" : "async");
+
+ BUG_ON(bfqq->next_rq == NULL &&
+ bfqq->entity.budget < bfqq->entity.service);
+ return 1;
+}
+
+/*
+ * Task holds one reference to the queue, dropped when task exits. Each rq
+ * in-flight on this queue also holds a reference, dropped when rq is freed.
+ *
+ * Queue lock must be held here.
+ */
+static void bfq_put_queue(struct bfq_queue *bfqq)
+{
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ struct bfq_group *bfqg = bfqq_group(bfqq);
+#endif
+
+ BUG_ON(bfqq->ref <= 0);
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p %d", bfqq, bfqq->ref);
+ bfqq->ref--;
+ if (bfqq->ref)
+ return;
+
+ BUG_ON(rb_first(&bfqq->sort_list));
+ BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0);
+ BUG_ON(bfqq->entity.tree);
+ BUG_ON(bfq_bfqq_busy(bfqq));
+ BUG_ON(bfqq->bfqd->in_service_queue == bfqq);
+
+ if (bfq_bfqq_sync(bfqq))
+ /*
+ * The fact that this queue is being destroyed does not
+ * invalidate the fact that this queue may have been
+ * activated during the current burst. As a consequence,
+ * although the queue does not exist anymore, and hence
+ * needs to be removed from the burst list if there,
+ * the burst size has not to be decremented.
+ */
+ hlist_del_init(&bfqq->burst_list_node);
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
+
+ kmem_cache_free(bfq_pool, bfqq);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ bfqg_put(bfqg);
+#endif
+}
+
+static void bfq_put_cooperator(struct bfq_queue *bfqq)
+{
+ struct bfq_queue *__bfqq, *next;
+
+ /*
+ * If this queue was scheduled to merge with another queue, be
+ * sure to drop the reference taken on that queue (and others in
+ * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs.
+ */
+ __bfqq = bfqq->new_bfqq;
+ while (__bfqq) {
+ if (__bfqq == bfqq)
+ break;
+ next = __bfqq->new_bfqq;
+ bfq_put_queue(__bfqq);
+ __bfqq = next;
+ }
+}
+
+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ if (bfqq == bfqd->in_service_queue) {
+ __bfq_bfqq_expire(bfqd, bfqq);
+ bfq_schedule_dispatch(bfqd);
+ }
+
+ bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, bfqq->ref);
+
+ bfq_put_cooperator(bfqq);
+
+ bfq_put_queue(bfqq);
+}
+
+static void bfq_init_icq(struct io_cq *icq)
+{
+ icq_to_bic(icq)->ttime.last_end_request = ktime_get_ns() - (1ULL<<32);
+}
+
+static void bfq_exit_icq(struct io_cq *icq)
+{
+ struct bfq_io_cq *bic = icq_to_bic(icq);
+ struct bfq_data *bfqd = bic_to_bfqd(bic);
+
+ if (bic_to_bfqq(bic, false)) {
+ bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, false));
+ bic_set_bfqq(bic, NULL, false);
+ }
+
+ if (bic_to_bfqq(bic, true)) {
+ /*
+ * If the bic is using a shared queue, put the reference
+ * taken on the io_context when the bic started using a
+ * shared bfq_queue.
+ */
+ if (bfq_bfqq_coop(bic_to_bfqq(bic, true)))
+ put_io_context(icq->ioc);
+ bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, true));
+ bic_set_bfqq(bic, NULL, true);
+ }
+}
+
+/*
+ * Update the entity prio values; note that the new values will not
+ * be used until the next (re)activation.
+ */
+static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
+ struct bfq_io_cq *bic)
+{
+ struct task_struct *tsk = current;
+ int ioprio_class;
+
+ ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
+ switch (ioprio_class) {
+ default:
+ dev_err(bfqq->bfqd->queue->backing_dev_info.dev,
+ "bfq: bad prio class %d\n", ioprio_class);
+ case IOPRIO_CLASS_NONE:
+ /*
+ * No prio set, inherit CPU scheduling settings.
+ */
+ bfqq->new_ioprio = task_nice_ioprio(tsk);
+ bfqq->new_ioprio_class = task_nice_ioclass(tsk);
+ break;
+ case IOPRIO_CLASS_RT:
+ bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
+ bfqq->new_ioprio_class = IOPRIO_CLASS_RT;
+ break;
+ case IOPRIO_CLASS_BE:
+ bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
+ bfqq->new_ioprio_class = IOPRIO_CLASS_BE;
+ break;
+ case IOPRIO_CLASS_IDLE:
+ bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE;
+ bfqq->new_ioprio = 7;
+ bfq_clear_bfqq_idle_window(bfqq);
+ break;
+ }
+
+ if (bfqq->new_ioprio >= IOPRIO_BE_NR) {
+ pr_crit("bfq_set_next_ioprio_data: new_ioprio %d\n",
+ bfqq->new_ioprio);
+ BUG();
+ }
+
+ bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
+ bfqq->entity.prio_changed = 1;
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "set_next_ioprio_data: bic_class %d prio %d class %d",
+ ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class);
+}
+
+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
+{
+ struct bfq_data *bfqd = bic_to_bfqd(bic);
+ struct bfq_queue *bfqq;
+ unsigned long uninitialized_var(flags);
+ int ioprio = bic->icq.ioc->ioprio;
+
+ /*
+ * This condition may trigger on a newly created bic, be sure to
+ * drop the lock before returning.
+ */
+ if (unlikely(!bfqd) || likely(bic->ioprio == ioprio))
+ return;
+
+ bic->ioprio = ioprio;
+
+ bfqq = bic_to_bfqq(bic, false);
+ if (bfqq) {
+ bfq_put_queue(bfqq);
+ bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic);
+ bic_set_bfqq(bic, bfqq, false);
+ bfq_log_bfqq(bfqd, bfqq,
+ "check_ioprio_change: bfqq %p %d",
+ bfqq, bfqq->ref);
+ }
+
+ bfqq = bic_to_bfqq(bic, true);
+ if (bfqq)
+ bfq_set_next_ioprio_data(bfqq, bic);
+}
+
+static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct bfq_io_cq *bic, pid_t pid, int is_sync)
+{
+ RB_CLEAR_NODE(&bfqq->entity.rb_node);
+ INIT_LIST_HEAD(&bfqq->fifo);
+ INIT_HLIST_NODE(&bfqq->burst_list_node);
+ BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
+
+ bfqq->ref = 0;
+ bfqq->bfqd = bfqd;
+
+ if (bic)
+ bfq_set_next_ioprio_data(bfqq, bic);
+
+ if (is_sync) {
+ if (!bfq_class_idle(bfqq))
+ bfq_mark_bfqq_idle_window(bfqq);
+ bfq_mark_bfqq_sync(bfqq);
+ bfq_mark_bfqq_just_created(bfqq);
+ } else
+ bfq_clear_bfqq_sync(bfqq);
+ bfq_mark_bfqq_IO_bound(bfqq);
+
+ /* Tentative initial value to trade off between thr and lat */
+ bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3;
+ bfqq->pid = pid;
+
+ bfqq->wr_coeff = 1;
+ bfqq->last_wr_start_finish = bfq_smallest_from_now();
+ bfqq->budget_timeout = bfq_smallest_from_now();
+ bfqq->split_time = bfq_smallest_from_now();
+ /*
+ * Set to the value for which bfqq will not be deemed as
+ * soft rt when it becomes backlogged.
+ */
+ bfqq->soft_rt_next_start = bfq_greatest_from_now();
+
+ /* first request is almost certainly seeky */
+ bfqq->seek_history = 1;
+}
+
+static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ int ioprio_class, int ioprio)
+{
+ switch (ioprio_class) {
+ case IOPRIO_CLASS_RT:
+ return &bfqg->async_bfqq[0][ioprio];
+ case IOPRIO_CLASS_NONE:
+ ioprio = IOPRIO_NORM;
+ /* fall through */
+ case IOPRIO_CLASS_BE:
+ return &bfqg->async_bfqq[1][ioprio];
+ case IOPRIO_CLASS_IDLE:
+ return &bfqg->async_idle_bfqq;
+ default:
+ BUG();
+ }
+}
+
+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
+ struct bio *bio, bool is_sync,
+ struct bfq_io_cq *bic)
+{
+ const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
+ const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
+ struct bfq_queue **async_bfqq = NULL;
+ struct bfq_queue *bfqq;
+ struct bfq_group *bfqg;
+
+ rcu_read_lock();
+
+ bfqg = bfq_find_set_group(bfqd, bio_blkcg(bio));
+ if (!bfqg) {
+ bfqq = &bfqd->oom_bfqq;
+ goto out;
+ }
+
+ if (!is_sync) {
+ async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
+ ioprio);
+ bfqq = *async_bfqq;
+ if (bfqq)
+ goto out;
+ }
+
+ bfqq = kmem_cache_alloc_node(bfq_pool, GFP_NOWAIT | __GFP_ZERO,
+ bfqd->queue->node);
+
+ if (bfqq) {
+ bfq_init_bfqq(bfqd, bfqq, bic, current->pid,
+ is_sync);
+ bfq_init_entity(&bfqq->entity, bfqg);
+ bfq_log_bfqq(bfqd, bfqq, "allocated");
+ } else {
+ bfqq = &bfqd->oom_bfqq;
+ bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
+ goto out;
+ }
+
+ /*
+ * Pin the queue now that it's allocated, scheduler exit will
+ * prune it.
+ */
+ if (async_bfqq) {
+ bfqq->ref++;
+ bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
+ bfqq, bfqq->ref);
+ *async_bfqq = bfqq;
+ }
+
+out:
+ bfqq->ref++;
+ bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, bfqq->ref);
+ rcu_read_unlock();
+ return bfqq;
+}
+
+static void bfq_update_io_thinktime(struct bfq_data *bfqd,
+ struct bfq_io_cq *bic)
+{
+ struct bfq_ttime *ttime = &bic->ttime;
+ u64 elapsed = ktime_get_ns() - bic->ttime.last_end_request;
+
+ elapsed = min(elapsed, 2UL * bfqd->bfq_slice_idle);
+
+ ttime->ttime_samples = (7*bic->ttime.ttime_samples + 256) / 8;
+ ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed, 8);
+ ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
+ ttime->ttime_samples);
+}
+
+static void
+bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct request *rq)
+{
+ bfqq->seek_history <<= 1;
+ bfqq->seek_history |=
+ get_sdist(bfqq->last_request_pos, rq) > BFQQ_SEEK_THR;
+}
+
+/*
+ * Disable idle window if the process thinks too long or seeks so much that
+ * it doesn't matter.
+ */
+static void bfq_update_idle_window(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct bfq_io_cq *bic)
+{
+ int enable_idle;
+
+ /* Don't idle for async or idle io prio class. */
+ if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq))
+ return;
+
+ /* Idle window just restored, statistics are meaningless. */
+ if (time_is_after_eq_jiffies(bfqq->split_time +
+ bfqd->bfq_wr_min_idle_time))
+ return;
+
+ enable_idle = bfq_bfqq_idle_window(bfqq);
+
+ if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
+ bfqd->bfq_slice_idle == 0 ||
+ (bfqd->hw_tag && BFQQ_SEEKY(bfqq) &&
+ bfqq->wr_coeff == 1))
+ enable_idle = 0;
+ else if (bfq_sample_valid(bic->ttime.ttime_samples)) {
+ if (bic->ttime.ttime_mean > bfqd->bfq_slice_idle &&
+ bfqq->wr_coeff == 1)
+ enable_idle = 0;
+ else
+ enable_idle = 1;
+ }
+ bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d",
+ enable_idle);
+
+ if (enable_idle)
+ bfq_mark_bfqq_idle_window(bfqq);
+ else
+ bfq_clear_bfqq_idle_window(bfqq);
+}
+
+/*
+ * Called when a new fs request (rq) is added to bfqq. Check if there's
+ * something we should do about it.
+ */
+static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct request *rq)
+{
+ struct bfq_io_cq *bic = RQ_BIC(rq);
+
+ if (rq->cmd_flags & REQ_META)
+ bfqq->meta_pending++;
+
+ bfq_update_io_thinktime(bfqd, bic);
+ bfq_update_io_seektime(bfqd, bfqq, rq);
+ if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 ||
+ !BFQQ_SEEKY(bfqq))
+ bfq_update_idle_window(bfqd, bfqq, bic);
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "rq_enqueued: idle_window=%d (seeky %d)",
+ bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq));
+
+ bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
+
+ if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) {
+ bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 &&
+ blk_rq_sectors(rq) < 32;
+ bool budget_timeout = bfq_bfqq_budget_timeout(bfqq);
+
+ /*
+ * There is just this request queued: if the request
+ * is small and the queue is not to be expired, then
+ * just exit.
+ *
+ * In this way, if the device is being idled to wait
+ * for a new request from the in-service queue, we
+ * avoid unplugging the device and committing the
+ * device to serve just a small request. On the
+ * contrary, we wait for the block layer to decide
+ * when to unplug the device: hopefully, new requests
+ * will be merged to this one quickly, then the device
+ * will be unplugged and larger requests will be
+ * dispatched.
+ */
+ if (small_req && !budget_timeout)
+ return;
+
+ /*
+ * A large enough request arrived, or the queue is to
+ * be expired: in both cases disk idling is to be
+ * stopped, so clear wait_request flag and reset
+ * timer.
+ */
+ bfq_clear_bfqq_wait_request(bfqq);
+ hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
+ bfqg_stats_update_idle_time(bfqq_group(bfqq));
+
+ /*
+ * The queue is not empty, because a new request just
+ * arrived. Hence we can safely expire the queue, in
+ * case of budget timeout, without risking that the
+ * timestamps of the queue are not updated correctly.
+ * See [1] for more details.
+ */
+ if (budget_timeout)
+ bfq_bfqq_expire(bfqd, bfqq, false,
+ BFQ_BFQQ_BUDGET_TIMEOUT);
+
+ /*
+ * Let the request rip immediately, or let a new queue be
+ * selected if bfqq has just been expired.
+ */
+ __blk_run_queue(bfqd->queue);
+ }
+}
+
+static void bfq_insert_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
+
+ assert_spin_locked(bfqd->queue->queue_lock);
+
+ /*
+ * An unplug may trigger a requeue of a request from the device
+ * driver: make sure we are in process context while trying to
+ * merge two bfq_queues.
+ */
+ if (!in_interrupt()) {
+ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true);
+ if (new_bfqq) {
+ if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq)
+ new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1);
+ /*
+ * Release the request's reference to the old bfqq
+ * and make sure one is taken to the shared queue.
+ */
+ new_bfqq->allocated[rq_data_dir(rq)]++;
+ bfqq->allocated[rq_data_dir(rq)]--;
+ new_bfqq->ref++;
+ bfq_clear_bfqq_just_created(bfqq);
+ bfq_put_queue(bfqq);
+ if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
+ bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
+ bfqq, new_bfqq);
+ rq->elv.priv[1] = new_bfqq;
+ bfqq = new_bfqq;
+ }
+ }
+
+ bfq_add_request(rq);
+
+ rq->fifo_time = ktime_get_ns() +
+ jiffies_to_nsecs(bfqd->bfq_fifo_expire[rq_is_sync(rq)]);
+ list_add_tail(&rq->queuelist, &bfqq->fifo);
+
+ bfq_rq_enqueued(bfqd, bfqq, rq);
+}
+
+static void bfq_update_hw_tag(struct bfq_data *bfqd)
+{
+ bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver,
+ bfqd->rq_in_driver);
+
+ if (bfqd->hw_tag == 1)
+ return;
+
+ /*
+ * This sample is valid if the number of outstanding requests
+ * is large enough to allow a queueing behavior. Note that the
+ * sum is not exact, as it's not taking into account deactivated
+ * requests.
+ */
+ if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD)
+ return;
+
+ if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)
+ return;
+
+ bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD;
+ bfqd->max_rq_in_driver = 0;
+ bfqd->hw_tag_samples = 0;
+}
+
+static void bfq_completed_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ ktime_t now;
+
+ bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left",
+ blk_rq_sectors(rq));
+
+ assert_spin_locked(bfqd->queue->queue_lock);
+ bfq_update_hw_tag(bfqd);
+
+ BUG_ON(!bfqd->rq_in_driver);
+ BUG_ON(!bfqq->dispatched);
+ bfqd->rq_in_driver--;
+ bfqq->dispatched--;
+ bfqg_stats_update_completion(bfqq_group(bfqq),
+ rq_start_time_ns(rq),
+ rq_io_start_time_ns(rq), req_op(rq),
+ rq->cmd_flags);
+
+ if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
+ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
+ /*
+ * Set budget_timeout (which we overload to store the
+ * time at which the queue remains with no backlog and
+ * no outstanding request; used by the weight-raising
+ * mechanism).
+ */
+ bfqq->budget_timeout = jiffies;
+
+ bfq_weights_tree_remove(bfqd, &bfqq->entity,
+ &bfqd->queue_weights_tree);
+ }
+
+ now = ktime_get();
+
+ RQ_BIC(rq)->ttime.last_end_request = ktime_to_ns(now);
+
+ if (bfqd->rq_in_driver == 0)
+ bfqd->last_completion = ktime_to_us(now);
+
+ /*
+ * If we are waiting to discover whether the request pattern
+ * of the task associated with the queue is actually
+ * isochronous, and both requisites for this condition to hold
+ * are now satisfied, then compute soft_rt_next_start (see the
+ * comments on the function bfq_bfqq_softrt_next_start()). We
+ * schedule this delayed check when bfqq expires, if it still
+ * has in-flight requests.
+ */
+ if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 &&
+ RB_EMPTY_ROOT(&bfqq->sort_list))
+ bfqq->soft_rt_next_start =
+ bfq_bfqq_softrt_next_start(bfqd, bfqq);
+
+ /*
+ * If this is the in-service queue, check if it needs to be expired,
+ * or if we want to idle in case it has no pending requests.
+ */
+ if (bfqd->in_service_queue == bfqq) {
+ if (bfqq->dispatched == 0 && bfq_bfqq_must_idle(bfqq)) {
+ bfq_arm_slice_timer(bfqd);
+ goto out;
+ } else if (bfq_may_expire_for_budg_timeout(bfqq))
+ bfq_bfqq_expire(bfqd, bfqq, false,
+ BFQ_BFQQ_BUDGET_TIMEOUT);
+ else if (RB_EMPTY_ROOT(&bfqq->sort_list) &&
+ (bfqq->dispatched == 0 ||
+ !bfq_bfqq_may_idle(bfqq)))
+ bfq_bfqq_expire(bfqd, bfqq, false,
+ BFQ_BFQQ_NO_MORE_REQUESTS);
+ }
+
+ if (!bfqd->rq_in_driver)
+ bfq_schedule_dispatch(bfqd);
+
+out:
+ return;
+}
+
+static int __bfq_may_queue(struct bfq_queue *bfqq)
+{
+ if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) {
+ bfq_clear_bfqq_must_alloc(bfqq);
+ return ELV_MQUEUE_MUST;
+ }
+
+ return ELV_MQUEUE_MAY;
+}
+
+static int bfq_may_queue(struct request_queue *q, int op, int op_flags)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct task_struct *tsk = current;
+ struct bfq_io_cq *bic;
+ struct bfq_queue *bfqq;
+
+ /*
+ * Don't force setup of a queue from here, as a call to may_queue
+ * does not necessarily imply that a request actually will be
+ * queued. So just lookup a possibly existing queue, or return
+ * 'may queue' if that fails.
+ */
+ bic = bfq_bic_lookup(bfqd, tsk->io_context);
+ if (!bic)
+ return ELV_MQUEUE_MAY;
+
+ bfqq = bic_to_bfqq(bic, rw_is_sync(op, op_flags));
+ if (bfqq)
+ return __bfq_may_queue(bfqq);
+
+ return ELV_MQUEUE_MAY;
+}
+
+/*
+ * Queue lock held here.
+ */
+static void bfq_put_request(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ if (bfqq) {
+ const int rw = rq_data_dir(rq);
+
+ BUG_ON(!bfqq->allocated[rw]);
+ bfqq->allocated[rw]--;
+
+ rq->elv.priv[0] = NULL;
+ rq->elv.priv[1] = NULL;
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d",
+ bfqq, bfqq->ref);
+ bfq_put_queue(bfqq);
+ }
+}
+
+/*
+ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this
+ * was the last process referring to that bfqq.
+ */
+static struct bfq_queue *
+bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
+{
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue");
+
+ put_io_context(bic->icq.ioc);
+
+ if (bfqq_process_refs(bfqq) == 1) {
+ bfqq->pid = current->pid;
+ bfq_clear_bfqq_coop(bfqq);
+ bfq_clear_bfqq_split_coop(bfqq);
+ return bfqq;
+ }
+
+ bic_set_bfqq(bic, NULL, 1);
+
+ bfq_put_cooperator(bfqq);
+
+ bfq_put_queue(bfqq);
+ return NULL;
+}
+
+/*
+ * Allocate bfq data structures associated with this request.
+ */
+static int bfq_set_request(struct request_queue *q, struct request *rq,
+ struct bio *bio, gfp_t gfp_mask)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq);
+ const int rw = rq_data_dir(rq);
+ const int is_sync = rq_is_sync(rq);
+ struct bfq_queue *bfqq;
+ unsigned long flags;
+ bool split = false;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ bfq_check_ioprio_change(bic, bio);
+
+ if (!bic)
+ goto queue_fail;
+
+ bfq_bic_update_cgroup(bic, bio);
+
+new_queue:
+ bfqq = bic_to_bfqq(bic, is_sync);
+ if (!bfqq || bfqq == &bfqd->oom_bfqq) {
+ if (bfqq)
+ bfq_put_queue(bfqq);
+ bfqq = bfq_get_queue(bfqd, bio, is_sync, bic);
+ BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
+
+ bic_set_bfqq(bic, bfqq, is_sync);
+ if (split && is_sync) {
+ bfq_log_bfqq(bfqd, bfqq,
+ "set_request: was_in_list %d "
+ "was_in_large_burst %d "
+ "large burst in progress %d",
+ bic->was_in_burst_list,
+ bic->saved_in_large_burst,
+ bfqd->large_burst);
+
+ if ((bic->was_in_burst_list && bfqd->large_burst) ||
+ bic->saved_in_large_burst) {
+ bfq_log_bfqq(bfqd, bfqq,
+ "set_request: marking in "
+ "large burst");
+ bfq_mark_bfqq_in_large_burst(bfqq);
+ } else {
+ bfq_log_bfqq(bfqd, bfqq,
+ "set_request: clearing in "
+ "large burst");
+ bfq_clear_bfqq_in_large_burst(bfqq);
+ if (bic->was_in_burst_list)
+ hlist_add_head(&bfqq->burst_list_node,
+ &bfqd->burst_list);
+ }
+ bfqq->split_time = jiffies;
+ }
+ } else {
+ /* If the queue was seeky for too long, break it apart. */
+ if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
+ bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
+
+ /* Update bic before losing reference to bfqq */
+ if (bfq_bfqq_in_large_burst(bfqq))
+ bic->saved_in_large_burst = true;
+
+ bfqq = bfq_split_bfqq(bic, bfqq);
+ split = true;
+ if (!bfqq)
+ goto new_queue;
+ }
+ }
+
+ bfqq->allocated[rw]++;
+ bfqq->ref++;
+ bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, bfqq->ref);
+
+ rq->elv.priv[0] = bic;
+ rq->elv.priv[1] = bfqq;
+
+ /*
+ * If a bfq_queue has only one process reference, it is owned
+ * by only one bfq_io_cq: we can set the bic field of the
+ * bfq_queue to the address of that structure. Also, if the
+ * queue has just been split, mark a flag so that the
+ * information is available to the other scheduler hooks.
+ */
+ if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
+ bfqq->bic = bic;
+ if (split) {
+ /*
+ * If the queue has just been split from a shared
+ * queue, restore the idle window and the possible
+ * weight raising period.
+ */
+ bfq_bfqq_resume_state(bfqq, bic);
+ }
+ }
+
+ if (unlikely(bfq_bfqq_just_created(bfqq)))
+ bfq_handle_burst(bfqd, bfqq);
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return 0;
+
+queue_fail:
+ bfq_schedule_dispatch(bfqd);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return 1;
+}
+
+static void bfq_kick_queue(struct work_struct *work)
+{
+ struct bfq_data *bfqd =
+ container_of(work, struct bfq_data, unplug_work);
+ struct request_queue *q = bfqd->queue;
+
+ spin_lock_irq(q->queue_lock);
+ __blk_run_queue(q);
+ spin_unlock_irq(q->queue_lock);
+}
+
+/*
+ * Handler of the expiration of the timer running if the in-service queue
+ * is idling inside its time slice.
+ */
+static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer)
+{
+ struct bfq_data *bfqd = container_of(timer, struct bfq_data,
+ idle_slice_timer);
+ struct bfq_queue *bfqq;
+ unsigned long flags;
+ enum bfqq_expiration reason;
+
+ spin_lock_irqsave(bfqd->queue->queue_lock, flags);
+
+ bfqq = bfqd->in_service_queue;
+ /*
+ * Theoretical race here: the in-service queue can be NULL or
+ * different from the queue that was idling if the timer handler
+ * spins on the queue_lock and a new request arrives for the
+ * current queue and there is a full dispatch cycle that changes
+ * the in-service queue. This can hardly happen, but in the worst
+ * case we just expire a queue too early.
+ */
+ if (bfqq) {
+ bfq_log_bfqq(bfqd, bfqq, "slice_timer expired");
+ bfq_clear_bfqq_wait_request(bfqq);
+
+ if (bfq_bfqq_budget_timeout(bfqq))
+ /*
+ * Also here the queue can be safely expired
+ * for budget timeout without wasting
+ * guarantees
+ */
+ reason = BFQ_BFQQ_BUDGET_TIMEOUT;
+ else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
+ /*
+ * The queue may not be empty upon timer expiration,
+ * because we may not disable the timer when the
+ * first request of the in-service queue arrives
+ * during disk idling.
+ */
+ reason = BFQ_BFQQ_TOO_IDLE;
+ else
+ goto schedule_dispatch;
+
+ bfq_bfqq_expire(bfqd, bfqq, true, reason);
+ }
+
+schedule_dispatch:
+ bfq_schedule_dispatch(bfqd);
+
+ spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
+ return HRTIMER_NORESTART;
+}
+
+static void bfq_shutdown_timer_wq(struct bfq_data *bfqd)
+{
+ hrtimer_cancel(&bfqd->idle_slice_timer);
+ cancel_work_sync(&bfqd->unplug_work);
+}
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
+ struct bfq_queue **bfqq_ptr)
+{
+ struct bfq_group *root_group = bfqd->root_group;
+ struct bfq_queue *bfqq = *bfqq_ptr;
+
+ bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
+ if (bfqq) {
+ bfq_bfqq_move(bfqd, bfqq, root_group);
+ bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
+ bfqq, bfqq->ref);
+ bfq_put_queue(bfqq);
+ *bfqq_ptr = NULL;
+ }
+}
+
+/*
+ * Release all the bfqg references to its async queues. If we are
+ * deallocating the group these queues may still contain requests, so
+ * we reparent them to the root cgroup (i.e., the only one that will
+ * exist for sure until all the requests on a device are gone).
+ */
+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
+{
+ int i, j;
+
+ for (i = 0; i < 2; i++)
+ for (j = 0; j < IOPRIO_BE_NR; j++)
+ __bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
+
+ __bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
+}
+#endif
+
+static void bfq_exit_queue(struct elevator_queue *e)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ struct request_queue *q = bfqd->queue;
+ struct bfq_queue *bfqq, *n;
+
+ bfq_shutdown_timer_wq(bfqd);
+
+ spin_lock_irq(q->queue_lock);
+
+ BUG_ON(bfqd->in_service_queue);
+ list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
+ bfq_deactivate_bfqq(bfqd, bfqq, 0);
+
+ spin_unlock_irq(q->queue_lock);
+
+ bfq_shutdown_timer_wq(bfqd);
+
+ BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ blkcg_deactivate_policy(q, &blkcg_policy_bfq);
+#else
+ kfree(bfqd->root_group);
+#endif
+
+ kfree(bfqd);
+}
+
+static void bfq_init_root_group(struct bfq_group *root_group,
+ struct bfq_data *bfqd)
+{
+ int i;
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ root_group->entity.parent = NULL;
+ root_group->my_entity = NULL;
+ root_group->bfqd = bfqd;
+#endif
+ root_group->rq_pos_tree = RB_ROOT;
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+ root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
+}
+
+static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
+{
+ struct bfq_data *bfqd;
+ struct elevator_queue *eq;
+
+ eq = elevator_alloc(q, e);
+ if (!eq)
+ return -ENOMEM;
+
+ bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node);
+ if (!bfqd) {
+ kobject_put(&eq->kobj);
+ return -ENOMEM;
+ }
+ eq->elevator_data = bfqd;
+
+ /*
+ * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues.
+ * Grab a permanent reference to it, so that the normal code flow
+ * will not attempt to free it.
+ */
+ bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0);
+ bfqd->oom_bfqq.ref++;
+ bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO;
+ bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE;
+ bfqd->oom_bfqq.entity.new_weight =
+ bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio);
+
+ /* oom_bfqq does not participate to bursts */
+ bfq_clear_bfqq_just_created(&bfqd->oom_bfqq);
+ /*
+ * Trigger weight initialization, according to ioprio, at the
+ * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio
+ * class won't be changed any more.
+ */
+ bfqd->oom_bfqq.entity.prio_changed = 1;
+
+ bfqd->queue = q;
+
+ spin_lock_irq(q->queue_lock);
+ q->elevator = eq;
+ spin_unlock_irq(q->queue_lock);
+
+ bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node);
+ if (!bfqd->root_group)
+ goto out_free;
+ bfq_init_root_group(bfqd->root_group, bfqd);
+ bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
+
+ hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC,
+ HRTIMER_MODE_REL);
+ bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
+
+ bfqd->queue_weights_tree = RB_ROOT;
+ bfqd->group_weights_tree = RB_ROOT;
+
+ INIT_WORK(&bfqd->unplug_work, bfq_kick_queue);
+
+ INIT_LIST_HEAD(&bfqd->active_list);
+ INIT_LIST_HEAD(&bfqd->idle_list);
+ INIT_HLIST_HEAD(&bfqd->burst_list);
+
+ bfqd->hw_tag = -1;
+
+ bfqd->bfq_max_budget = bfq_default_max_budget;
+
+ bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0];
+ bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1];
+ bfqd->bfq_back_max = bfq_back_max;
+ bfqd->bfq_back_penalty = bfq_back_penalty;
+ bfqd->bfq_slice_idle = bfq_slice_idle;
+ bfqd->bfq_class_idle_last_service = 0;
+ bfqd->bfq_timeout = bfq_timeout;
+
+ bfqd->bfq_requests_within_timer = 120;
+
+ bfqd->bfq_large_burst_thresh = 8;
+ bfqd->bfq_burst_interval = msecs_to_jiffies(180);
+
+ bfqd->low_latency = true;
+
+ /*
+ * Trade-off between responsiveness and fairness.
+ */
+ bfqd->bfq_wr_coeff = 30;
+ bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300);
+ bfqd->bfq_wr_max_time = 0;
+ bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000);
+ bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500);
+ bfqd->bfq_wr_max_softrt_rate = 7000; /*
+ * Approximate rate required
+ * to playback or record a
+ * high-definition compressed
+ * video.
+ */
+ bfqd->wr_busy_queues = 0;
+
+ /*
+ * Begin by assuming, optimistically, that the device is a
+ * high-speed one, and that its peak rate is equal to 2/3 of
+ * the highest reference rate.
+ */
+ bfqd->RT_prod = R_fast[blk_queue_nonrot(bfqd->queue)] *
+ T_fast[blk_queue_nonrot(bfqd->queue)];
+ bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)] * 2 / 3;
+ bfqd->device_speed = BFQ_BFQD_FAST;
+
+ return 0;
+
+out_free:
+ kfree(bfqd);
+ kobject_put(&eq->kobj);
+ return -ENOMEM;
+}
+
+static void bfq_slab_kill(void)
+{
+ kmem_cache_destroy(bfq_pool);
+}
+
+static int __init bfq_slab_setup(void)
+{
+ bfq_pool = KMEM_CACHE(bfq_queue, 0);
+ if (!bfq_pool)
+ return -ENOMEM;
+ return 0;
+}
+
+static ssize_t bfq_var_show(unsigned int var, char *page)
+{
+ return sprintf(page, "%u\n", var);
+}
+
+static ssize_t bfq_var_store(unsigned long *var, const char *page,
+ size_t count)
+{
+ unsigned long new_val;
+ int ret = kstrtoul(page, 10, &new_val);
+
+ if (ret == 0)
+ *var = new_val;
+
+ return count;
+}
+
+static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+
+ return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ?
+ jiffies_to_msecs(bfqd->bfq_wr_max_time) :
+ jiffies_to_msecs(bfq_wr_duration(bfqd)));
+}
+
+static ssize_t bfq_weights_show(struct elevator_queue *e, char *page)
+{
+ struct bfq_queue *bfqq;
+ struct bfq_data *bfqd = e->elevator_data;
+ ssize_t num_char = 0;
+
+ num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n",
+ bfqd->queued);
+
+ spin_lock_irq(bfqd->queue->queue_lock);
+
+ num_char += sprintf(page + num_char, "Active:\n");
+ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) {
+ num_char += sprintf(page + num_char,
+ "pid%d: weight %hu, nr_queued %d %d, ",
+ bfqq->pid,
+ bfqq->entity.weight,
+ bfqq->queued[0],
+ bfqq->queued[1]);
+ num_char += sprintf(page + num_char,
+ "dur %d/%u\n",
+ jiffies_to_msecs(
+ jiffies -
+ bfqq->last_wr_start_finish),
+ jiffies_to_msecs(bfqq->wr_cur_max_time));
+ }
+
+ num_char += sprintf(page + num_char, "Idle:\n");
+ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) {
+ num_char += sprintf(page + num_char,
+ "pid%d: weight %hu, dur %d/%u\n",
+ bfqq->pid,
+ bfqq->entity.weight,
+ jiffies_to_msecs(jiffies -
+ bfqq->last_wr_start_finish),
+ jiffies_to_msecs(bfqq->wr_cur_max_time));
+ }
+
+ spin_unlock_irq(bfqd->queue->queue_lock);
+
+ return num_char;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ u64 __data = __VAR; \
+ if (__CONV == 1) \
+ __data = jiffies_to_msecs(__data); \
+ else if (__CONV == 2) \
+ __data = div_u64(__data, NSEC_PER_MSEC); \
+ return bfq_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 2);
+SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 2);
+SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
+SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
+SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 2);
+SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
+SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1);
+SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0);
+SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
+SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0);
+SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1);
+SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1);
+SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async,
+ 1);
+SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0);
+#undef SHOW_FUNCTION
+
+#define USEC_SHOW_FUNCTION(__FUNC, __VAR) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ u64 __data = __VAR; \
+ __data = div_u64(__data, NSEC_PER_USEC); \
+ return bfq_var_show(__data, (page)); \
+}
+USEC_SHOW_FUNCTION(bfq_slice_idle_us_show, bfqd->bfq_slice_idle);
+#undef USEC_SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t \
+__FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ unsigned long uninitialized_var(__data); \
+ int ret = bfq_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ if (__CONV == 1) \
+ *(__PTR) = msecs_to_jiffies(__data); \
+ else if (__CONV == 2) \
+ *(__PTR) = (u64)__data * NSEC_PER_MSEC; \
+ else \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1,
+ INT_MAX, 2);
+STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1,
+ INT_MAX, 2);
+STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
+STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
+ INT_MAX, 0);
+STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2);
+STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0);
+STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1);
+STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX,
+ 1);
+STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_wr_min_inter_arr_async_store,
+ &bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1);
+STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0,
+ INT_MAX, 0);
+#undef STORE_FUNCTION
+
+#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \
+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ unsigned long __data; \
+ int ret = bfq_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ *(__PTR) = (u64)__data * NSEC_PER_USEC; \
+ return ret; \
+}
+USEC_STORE_FUNCTION(bfq_slice_idle_us_store, &bfqd->bfq_slice_idle, 0,
+ UINT_MAX);
+#undef USEC_STORE_FUNCTION
+
+/* do nothing for the moment */
+static ssize_t bfq_weights_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ return count;
+}
+
+static unsigned long bfq_estimated_max_budget(struct bfq_data *bfqd)
+{
+ if (bfqd->peak_rate_samples >= BFQ_PEAK_RATE_SAMPLES)
+ return bfq_calc_max_budget(bfqd);
+ else
+ return bfq_default_max_budget;
+}
+
+static ssize_t bfq_max_budget_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long uninitialized_var(__data);
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data == 0)
+ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd);
+ else {
+ if (__data > INT_MAX)
+ __data = INT_MAX;
+ bfqd->bfq_max_budget = __data;
+ }
+
+ bfqd->bfq_user_max_budget = __data;
+
+ return ret;
+}
+
+/*
+ * Leaving this name to preserve name compatibility with cfq
+ * parameters, but this timeout is used for both sync and async.
+ */
+static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long uninitialized_var(__data);
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data < 1)
+ __data = 1;
+ else if (__data > INT_MAX)
+ __data = INT_MAX;
+
+ bfqd->bfq_timeout = msecs_to_jiffies(__data);
+ if (bfqd->bfq_user_max_budget == 0)
+ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd);
+
+ return ret;
+}
+
+static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long uninitialized_var(__data);
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data > 1)
+ __data = 1;
+ if (!bfqd->strict_guarantees && __data == 1
+ && bfqd->bfq_slice_idle < msecs_to_jiffies(8))
+ bfqd->bfq_slice_idle = msecs_to_jiffies(8);
+
+ bfqd->strict_guarantees = __data;
+
+ return ret;
+}
+
+static ssize_t bfq_low_latency_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long uninitialized_var(__data);
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data > 1)
+ __data = 1;
+ if (__data == 0 && bfqd->low_latency != 0)
+ bfq_end_wr(bfqd);
+ bfqd->low_latency = __data;
+
+ return ret;
+}
+
+#define BFQ_ATTR(name) \
+ __ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store)
+
+static struct elv_fs_entry bfq_attrs[] = {
+ BFQ_ATTR(fifo_expire_sync),
+ BFQ_ATTR(fifo_expire_async),
+ BFQ_ATTR(back_seek_max),
+ BFQ_ATTR(back_seek_penalty),
+ BFQ_ATTR(slice_idle),
+ BFQ_ATTR(slice_idle_us),
+ BFQ_ATTR(max_budget),
+ BFQ_ATTR(timeout_sync),
+ BFQ_ATTR(strict_guarantees),
+ BFQ_ATTR(low_latency),
+ BFQ_ATTR(wr_coeff),
+ BFQ_ATTR(wr_max_time),
+ BFQ_ATTR(wr_rt_max_time),
+ BFQ_ATTR(wr_min_idle_time),
+ BFQ_ATTR(wr_min_inter_arr_async),
+ BFQ_ATTR(wr_max_softrt_rate),
+ BFQ_ATTR(weights),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_bfq = {
+ .ops = {
+ .elevator_merge_fn = bfq_merge,
+ .elevator_merged_fn = bfq_merged_request,
+ .elevator_merge_req_fn = bfq_merged_requests,
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ .elevator_bio_merged_fn = bfq_bio_merged,
+#endif
+ .elevator_allow_bio_merge_fn = bfq_allow_bio_merge,
+ .elevator_allow_rq_merge_fn = bfq_allow_rq_merge,
+ .elevator_dispatch_fn = bfq_dispatch_requests,
+ .elevator_add_req_fn = bfq_insert_request,
+ .elevator_activate_req_fn = bfq_activate_request,
+ .elevator_deactivate_req_fn = bfq_deactivate_request,
+ .elevator_completed_req_fn = bfq_completed_request,
+ .elevator_former_req_fn = elv_rb_former_request,
+ .elevator_latter_req_fn = elv_rb_latter_request,
+ .elevator_init_icq_fn = bfq_init_icq,
+ .elevator_exit_icq_fn = bfq_exit_icq,
+ .elevator_set_req_fn = bfq_set_request,
+ .elevator_put_req_fn = bfq_put_request,
+ .elevator_may_queue_fn = bfq_may_queue,
+ .elevator_init_fn = bfq_init_queue,
+ .elevator_exit_fn = bfq_exit_queue,
+ },
+ .icq_size = sizeof(struct bfq_io_cq),
+ .icq_align = __alignof__(struct bfq_io_cq),
+ .elevator_attrs = bfq_attrs,
+ .elevator_name = "bfq",
+ .elevator_owner = THIS_MODULE,
+};
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+static struct blkcg_policy blkcg_policy_bfq = {
+ .dfl_cftypes = bfq_blkg_files,
+ .legacy_cftypes = bfq_blkcg_legacy_files,
+
+ .cpd_alloc_fn = bfq_cpd_alloc,
+ .cpd_init_fn = bfq_cpd_init,
+ .cpd_bind_fn = bfq_cpd_init,
+ .cpd_free_fn = bfq_cpd_free,
+
+ .pd_alloc_fn = bfq_pd_alloc,
+ .pd_init_fn = bfq_pd_init,
+ .pd_offline_fn = bfq_pd_offline,
+ .pd_free_fn = bfq_pd_free,
+ .pd_reset_stats_fn = bfq_pd_reset_stats,
+};
+#endif
+
+static int __init bfq_init(void)
+{
+ int ret;
+ char msg[50] = "BFQ I/O-scheduler: v8r3";
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ ret = blkcg_policy_register(&blkcg_policy_bfq);
+ if (ret)
+ return ret;
+#endif
+
+ ret = -ENOMEM;
+ if (bfq_slab_setup())
+ goto err_pol_unreg;
+
+ /*
+ * Times to load large popular applications for the typical systems
+ * installed on the reference devices (see the comments before the
+ * definitions of the two arrays).
+ */
+ T_slow[0] = msecs_to_jiffies(3500);
+ T_slow[1] = msecs_to_jiffies(1500);
+ T_fast[0] = msecs_to_jiffies(8000);
+ T_fast[1] = msecs_to_jiffies(3000);
+
+ /*
+ * Thresholds that determine the switch between speed classes
+ * (see the comments before the definition of the array
+ * device_speed_thresh). These thresholds are biased towards
+ * transitions to the fast class. This is safer than the
+ * opposite bias. In fact, a wrong transition to the slow
+ * class results in short weight-raising periods, because the
+ * speed of the device then tends to be higher that the
+ * reference peak rate. On the opposite end, a wrong
+ * transition to the fast class tends to increase
+ * weight-raising periods, because of the opposite reason.
+ */
+ device_speed_thresh[0] = (4 * R_slow[0]) / 3;
+ device_speed_thresh[1] = (4 * R_slow[1]) / 3;
+
+ ret = elv_register(&iosched_bfq);
+ if (ret)
+ goto err_pol_unreg;
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ strcat(msg, " (with cgroups support)");
+#endif
+ pr_info("%s", msg);
+
+ return 0;
+
+err_pol_unreg:
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ blkcg_policy_unregister(&blkcg_policy_bfq);
+#endif
+ return ret;
+}
+
+static void __exit bfq_exit(void)
+{
+ elv_unregister(&iosched_bfq);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ blkcg_policy_unregister(&blkcg_policy_bfq);
+#endif
+ bfq_slab_kill();
+}
+
+module_init(bfq_init);
+module_exit(bfq_exit);
+
+MODULE_AUTHOR("Arianna Avanzini, Fabio Checconi, Paolo Valente");
+MODULE_LICENSE("GPL");
diff -ruN linux-4.8/block/bfq-sched.c linux-bfq-bfq-v8/block/bfq-sched.c
--- linux-4.8/block/bfq-sched.c 1970-01-01 00:00:00.000000000 +0000
+++ linux-bfq-bfq-v8/block/bfq-sched.c 2016-10-06 07:08:26.000000000 +0000
@@ -0,0 +1,1501 @@
+/*
+ * BFQ: Hierarchical B-WF2Q+ scheduler.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org>
+ */
+
+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+#define for_each_entity(entity) \
+ for (; entity ; entity = entity->parent)
+
+#define for_each_entity_safe(entity, parent) \
+ for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
+
+
+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
+ int extract,
+ struct bfq_data *bfqd);
+
+static void bfq_update_budget(struct bfq_entity *next_in_service)
+{
+ struct bfq_entity *bfqg_entity;
+ struct bfq_group *bfqg;
+ struct bfq_sched_data *group_sd;
+
+ BUG_ON(!next_in_service);
+
+ group_sd = next_in_service->sched_data;
+
+ bfqg = container_of(group_sd, struct bfq_group, sched_data);
+ /*
+ * bfq_group's my_entity field is not NULL only if the group
+ * is not the root group. We must not touch the root entity
+ * as it must never become an in-service entity.
+ */
+ bfqg_entity = bfqg->my_entity;
+ if (bfqg_entity)
+ bfqg_entity->budget = next_in_service->budget;
+}
+
+static int bfq_update_next_in_service(struct bfq_sched_data *sd)
+{
+ struct bfq_entity *next_in_service;
+ struct bfq_queue *bfqq;
+
+ if (sd->in_service_entity)
+ /* will update/requeue at the end of service */
+ return 0;
+
+ /*
+ * NOTE: this can be improved in many ways, such as returning
+ * 1 (and thus propagating upwards the update) only when the
+ * budget changes, or caching the bfqq that will be scheduled
+ * next from this subtree. By now we worry more about
+ * correctness than about performance...
+ */
+ next_in_service = bfq_lookup_next_entity(sd, 0, NULL);
+ sd->next_in_service = next_in_service;
+
+ if (next_in_service)
+ bfq_update_budget(next_in_service);
+ else
+ goto exit;
+
+ bfqq = bfq_entity_to_bfqq(next_in_service);
+ if (bfqq)
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "update_next_in_service: chosen this queue");
+ else {
+ struct bfq_group *bfqg =
+ container_of(next_in_service,
+ struct bfq_group, entity);
+
+ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
+ "update_next_in_service: chosen this entity");
+ }
+exit:
+ return 1;
+}
+
+static void bfq_check_next_in_service(struct bfq_sched_data *sd,
+ struct bfq_entity *entity)
+{
+ WARN_ON(sd->next_in_service != entity);
+}
+#else
+#define for_each_entity(entity) \
+ for (; entity ; entity = NULL)
+
+#define for_each_entity_safe(entity, parent) \
+ for (parent = NULL; entity ; entity = parent)
+
+static int bfq_update_next_in_service(struct bfq_sched_data *sd)
+{
+ return 0;
+}
+
+static void bfq_check_next_in_service(struct bfq_sched_data *sd,
+ struct bfq_entity *entity)
+{
+}
+
+static void bfq_update_budget(struct bfq_entity *next_in_service)
+{
+}
+#endif
+
+/*
+ * Shift for timestamp calculations. This actually limits the maximum
+ * service allowed in one timestamp delta (small shift values increase it),
+ * the maximum total weight that can be used for the queues in the system
+ * (big shift values increase it), and the period of virtual time
+ * wraparounds.
+ */
+#define WFQ_SERVICE_SHIFT 22
+
+/**
+ * bfq_gt - compare two timestamps.
+ * @a: first ts.
+ * @b: second ts.
+ *
+ * Return @a > @b, dealing with wrapping correctly.
+ */
+static int bfq_gt(u64 a, u64 b)
+{
+ return (s64)(a - b) > 0;
+}
+
+static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = NULL;
+
+ BUG_ON(!entity);
+
+ if (!entity->my_sched_data)
+ bfqq = container_of(entity, struct bfq_queue, entity);
+
+ return bfqq;
+}
+
+
+/**
+ * bfq_delta - map service into the virtual time domain.
+ * @service: amount of service.
+ * @weight: scale factor (weight of an entity or weight sum).
+ */
+static u64 bfq_delta(unsigned long service, unsigned long weight)
+{
+ u64 d = (u64)service << WFQ_SERVICE_SHIFT;
+
+ do_div(d, weight);
+ return d;
+}
+
+/**
+ * bfq_calc_finish - assign the finish time to an entity.
+ * @entity: the entity to act upon.
+ * @service: the service to be charged to the entity.
+ */
+static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ unsigned long long start, finish, delta;
+
+ BUG_ON(entity->weight == 0);
+
+ entity->finish = entity->start +
+ bfq_delta(service, entity->weight);
+
+ start = ((entity->start>>10)*1000)>>12;
+ finish = ((entity->finish>>10)*1000)>>12;
+ delta = ((bfq_delta(service, entity->weight)>>10)*1000)>>12;
+
+ if (bfqq) {
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "calc_finish: serv %lu, w %d",
+ service, entity->weight);
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "calc_finish: start %llu, finish %llu, delta %llu",
+ start, finish, delta);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ } else {
+ struct bfq_group *bfqg =
+ container_of(entity, struct bfq_group, entity);
+
+ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
+ "calc_finish group: serv %lu, w %d",
+ service, entity->weight);
+ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
+ "calc_finish group: start %llu, finish %llu, delta %llu",
+ start, finish, delta);
+#endif
+ }
+}
+
+/**
+ * bfq_entity_of - get an entity from a node.
+ * @node: the node field of the entity.
+ *
+ * Convert a node pointer to the relative entity. This is used only
+ * to simplify the logic of some functions and not as the generic
+ * conversion mechanism because, e.g., in the tree walking functions,
+ * the check for a %NULL value would be redundant.
+ */
+static struct bfq_entity *bfq_entity_of(struct rb_node *node)
+{
+ struct bfq_entity *entity = NULL;
+
+ if (node)
+ entity = rb_entry(node, struct bfq_entity, rb_node);
+
+ return entity;
+}
+
+/**
+ * bfq_extract - remove an entity from a tree.
+ * @root: the tree root.
+ * @entity: the entity to remove.
+ */
+static void bfq_extract(struct rb_root *root, struct bfq_entity *entity)
+{
+ BUG_ON(entity->tree != root);
+
+ entity->tree = NULL;
+ rb_erase(&entity->rb_node, root);
+}
+
+/**
+ * bfq_idle_extract - extract an entity from the idle tree.
+ * @st: the service tree of the owning @entity.
+ * @entity: the entity being removed.
+ */
+static void bfq_idle_extract(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *next;
+
+ BUG_ON(entity->tree != &st->idle);
+
+ if (entity == st->first_idle) {
+ next = rb_next(&entity->rb_node);
+ st->first_idle = bfq_entity_of(next);
+ }
+
+ if (entity == st->last_idle) {
+ next = rb_prev(&entity->rb_node);
+ st->last_idle = bfq_entity_of(next);
+ }
+
+ bfq_extract(&st->idle, entity);
+
+ if (bfqq)
+ list_del(&bfqq->bfqq_list);
+}
+
+/**
+ * bfq_insert - generic tree insertion.
+ * @root: tree root.
+ * @entity: entity to insert.
+ *
+ * This is used for the idle and the active tree, since they are both
+ * ordered by finish time.
+ */
+static void bfq_insert(struct rb_root *root, struct bfq_entity *entity)
+{
+ struct bfq_entity *entry;
+ struct rb_node **node = &root->rb_node;
+ struct rb_node *parent = NULL;
+
+ BUG_ON(entity->tree);
+
+ while (*node) {
+ parent = *node;
+ entry = rb_entry(parent, struct bfq_entity, rb_node);
+
+ if (bfq_gt(entry->finish, entity->finish))
+ node = &parent->rb_left;
+ else
+ node = &parent->rb_right;
+ }
+
+ rb_link_node(&entity->rb_node, parent, node);
+ rb_insert_color(&entity->rb_node, root);
+
+ entity->tree = root;
+}
+
+/**
+ * bfq_update_min - update the min_start field of a entity.
+ * @entity: the entity to update.
+ * @node: one of its children.
+ *
+ * This function is called when @entity may store an invalid value for
+ * min_start due to updates to the active tree. The function assumes
+ * that the subtree rooted at @node (which may be its left or its right
+ * child) has a valid min_start value.
+ */
+static void bfq_update_min(struct bfq_entity *entity, struct rb_node *node)
+{
+ struct bfq_entity *child;
+
+ if (node) {
+ child = rb_entry(node, struct bfq_entity, rb_node);
+ if (bfq_gt(entity->min_start, child->min_start))
+ entity->min_start = child->min_start;
+ }
+}
+
+/**
+ * bfq_update_active_node - recalculate min_start.
+ * @node: the node to update.
+ *
+ * @node may have changed position or one of its children may have moved,
+ * this function updates its min_start value. The left and right subtrees
+ * are assumed to hold a correct min_start value.
+ */
+static void bfq_update_active_node(struct rb_node *node)
+{
+ struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node);
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ entity->min_start = entity->start;
+ bfq_update_min(entity, node->rb_right);
+ bfq_update_min(entity, node->rb_left);
+
+ if (bfqq) {
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "update_active_node: new min_start %llu",
+ ((entity->min_start>>10)*1000)>>12);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ } else {
+ struct bfq_group *bfqg =
+ container_of(entity, struct bfq_group, entity);
+
+ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
+ "update_active_node: new min_start %llu",
+ ((entity->min_start>>10)*1000)>>12);
+#endif
+ }
+}
+
+/**
+ * bfq_update_active_tree - update min_start for the whole active tree.
+ * @node: the starting node.
+ *
+ * @node must be the deepest modified node after an update. This function
+ * updates its min_start using the values held by its children, assuming
+ * that they did not change, and then updates all the nodes that may have
+ * changed in the path to the root. The only nodes that may have changed
+ * are the ones in the path or their siblings.
+ */
+static void bfq_update_active_tree(struct rb_node *node)
+{
+ struct rb_node *parent;
+
+up:
+ bfq_update_active_node(node);
+
+ parent = rb_parent(node);
+ if (!parent)
+ return;
+
+ if (node == parent->rb_left && parent->rb_right)
+ bfq_update_active_node(parent->rb_right);
+ else if (parent->rb_left)
+ bfq_update_active_node(parent->rb_left);
+
+ node = parent;
+ goto up;
+}
+
+static void bfq_weights_tree_add(struct bfq_data *bfqd,
+ struct bfq_entity *entity,
+ struct rb_root *root);
+
+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
+ struct bfq_entity *entity,
+ struct rb_root *root);
+
+
+/**
+ * bfq_active_insert - insert an entity in the active tree of its
+ * group/device.
+ * @st: the service tree of the entity.
+ * @entity: the entity being inserted.
+ *
+ * The active tree is ordered by finish time, but an extra key is kept
+ * per each node, containing the minimum value for the start times of
+ * its children (and the node itself), so it's possible to search for
+ * the eligible node with the lowest finish time in logarithmic time.
+ */
+static void bfq_active_insert(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *node = &entity->rb_node;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ struct bfq_sched_data *sd = NULL;
+ struct bfq_group *bfqg = NULL;
+ struct bfq_data *bfqd = NULL;
+#endif
+
+ bfq_insert(&st->active, entity);
+
+ if (node->rb_left)
+ node = node->rb_left;
+ else if (node->rb_right)
+ node = node->rb_right;
+
+ bfq_update_active_tree(node);
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ sd = entity->sched_data;
+ bfqg = container_of(sd, struct bfq_group, sched_data);
+ BUG_ON(!bfqg);
+ bfqd = (struct bfq_data *)bfqg->bfqd;
+#endif
+ if (bfqq)
+ list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else { /* bfq_group */
+ BUG_ON(!bfqd);
+ bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree);
+ }
+ if (bfqg != bfqd->root_group) {
+ BUG_ON(!bfqg);
+ BUG_ON(!bfqd);
+ bfqg->active_entities++;
+ }
+#endif
+}
+
+/**
+ * bfq_ioprio_to_weight - calc a weight from an ioprio.
+ * @ioprio: the ioprio value to convert.
+ */
+static unsigned short bfq_ioprio_to_weight(int ioprio)
+{
+ BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR);
+ return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF;
+}
+
+/**
+ * bfq_weight_to_ioprio - calc an ioprio from a weight.
+ * @weight: the weight value to convert.
+ *
+ * To preserve as much as possible the old only-ioprio user interface,
+ * 0 is used as an escape ioprio value for weights (numerically) equal or
+ * larger than IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF.
+ */
+static unsigned short bfq_weight_to_ioprio(int weight)
+{
+ BUG_ON(weight < BFQ_MIN_WEIGHT || weight > BFQ_MAX_WEIGHT);
+ return IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight < 0 ?
+ 0 : IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight;
+}
+
+static void bfq_get_entity(struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ if (bfqq) {
+ bfqq->ref++;
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d",
+ bfqq, bfqq->ref);
+ }
+}
+
+/**
+ * bfq_find_deepest - find the deepest node that an extraction can modify.
+ * @node: the node being removed.
+ *
+ * Do the first step of an extraction in an rb tree, looking for the
+ * node that will replace @node, and returning the deepest node that
+ * the following modifications to the tree can touch. If @node is the
+ * last node in the tree return %NULL.
+ */
+static struct rb_node *bfq_find_deepest(struct rb_node *node)
+{
+ struct rb_node *deepest;
+
+ if (!node->rb_right && !node->rb_left)
+ deepest = rb_parent(node);
+ else if (!node->rb_right)
+ deepest = node->rb_left;
+ else if (!node->rb_left)
+ deepest = node->rb_right;
+ else {
+ deepest = rb_next(node);
+ if (deepest->rb_right)
+ deepest = deepest->rb_right;
+ else if (rb_parent(deepest) != node)
+ deepest = rb_parent(deepest);
+ }
+
+ return deepest;
+}
+
+/**
+ * bfq_active_extract - remove an entity from the active tree.
+ * @st: the service_tree containing the tree.
+ * @entity: the entity being removed.
+ */
+static void bfq_active_extract(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *node;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ struct bfq_sched_data *sd = NULL;
+ struct bfq_group *bfqg = NULL;
+ struct bfq_data *bfqd = NULL;
+#endif
+
+ node = bfq_find_deepest(&entity->rb_node);
+ bfq_extract(&st->active, entity);
+
+ if (node)
+ bfq_update_active_tree(node);
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ sd = entity->sched_data;
+ bfqg = container_of(sd, struct bfq_group, sched_data);
+ BUG_ON(!bfqg);
+ bfqd = (struct bfq_data *)bfqg->bfqd;
+#endif
+ if (bfqq)
+ list_del(&bfqq->bfqq_list);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else { /* bfq_group */
+ BUG_ON(!bfqd);
+ bfq_weights_tree_remove(bfqd, entity,
+ &bfqd->group_weights_tree);
+ }
+ if (bfqg != bfqd->root_group) {
+ BUG_ON(!bfqg);
+ BUG_ON(!bfqd);
+ BUG_ON(!bfqg->active_entities);
+ bfqg->active_entities--;
+ }
+#endif
+}
+
+/**
+ * bfq_idle_insert - insert an entity into the idle tree.
+ * @st: the service tree containing the tree.
+ * @entity: the entity to insert.
+ */
+static void bfq_idle_insert(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct bfq_entity *first_idle = st->first_idle;
+ struct bfq_entity *last_idle = st->last_idle;
+
+ if (!first_idle || bfq_gt(first_idle->finish, entity->finish))
+ st->first_idle = entity;
+ if (!last_idle || bfq_gt(entity->finish, last_idle->finish))
+ st->last_idle = entity;
+
+ bfq_insert(&st->idle, entity);
+
+ if (bfqq)
+ list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list);
+}
+
+/**
+ * bfq_forget_entity - remove an entity from the wfq trees.
+ * @st: the service tree.
+ * @entity: the entity being removed.
+ *
+ * Update the device status and forget everything about @entity, putting
+ * the device reference to it, if it is a queue. Entities belonging to
+ * groups are not refcounted.
+ */
+static void bfq_forget_entity(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct bfq_sched_data *sd;
+
+ BUG_ON(!entity->on_st);
+
+ entity->on_st = 0;
+ st->wsum -= entity->weight;
+ if (bfqq) {
+ sd = entity->sched_data;
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity: %p %d",
+ bfqq, bfqq->ref);
+ bfq_put_queue(bfqq);
+ }
+}
+
+/**
+ * bfq_put_idle_entity - release the idle tree ref of an entity.
+ * @st: service tree for the entity.
+ * @entity: the entity being released.
+ */
+static void bfq_put_idle_entity(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ bfq_idle_extract(st, entity);
+ bfq_forget_entity(st, entity);
+}
+
+/**
+ * bfq_forget_idle - update the idle tree if necessary.
+ * @st: the service tree to act upon.
+ *
+ * To preserve the global O(log N) complexity we only remove one entry here;
+ * as the idle tree will not grow indefinitely this can be done safely.
+ */
+static void bfq_forget_idle(struct bfq_service_tree *st)
+{
+ struct bfq_entity *first_idle = st->first_idle;
+ struct bfq_entity *last_idle = st->last_idle;
+
+ if (RB_EMPTY_ROOT(&st->active) && last_idle &&
+ !bfq_gt(last_idle->finish, st->vtime)) {
+ /*
+ * Forget the whole idle tree, increasing the vtime past
+ * the last finish time of idle entities.
+ */
+ st->vtime = last_idle->finish;
+ }
+
+ if (first_idle && !bfq_gt(first_idle->finish, st->vtime))
+ bfq_put_idle_entity(st, first_idle);
+}
+
+static struct bfq_service_tree *
+__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
+ struct bfq_entity *entity)
+{
+ struct bfq_service_tree *new_st = old_st;
+
+ if (entity->prio_changed) {
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ unsigned int prev_weight, new_weight;
+ struct bfq_data *bfqd = NULL;
+ struct rb_root *root;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ struct bfq_sched_data *sd;
+ struct bfq_group *bfqg;
+#endif
+
+ if (bfqq)
+ bfqd = bfqq->bfqd;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else {
+ sd = entity->my_sched_data;
+ bfqg = container_of(sd, struct bfq_group, sched_data);
+ BUG_ON(!bfqg);
+ bfqd = (struct bfq_data *)bfqg->bfqd;
+ BUG_ON(!bfqd);
+ }
+#endif
+
+ BUG_ON(old_st->wsum < entity->weight);
+ old_st->wsum -= entity->weight;
+
+ if (entity->new_weight != entity->orig_weight) {
+ if (entity->new_weight < BFQ_MIN_WEIGHT ||
+ entity->new_weight > BFQ_MAX_WEIGHT) {
+ pr_crit("update_weight_prio: new_weight %d\n",
+ entity->new_weight);
+ if (entity->new_weight < BFQ_MIN_WEIGHT)
+ entity->new_weight = BFQ_MIN_WEIGHT;
+ else
+ entity->new_weight = BFQ_MAX_WEIGHT;
+ }
+ entity->orig_weight = entity->new_weight;
+ if (bfqq)
+ bfqq->ioprio =
+ bfq_weight_to_ioprio(entity->orig_weight);
+ }
+
+ if (bfqq)
+ bfqq->ioprio_class = bfqq->new_ioprio_class;
+ entity->prio_changed = 0;
+
+ /*
+ * NOTE: here we may be changing the weight too early,
+ * this will cause unfairness. The correct approach
+ * would have required additional complexity to defer
+ * weight changes to the proper time instants (i.e.,
+ * when entity->finish <= old_st->vtime).
+ */
+ new_st = bfq_entity_service_tree(entity);
+
+ prev_weight = entity->weight;
+ new_weight = entity->orig_weight *
+ (bfqq ? bfqq->wr_coeff : 1);
+ /*
+ * If the weight of the entity changes, remove the entity
+ * from its old weight counter (if there is a counter
+ * associated with the entity), and add it to the counter
+ * associated with its new weight.
+ */
+ if (prev_weight != new_weight) {
+ if (bfqq)
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "weight changed %d %d(%d %d)",
+ prev_weight, new_weight,
+ entity->orig_weight,
+ bfqq->wr_coeff);
+
+ root = bfqq ? &bfqd->queue_weights_tree :
+ &bfqd->group_weights_tree;
+ bfq_weights_tree_remove(bfqd, entity, root);
+ }
+ entity->weight = new_weight;
+ /*
+ * Add the entity to its weights tree only if it is
+ * not associated with a weight-raised queue.
+ */
+ if (prev_weight != new_weight &&
+ (bfqq ? bfqq->wr_coeff == 1 : 1))
+ /* If we get here, root has been initialized. */
+ bfq_weights_tree_add(bfqd, entity, root);
+
+ new_st->wsum += entity->weight;
+
+ if (new_st != old_st)
+ entity->start = new_st->vtime;
+ }
+
+ return new_st;
+}
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
+#endif
+
+/**
+ * bfq_bfqq_served - update the scheduler status after selection for
+ * service.
+ * @bfqq: the queue being served.
+ * @served: bytes to transfer.
+ *
+ * NOTE: this can be optimized, as the timestamps of upper level entities
+ * are synchronized every time a new bfqq is selected for service. By now,
+ * we keep it to better check consistency.
+ */
+static void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ struct bfq_service_tree *st;
+
+ for_each_entity(entity) {
+ st = bfq_entity_service_tree(entity);
+
+ entity->service += served;
+
+ BUG_ON(st->wsum == 0);
+
+ st->vtime += bfq_delta(served, st->wsum);
+ bfq_forget_idle(st);
+ }
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ bfqg_stats_set_start_empty_time(bfqq_group(bfqq));
+#endif
+ st = bfq_entity_service_tree(&bfqq->entity);
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs, vtime %llu on %p",
+ served, ((st->vtime>>10)*1000)>>12, st);
+}
+
+/**
+ * bfq_bfqq_charge_time - charge an amount of service equivalent to the length
+ * of the time interval during which bfqq has been in
+ * service.
+ * @bfqd: the device
+ * @bfqq: the queue that needs a service update.
+ * @time_ms: the amount of time during which the queue has received service
+ *
+ * If a queue does not consume its budget fast enough, then providing
+ * the queue with service fairness may impair throughput, more or less
+ * severely. For this reason, queues that consume their budget slowly
+ * are provided with time fairness instead of service fairness. This
+ * goal is achieved through the BFQ scheduling engine, even if such an
+ * engine works in the service, and not in the time domain. The trick
+ * is charging these queues with an inflated amount of service, equal
+ * to the amount of service that they would have received during their
+ * service slot if they had been fast, i.e., if their requests had
+ * been dispatched at a rate equal to the estimated peak rate.
+ *
+ * It is worth noting that time fairness can cause important
+ * distortions in terms of bandwidth distribution, on devices with
+ * internal queueing. The reason is that I/O requests dispatched
+ * during the service slot of a queue may be served after that service
+ * slot is finished, and may have a total processing time loosely
+ * correlated with the duration of the service slot. This is
+ * especially true for short service slots.
+ */
+static void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ unsigned long time_ms)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ int tot_serv_to_charge = entity->service;
+ unsigned int timeout_ms = jiffies_to_msecs(bfq_timeout);
+
+ if (time_ms > 0 && time_ms < timeout_ms)
+ tot_serv_to_charge =
+ (bfqd->bfq_max_budget * time_ms) / timeout_ms;
+
+ if (tot_serv_to_charge < entity->service)
+ tot_serv_to_charge = entity->service;
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "charge_time: %lu/%u ms, %d/%d/%d sectors",
+ time_ms, timeout_ms, entity->service,
+ tot_serv_to_charge, entity->budget);
+
+ /* Increase budget to avoid inconsistencies */
+ if (tot_serv_to_charge > entity->budget)
+ entity->budget = tot_serv_to_charge;
+
+ bfq_bfqq_served(bfqq,
+ max_t(int, 0, tot_serv_to_charge - entity->service));
+}
+
+/**
+ * __bfq_activate_entity - activate an entity.
+ * @entity: the entity being activated.
+ * @non_blocking_wait_rq: true if this entity was waiting for a request
+ *
+ * Called whenever an entity is activated, i.e., it is not active and one
+ * of its children receives a new request, or has to be reactivated due to
+ * budget exhaustion. It uses the current budget of the entity (and the
+ * service received if @entity is active) of the queue to calculate its
+ * timestamps.
+ */
+static void __bfq_activate_entity(struct bfq_entity *entity,
+ bool non_blocking_wait_rq)
+{
+ struct bfq_sched_data *sd = entity->sched_data;
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ bool backshifted = false;
+
+ BUG_ON(!sd);
+ BUG_ON(!st);
+ if (entity == sd->in_service_entity) {
+ BUG_ON(entity->tree);
+ /*
+ * If we are requeueing the current entity we have
+ * to take care of not charging to it service it has
+ * not received.
+ */
+ bfq_calc_finish(entity, entity->service);
+ entity->start = entity->finish;
+ sd->in_service_entity = NULL;
+ } else if (entity->tree == &st->active) {
+ /*
+ * Requeueing an entity due to a change of some
+ * next_in_service entity below it. We reuse the
+ * old start time.
+ */
+ bfq_active_extract(st, entity);
+ } else {
+ unsigned long long min_vstart;
+
+ /* See comments on bfq_fqq_update_budg_for_activation */
+ if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) {
+ backshifted = true;
+ min_vstart = entity->finish;
+ } else
+ min_vstart = st->vtime;
+
+ if (entity->tree == &st->idle) {
+ /*
+ * Must be on the idle tree, bfq_idle_extract() will
+ * check for that.
+ */
+ bfq_idle_extract(st, entity);
+ entity->start = bfq_gt(min_vstart, entity->finish) ?
+ min_vstart : entity->finish;
+ } else {
+ /*
+ * The finish time of the entity may be invalid, and
+ * it is in the past for sure, otherwise the queue
+ * would have been on the idle tree.
+ */
+ entity->start = min_vstart;
+ st->wsum += entity->weight;
+ bfq_get_entity(entity);
+
+ BUG_ON(entity->on_st);
+ entity->on_st = 1;
+ }
+ }
+
+ st = __bfq_entity_update_weight_prio(st, entity);
+ bfq_calc_finish(entity, entity->budget);
+
+ /*
+ * If some queues enjoy backshifting for a while, then their
+ * (virtual) finish timestamps may happen to become lower and
+ * lower than the system virtual time. In particular, if
+ * these queues often happen to be idle for short time
+ * periods, and during such time periods other queues with
+ * higher timestamps happen to be busy, then the backshifted
+ * timestamps of the former queues can become much lower than
+ * the system virtual time. In fact, to serve the queues with
+ * higher timestamps while the ones with lower timestamps are
+ * idle, the system virtual time may be pushed-up to much
+ * higher values than the finish timestamps of the idle
+ * queues. As a consequence, the finish timestamps of all new
+ * or newly activated queues may end up being much larger than
+ * those of lucky queues with backshifted timestamps. The
+ * latter queues may then monopolize the device for a lot of
+ * time. This would simply break service guarantees.
+ *
+ * To reduce this problem, push up a little bit the
+ * backshifted timestamps of the queue associated with this
+ * entity (only a queue can happen to have the backshifted
+ * flag set): just enough to let the finish timestamp of the
+ * queue be equal to the current value of the system virtual
+ * time. This may introduce a little unfairness among queues
+ * with backshifted timestamps, but it does not break
+ * worst-case fairness guarantees.
+ *
+ * As a special case, if bfqq is weight-raised, push up
+ * timestamps much less, to keep very low the probability that
+ * this push up causes the backshifted finish timestamps of
+ * weight-raised queues to become higher than the backshifted
+ * finish timestamps of non weight-raised queues.
+ */
+ if (backshifted && bfq_gt(st->vtime, entity->finish)) {
+ unsigned long delta = st->vtime - entity->finish;
+
+ if (bfqq)
+ delta /= bfqq->wr_coeff;
+
+ entity->start += delta;
+ entity->finish += delta;
+
+ if (bfqq) {
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "__activate_entity: new queue finish %llu",
+ ((entity->finish>>10)*1000)>>12);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ } else {
+ struct bfq_group *bfqg =
+ container_of(entity, struct bfq_group, entity);
+
+ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
+ "__activate_entity: new group finish %llu",
+ ((entity->finish>>10)*1000)>>12);
+#endif
+ }
+ }
+
+ bfq_active_insert(st, entity);
+
+ if (bfqq) {
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "__activate_entity: queue %seligible in st %p",
+ entity->start <= st->vtime ? "" : "non ", st);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ } else {
+ struct bfq_group *bfqg =
+ container_of(entity, struct bfq_group, entity);
+
+ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
+ "__activate_entity: group %seligible in st %p",
+ entity->start <= st->vtime ? "" : "non ", st);
+#endif
+ }
+}
+
+/**
+ * bfq_activate_entity - activate an entity and its ancestors if necessary.
+ * @entity: the entity to activate.
+ * @non_blocking_wait_rq: true if this entity was waiting for a request
+ *
+ * Activate @entity and all the entities on the path from it to the root.
+ */
+static void bfq_activate_entity(struct bfq_entity *entity,
+ bool non_blocking_wait_rq)
+{
+ struct bfq_sched_data *sd;
+
+ for_each_entity(entity) {
+ BUG_ON(!entity);
+ __bfq_activate_entity(entity, non_blocking_wait_rq);
+
+ sd = entity->sched_data;
+ if (!bfq_update_next_in_service(sd))
+ /*
+ * No need to propagate the activation to the
+ * upper entities, as they will be updated when
+ * the in-service entity is rescheduled.
+ */
+ break;
+ }
+}
+
+/**
+ * __bfq_deactivate_entity - deactivate an entity from its service tree.
+ * @entity: the entity to deactivate.
+ * @requeue: if false, the entity will not be put into the idle tree.
+ *
+ * Deactivate an entity, independently from its previous state. If the
+ * entity was not on a service tree just return, otherwise if it is on
+ * any scheduler tree, extract it from that tree, and if necessary
+ * and if the caller did not specify @requeue, put it on the idle tree.
+ *
+ * Return %1 if the caller should update the entity hierarchy, i.e.,
+ * if the entity was in service or if it was the next_in_service for
+ * its sched_data; return %0 otherwise.
+ */
+static int __bfq_deactivate_entity(struct bfq_entity *entity, int requeue)
+{
+ struct bfq_sched_data *sd = entity->sched_data;
+ struct bfq_service_tree *st;
+ int was_in_service;
+ int ret = 0;
+
+ if (sd == NULL || !entity->on_st) /* never activated, or inactive */
+ return 0;
+
+ st = bfq_entity_service_tree(entity);
+ was_in_service = entity == sd->in_service_entity;
+
+ BUG_ON(was_in_service && entity->tree);
+
+ if (was_in_service) {
+ bfq_calc_finish(entity, entity->service);
+ sd->in_service_entity = NULL;
+ } else if (entity->tree == &st->active)
+ bfq_active_extract(st, entity);
+ else if (entity->tree == &st->idle)
+ bfq_idle_extract(st, entity);
+ else if (entity->tree)
+ BUG();
+
+ if (was_in_service || sd->next_in_service == entity)
+ ret = bfq_update_next_in_service(sd);
+
+ if (!requeue || !bfq_gt(entity->finish, st->vtime))
+ bfq_forget_entity(st, entity);
+ else
+ bfq_idle_insert(st, entity);
+
+ BUG_ON(sd->in_service_entity == entity);
+ BUG_ON(sd->next_in_service == entity);
+
+ return ret;
+}
+
+/**
+ * bfq_deactivate_entity - deactivate an entity.
+ * @entity: the entity to deactivate.
+ * @requeue: true if the entity can be put on the idle tree
+ */
+static void bfq_deactivate_entity(struct bfq_entity *entity, int requeue)
+{
+ struct bfq_sched_data *sd;
+ struct bfq_entity *parent;
+
+ for_each_entity_safe(entity, parent) {
+ sd = entity->sched_data;
+
+ if (!__bfq_deactivate_entity(entity, requeue))
+ /*
+ * next_in_service has not been changed, so
+ * no upwards update is needed
+ */
+ break;
+
+ if (sd->next_in_service)
+ /*
+ * The parent entity is still backlogged,
+ * because next_in_service is not NULL, and
+ * next_in_service has been updated (see
+ * comment on the body of the above if):
+ * upwards update of the schedule is needed.
+ */
+ goto update;
+
+ /*
+ * If we get here, then the parent is no more backlogged and
+ * we want to propagate the deactivation upwards.
+ */
+ requeue = 1;
+ }
+
+ return;
+
+update:
+ entity = parent;
+ for_each_entity(entity) {
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ __bfq_activate_entity(entity, false);
+
+ sd = entity->sched_data;
+ if (bfqq)
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "invoking udpdate_next for this queue");
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else {
+ struct bfq_group *bfqg =
+ container_of(entity,
+ struct bfq_group, entity);
+
+ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
+ "invoking udpdate_next for this entity");
+ }
+#endif
+ if (!bfq_update_next_in_service(sd))
+ break;
+ }
+}
+
+/**
+ * bfq_update_vtime - update vtime if necessary.
+ * @st: the service tree to act upon.
+ *
+ * If necessary update the service tree vtime to have at least one
+ * eligible entity, skipping to its start time. Assumes that the
+ * active tree of the device is not empty.
+ *
+ * NOTE: this hierarchical implementation updates vtimes quite often,
+ * we may end up with reactivated processes getting timestamps after a
+ * vtime skip done because we needed a ->first_active entity on some
+ * intermediate node.
+ */
+static void bfq_update_vtime(struct bfq_service_tree *st)
+{
+ struct bfq_entity *entry;
+ struct rb_node *node = st->active.rb_node;
+
+ entry = rb_entry(node, struct bfq_entity, rb_node);
+ if (bfq_gt(entry->min_start, st->vtime)) {
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entry);
+ st->vtime = entry->min_start;
+
+ if (bfqq)
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "update_vtime: new vtime %llu %p",
+ ((st->vtime>>10)*1000)>>12, st);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else {
+ struct bfq_group *bfqg =
+ container_of(entry, struct bfq_group, entity);
+
+ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
+ "update_vtime: new vtime %llu %p",
+ ((st->vtime>>10)*1000)>>12, st);
+ }
+#endif
+ bfq_forget_idle(st);
+ }
+}
+
+/**
+ * bfq_first_active_entity - find the eligible entity with
+ * the smallest finish time
+ * @st: the service tree to select from.
+ *
+ * This function searches the first schedulable entity, starting from the
+ * root of the tree and going on the left every time on this side there is
+ * a subtree with at least one eligible (start >= vtime) entity. The path on
+ * the right is followed only if a) the left subtree contains no eligible
+ * entities and b) no eligible entity has been found yet.
+ */
+static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st)
+{
+ struct bfq_entity *entry, *first = NULL;
+ struct rb_node *node = st->active.rb_node;
+
+ while (node) {
+ entry = rb_entry(node, struct bfq_entity, rb_node);
+left:
+ if (!bfq_gt(entry->start, st->vtime))
+ first = entry;
+
+ BUG_ON(bfq_gt(entry->min_start, st->vtime));
+
+ if (node->rb_left) {
+ entry = rb_entry(node->rb_left,
+ struct bfq_entity, rb_node);
+ if (!bfq_gt(entry->min_start, st->vtime)) {
+ node = node->rb_left;
+ goto left;
+ }
+ }
+ if (first)
+ break;
+ node = node->rb_right;
+ }
+
+ BUG_ON(!first && !RB_EMPTY_ROOT(&st->active));
+ return first;
+}
+
+/**
+ * __bfq_lookup_next_entity - return the first eligible entity in @st.
+ * @st: the service tree.
+ *
+ * Update the virtual time in @st and return the first eligible entity
+ * it contains.
+ */
+static struct bfq_entity *
+__bfq_lookup_next_entity(struct bfq_service_tree *st, bool force)
+{
+ struct bfq_entity *entity, *new_next_in_service = NULL;
+ struct bfq_queue *bfqq;
+
+ if (RB_EMPTY_ROOT(&st->active))
+ return NULL;
+
+ bfq_update_vtime(st);
+ entity = bfq_first_active_entity(st);
+ BUG_ON(bfq_gt(entity->start, st->vtime));
+
+ bfqq = bfq_entity_to_bfqq(entity);
+ if (bfqq)
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "__lookup_next: start %llu vtime %llu st %p",
+ ((entity->start>>10)*1000)>>12,
+ ((st->vtime>>10)*1000)>>12, st);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else {
+ struct bfq_group *bfqg =
+ container_of(entity, struct bfq_group, entity);
+
+ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
+ "__lookup_next: start %llu vtime %llu st %p",
+ ((entity->start>>10)*1000)>>12,
+ ((st->vtime>>10)*1000)>>12, st);
+ }
+#endif
+
+ /*
+ * If the chosen entity does not match with the sched_data's
+ * next_in_service and we are forcedly serving the IDLE priority
+ * class tree, bubble up budget update.
+ */
+ if (unlikely(force && entity != entity->sched_data->next_in_service)) {
+ new_next_in_service = entity;
+ for_each_entity(new_next_in_service)
+ bfq_update_budget(new_next_in_service);
+ }
+
+ return entity;
+}
+
+/**
+ * bfq_lookup_next_entity - return the first eligible entity in @sd.
+ * @sd: the sched_data.
+ * @extract: if true the returned entity will be also extracted from @sd.
+ *
+ * NOTE: since we cache the next_in_service entity at each level of the
+ * hierarchy, the complexity of the lookup can be decreased with
+ * absolutely no effort just returning the cached next_in_service value;
+ * we prefer to do full lookups to test the consistency of * the data
+ * structures.
+ */
+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
+ int extract,
+ struct bfq_data *bfqd)
+{
+ struct bfq_service_tree *st = sd->service_tree;
+ struct bfq_entity *entity;
+ int i = 0;
+
+ BUG_ON(sd->in_service_entity);
+
+ /*
+ * Choose from idle class, if needed to guarantee a minimum
+ * bandwidth to this class. This should also mitigate
+ * priority-inversion problems in case a low priority task is
+ * holding file system resources.
+ */
+ if (bfqd &&
+ jiffies - bfqd->bfq_class_idle_last_service >
+ BFQ_CL_IDLE_TIMEOUT) {
+ entity = __bfq_lookup_next_entity(st + BFQ_IOPRIO_CLASSES - 1,
+ true);
+ if (entity) {
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ if (bfqq)
+ bfq_log_bfqq(bfqd, bfqq,
+ "idle chosen from st %p %d",
+ st + BFQ_IOPRIO_CLASSES - 1,
+ BFQ_IOPRIO_CLASSES - 1);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else {
+ struct bfq_group *bfqg =
+ container_of(entity, struct bfq_group, entity);
+
+ bfq_log_bfqg(bfqd, bfqg,
+ "idle chosen from st %p %d",
+ st + BFQ_IOPRIO_CLASSES - 1,
+ BFQ_IOPRIO_CLASSES - 1);
+ }
+#endif
+ i = BFQ_IOPRIO_CLASSES - 1;
+ bfqd->bfq_class_idle_last_service = jiffies;
+ sd->next_in_service = entity;
+ }
+ }
+ for (; i < BFQ_IOPRIO_CLASSES; i++) {
+ entity = __bfq_lookup_next_entity(st + i, false);
+ if (entity) {
+ if (bfqd != NULL) {
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ if (bfqq)
+ bfq_log_bfqq(bfqd, bfqq,
+ "chosen from st %p %d",
+ st + i, i);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else {
+ struct bfq_group *bfqg =
+ container_of(entity, struct bfq_group, entity);
+
+ bfq_log_bfqg(bfqd, bfqg,
+ "chosen from st %p %d",
+ st + i, i);
+ }
+#endif
+ }
+
+ if (extract) {
+ bfq_check_next_in_service(sd, entity);
+ bfq_active_extract(st + i, entity);
+ sd->in_service_entity = entity;
+ sd->next_in_service = NULL;
+ }
+ break;
+ }
+ }
+
+ return entity;
+}
+
+static bool next_queue_may_preempt(struct bfq_data *bfqd)
+{
+ struct bfq_sched_data *sd = &bfqd->root_group->sched_data;
+
+ return sd->next_in_service != sd->in_service_entity;
+}
+
+/*
+ * Get next queue for service.
+ */
+static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
+{
+ struct bfq_entity *entity = NULL;
+ struct bfq_sched_data *sd;
+ struct bfq_queue *bfqq;
+
+ BUG_ON(bfqd->in_service_queue);
+
+ if (bfqd->busy_queues == 0)
+ return NULL;
+
+ sd = &bfqd->root_group->sched_data;
+ for (; sd ; sd = entity->my_sched_data) {
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ if (entity) {
+ struct bfq_group *bfqg =
+ container_of(entity, struct bfq_group, entity);
+
+ bfq_log_bfqg(bfqd, bfqg,
+ "get_next_queue: lookup in this group");
+ } else
+ bfq_log_bfqg(bfqd, bfqd->root_group,
+ "get_next_queue: lookup in root group");
+#endif
+
+ entity = bfq_lookup_next_entity(sd, 1, bfqd);
+
+ bfqq = bfq_entity_to_bfqq(entity);
+ if (bfqq)
+ bfq_log_bfqq(bfqd, bfqq,
+ "get_next_queue: this queue, finish %llu",
+ (((entity->finish>>10)*1000)>>10)>>2);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else {
+ struct bfq_group *bfqg =
+ container_of(entity, struct bfq_group, entity);
+
+ bfq_log_bfqg(bfqd, bfqg,
+ "get_next_queue: this entity, finish %llu",
+ (((entity->finish>>10)*1000)>>10)>>2);
+ }
+#endif
+
+ BUG_ON(!entity);
+ entity->service = 0;
+ }
+
+ bfqq = bfq_entity_to_bfqq(entity);
+ BUG_ON(!bfqq);
+
+ return bfqq;
+}
+
+static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
+{
+ if (bfqd->in_service_bic) {
+ put_io_context(bfqd->in_service_bic->icq.ioc);
+ bfqd->in_service_bic = NULL;
+ }
+
+ bfq_clear_bfqq_wait_request(bfqd->in_service_queue);
+ hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
+ bfqd->in_service_queue = NULL;
+}
+
+static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ int requeue)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ BUG_ON(bfqq == bfqd->in_service_queue);
+ bfq_deactivate_entity(entity, requeue);
+}
+
+static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ bfq_activate_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq));
+ bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
+}
+
+static void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
+
+/*
+ * Called when the bfqq no longer has requests pending, remove it from
+ * the service tree.
+ */
+static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ int requeue)
+{
+ BUG_ON(!bfq_bfqq_busy(bfqq));
+ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
+ BUG_ON(bfqq == bfqd->in_service_queue);
+
+ bfq_log_bfqq(bfqd, bfqq, "del from busy");
+
+ bfq_clear_bfqq_busy(bfqq);
+
+ BUG_ON(bfqd->busy_queues == 0);
+ bfqd->busy_queues--;
+
+ if (!bfqq->dispatched)
+ bfq_weights_tree_remove(bfqd, &bfqq->entity,
+ &bfqd->queue_weights_tree);
+
+ if (bfqq->wr_coeff > 1)
+ bfqd->wr_busy_queues--;
+
+ bfqg_stats_update_dequeue(bfqq_group(bfqq));
+
+ BUG_ON(bfqq->entity.budget < 0);
+
+ bfq_deactivate_bfqq(bfqd, bfqq, requeue);
+
+ BUG_ON(bfqq->entity.budget < 0);
+}
+
+/*
+ * Called when an inactive queue receives a new request.
+ */
+static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ BUG_ON(bfq_bfqq_busy(bfqq));
+ BUG_ON(bfqq == bfqd->in_service_queue);
+
+ bfq_log_bfqq(bfqd, bfqq, "add to busy");
+
+ bfq_activate_bfqq(bfqd, bfqq);
+
+ bfq_mark_bfqq_busy(bfqq);
+ bfqd->busy_queues++;
+
+ if (!bfqq->dispatched)
+ if (bfqq->wr_coeff == 1)
+ bfq_weights_tree_add(bfqd, &bfqq->entity,
+ &bfqd->queue_weights_tree);
+
+ if (bfqq->wr_coeff > 1)
+ bfqd->wr_busy_queues++;
+}
diff -ruN linux-4.8/block/Kconfig.iosched linux-bfq-bfq-v8/block/Kconfig.iosched
--- linux-4.8/block/Kconfig.iosched 2016-10-02 23:24:33.000000000 +0000
+++ linux-bfq-bfq-v8/block/Kconfig.iosched 2016-10-06 07:08:26.000000000 +0000
@@ -39,6 +39,25 @@
---help---
Enable group IO scheduling in CFQ.
+config IOSCHED_BFQ
+ tristate "BFQ I/O scheduler"
+ default n
+ ---help---
+ The BFQ I/O scheduler tries to distribute bandwidth among
+ all processes according to their weights.
+ It aims at distributing the bandwidth as desired, independently of
+ the disk parameters and with any workload. It also tries to
+ guarantee low latency to interactive and soft real-time
+ applications. If compiled built-in (saying Y here), BFQ can
+ be configured to support hierarchical scheduling.
+
+config BFQ_GROUP_IOSCHED
+ bool "BFQ hierarchical scheduling support"
+ depends on IOSCHED_BFQ && BLK_CGROUP
+ default n
+ ---help---
+ Enable hierarchical scheduling in BFQ, using the blkio controller.
+
choice
prompt "Default I/O scheduler"
default DEFAULT_CFQ
@@ -52,6 +71,16 @@
config DEFAULT_CFQ
bool "CFQ" if IOSCHED_CFQ=y
+ config DEFAULT_BFQ
+ bool "BFQ" if IOSCHED_BFQ=y
+ help
+ Selects BFQ as the default I/O scheduler which will be
+ used by default for all block devices.
+ The BFQ I/O scheduler aims at distributing the bandwidth
+ as desired, independently of the disk parameters and with
+ any workload. It also tries to guarantee low latency to
+ interactive and soft real-time applications.
+
config DEFAULT_NOOP
bool "No-op"
@@ -61,6 +90,7 @@
string
default "deadline" if DEFAULT_DEADLINE
default "cfq" if DEFAULT_CFQ
+ default "bfq" if DEFAULT_BFQ
default "noop" if DEFAULT_NOOP
endmenu
diff -ruN linux-4.8/block/Makefile linux-bfq-bfq-v8/block/Makefile
--- linux-4.8/block/Makefile 2016-10-02 23:24:33.000000000 +0000
+++ linux-bfq-bfq-v8/block/Makefile 2016-10-06 07:08:26.000000000 +0000
@@ -18,6 +18,7 @@
obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o
+obj-$(CONFIG_IOSCHED_BFQ) += bfq-iosched.o
obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o
obj-$(CONFIG_BLK_CMDLINE_PARSER) += cmdline-parser.o
diff -ruN linux-4.8/include/linux/blkdev.h linux-bfq-bfq-v8/include/linux/blkdev.h
--- linux-4.8/include/linux/blkdev.h 2016-10-02 23:24:33.000000000 +0000
+++ linux-bfq-bfq-v8/include/linux/blkdev.h 2016-10-06 07:08:26.000000000 +0000
@@ -45,7 +45,7 @@
* Maximum number of blkcg policies allowed to be registered concurrently.
* Defined here to simplify include dependency.
*/
-#define BLKCG_MAX_POLS 2
+#define BLKCG_MAX_POLS 3
typedef void (rq_end_io_fn)(struct request *, int);
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