From 5e746da9817f9fee8f0d182c6fcc766ccf816017 Mon Sep 17 00:00:00 2001
From: ameerj <52414509+ameerj@users.noreply.github.com>
Date: Fri, 10 Feb 2023 20:43:06 -0500
Subject: [PATCH] kernel: Refactor thread_local variable usage
On MSVC at least, there seems to be a non-trivial overhead to calling GetHostThreadId().
This slightly reworks the host_thread_id variable to reduce some of the complexity around its usage, along with some small refactors around current_thread and dummy thread
---
src/core/hle/kernel/kernel.cpp | 43 ++++++++++++++--------------------
1 file changed, 17 insertions(+), 26 deletions(-)
diff --git a/src/core/hle/kernel/kernel.cpp b/src/core/hle/kernel/kernel.cpp
index d9eafe2613..ece20a6439 100644
--- a/src/core/hle/kernel/kernel.cpp
+++ b/src/core/hle/kernel/kernel.cpp
@@ -367,23 +367,21 @@ struct KernelCore::Impl {
current_process = process;
}
- static inline thread_local u32 host_thread_id = UINT32_MAX;
+ static inline thread_local u8 host_thread_id = UINT8_MAX;
- /// Gets the host thread ID for the caller, allocating a new one if this is the first time
- u32 GetHostThreadId(std::size_t core_id) {
- if (host_thread_id == UINT32_MAX) {
- // The first four slots are reserved for CPU core threads
- ASSERT(core_id < Core::Hardware::NUM_CPU_CORES);
- host_thread_id = static_cast<u32>(core_id);
- }
+ /// Sets the host thread ID for the caller.
+ u32 SetHostThreadId(std::size_t core_id) {
+ // This should only be called during core init.
+ ASSERT(host_thread_id == UINT8_MAX);
+
+ // The first four slots are reserved for CPU core threads
+ ASSERT(core_id < Core::Hardware::NUM_CPU_CORES);
+ host_thread_id = static_cast<u8>(core_id);
return host_thread_id;
}
- /// Gets the host thread ID for the caller, allocating a new one if this is the first time
- u32 GetHostThreadId() {
- if (host_thread_id == UINT32_MAX) {
- host_thread_id = next_host_thread_id++;
- }
+ /// Gets the host thread ID for the caller
+ u32 GetHostThreadId() const {
return host_thread_id;
}
@@ -391,23 +389,19 @@ struct KernelCore::Impl {
KThread* GetHostDummyThread(KThread* existing_thread) {
auto initialize = [this](KThread* thread) {
ASSERT(KThread::InitializeDummyThread(thread, nullptr).IsSuccess());
- thread->SetName(fmt::format("DummyThread:{}", GetHostThreadId()));
+ thread->SetName(fmt::format("DummyThread:{}", next_host_thread_id++));
return thread;
};
thread_local KThread raw_thread{system.Kernel()};
- thread_local KThread* thread = nullptr;
- if (thread == nullptr) {
- thread = (existing_thread == nullptr) ? initialize(&raw_thread) : existing_thread;
- }
-
+ thread_local KThread* thread = existing_thread ? existing_thread : initialize(&raw_thread);
return thread;
}
/// Registers a CPU core thread by allocating a host thread ID for it
void RegisterCoreThread(std::size_t core_id) {
ASSERT(core_id < Core::Hardware::NUM_CPU_CORES);
- const auto this_id = GetHostThreadId(core_id);
+ const auto this_id = SetHostThreadId(core_id);
if (!is_multicore) {
single_core_thread_id = this_id;
}
@@ -415,7 +409,6 @@ struct KernelCore::Impl {
/// Registers a new host thread by allocating a host thread ID for it
void RegisterHostThread(KThread* existing_thread) {
- [[maybe_unused]] const auto this_id = GetHostThreadId();
[[maybe_unused]] const auto dummy_thread = GetHostDummyThread(existing_thread);
}
@@ -445,11 +438,9 @@ struct KernelCore::Impl {
static inline thread_local KThread* current_thread{nullptr};
KThread* GetCurrentEmuThread() {
- const auto thread_id = GetCurrentHostThreadID();
- if (thread_id >= Core::Hardware::NUM_CPU_CORES) {
- return GetHostDummyThread(nullptr);
+ if (!current_thread) {
+ current_thread = GetHostDummyThread(nullptr);
}
-
return current_thread;
}
@@ -1002,7 +993,7 @@ const Kernel::PhysicalCore& KernelCore::CurrentPhysicalCore() const {
}
Kernel::KScheduler* KernelCore::CurrentScheduler() {
- u32 core_id = impl->GetCurrentHostThreadID();
+ const u32 core_id = impl->GetCurrentHostThreadID();
if (core_id >= Core::Hardware::NUM_CPU_CORES) {
// This is expected when called from not a guest thread
return {};