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lib/uint64set: improve Set.Has() performance scalability on multi-CPU system

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Do not update bucket32.hint on Set.Has() call, since it leads to memory ping-pong between CPU cores multi-CPU system
This commit is contained in:
Aliaksandr Valialkin 2021-03-29 12:32:27 +03:00
parent 2601cc0fb0
commit b75c2ce659
1 changed files with 2 additions and 24 deletions
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26
lib/uint64set/uint64set.go
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@ -186,19 +186,6 @@ func (s *Set) Has(x uint64) bool {
hi32 := uint32(x >> 32)
lo32 := uint32(x)
bs := s.buckets
if len(bs) > 0 && bs[0].hi == hi32 {
// Manually inline bucket32.has for performance reasons.
hi16 := uint16(lo32 >> 16)
lo16 := uint16(lo32)
b32 := &bs[0]
his := b32.b16his
if n := b32.getHint(); n < uint32(len(his)) && his[n] == hi16 {
// Fast path - check the previously used bucket.
bs := b32.buckets
return n < uint32(len(bs)) && bs[n].has(lo16)
}
return b32.hasSlow(hi16, lo16)
}
for i := range bs {
b32 := &bs[i]
if b32.hi == hi32 {
@ -671,22 +658,13 @@ func (b *bucket32) addBucketAtPos(hi uint16, pos int) *bucket16 {
func (b *bucket32) has(x uint32) bool {
hi := uint16(x >> 16)
lo := uint16(x)
his := b.b16his
if n := b.getHint(); n < uint32(len(his)) && his[n] == hi {
// Fast path - check the previously used bucket.
bs := b.buckets
return n < uint32(len(bs)) && bs[n].has(lo)
}
return b.hasSlow(hi, lo)
}
func (b *bucket32) hasSlow(hi, lo uint16) bool {
his := b.b16his
n := binarySearch16(his, hi)
if n < 0 || n >= len(his) || his[n] != hi {
return false
}
b.setHint(n)
// Do not call b.setHint(n) here, since this may trash performance
// when many concurrent goroutines call b.has() method from many CPU cores.
bs := b.buckets
return n < len(bs) && bs[n].has(lo)
}