qbit/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-11-18 09:54:57 -07:00
Code Releases Activity

runtime: Add prefetch to allocation code

Browse Source 
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>
This commit is contained in:
Rick Hudson 2015-02-19 18:11:24 -05:00
parent 96333a7e48
commit 99482f2f9e
1 changed files with 4 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
src/runtime/malloc.go
View File

@ -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