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| author | Rick Hudson <rlh@golang.org> | 2015-02-19 18:11:24 -0500 |
|---|---|---|
| committer | Rick Hudson <rlh@golang.org> | 2015-02-23 18:52:43 +0000 |
| commit | 99482f2f9e7710206386ff45869cb76a53e0ac76 (patch) | |
| tree | 7d0d9c476fcf6d82035bc3c124e7a0e70766e453 | |
| parent | 96333a7e4841c37d4c70cdab8748f9e69012cf29 (diff) | |
| download | go-99482f2f9e7710206386ff45869cb76a53e0ac76.tar.gz go-99482f2f9e7710206386ff45869cb76a53e0ac76.zip | |
runtime: Add prefetch to allocation code
The routine mallocgc retrieves objects from freelists. Prefetch
the object that will be returned in the next call to mallocgc.
Experiments indicate that this produces a 1% improvement when using
prefetchnta and less when using prefetcht0, prefetcht1, or prefetcht2.
Benchmark numbers indicate a 1% improvement over no
prefetch, much less over prefetcht0, prefetcht1, and prefetcht2.
These numbers were for the garbage benchmark with MAXPROCS=4
no prefetch >> 5.96 / 5.77 / 5.89
prefetcht0(uintptr(v.ptr().next)) >> 5.88 / 6.17 / 5.84
prefetcht1(uintptr(v.ptr().next)) >> 5.88 / 5.89 / 5.91
prefetcht2(uintptr(v.ptr().next)) >> 5.87 / 6.47 / 5.92
prefetchnta(uintptr(v.ptr().next)) >> 5.72 / 5.84 / 5.85
Change-Id: I54e07172081cccb097d5b5ce8789d74daa055ed9
Reviewed-on: https://go-review.googlesource.com/5350
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Austin Clements <austin@google.com>
| -rw-r--r-- | src/runtime/malloc.go | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go index 475f97fd05..fac5ca49ce 100644 --- a/src/runtime/malloc.go +++ b/src/runtime/malloc.go @@ -553,7 +553,8 @@ func mallocgc(size uintptr, typ *_type, flags uint32) unsafe.Pointer { } s.freelist = v.ptr().next s.ref++ - //TODO: prefetch v.next + // prefetchnta offers best performance, see change list message. + prefetchnta(uintptr(v.ptr().next)) x = unsafe.Pointer(v) (*[2]uint64)(x)[0] = 0 (*[2]uint64)(x)[1] = 0 @@ -584,7 +585,8 @@ func mallocgc(size uintptr, typ *_type, flags uint32) unsafe.Pointer { } s.freelist = v.ptr().next s.ref++ - //TODO: prefetch + // prefetchnta offers best performance, see change list message. + prefetchnta(uintptr(v.ptr().next)) x = unsafe.Pointer(v) if flags&flagNoZero == 0 { v.ptr().next = 0 |