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runtime: call mallocgc directly from makeslice and growslice

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The extra checks provided by newarray are
redundant in these cases.

This shrinks by one frame the call stack expected
by the pprof test.

name                      old time/op  new time/op  delta
MakeSlice-8               34.3ns ± 2%  30.5ns ± 3%  -11.03%  (p=0.000 n=24+22)
GrowSlicePtr-8             134ns ± 2%   129ns ± 3%   -3.25%  (p=0.000 n=25+24)

Change-Id: Icd828655906b921c732701fd9d61da3fa217b0af
Reviewed-on: https://go-review.googlesource.com/22276
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2016-04-19 15:14:26 -07:00
parent 7b0ba1cff8
commit 0150f15a92
2 changed files with 8 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/runtime/pprof/mprof_test.go
View File

@ -82,7 +82,7 @@ func TestMemoryProfiler(t *testing.T) {
# 0x[0-9,a-f]+ runtime/pprof_test\.TestMemoryProfiler\+0x[0-9,a-f]+ .*/runtime/pprof/mprof_test.go:61 # 0x[0-9,a-f]+ runtime/pprof_test\.TestMemoryProfiler\+0x[0-9,a-f]+ .*/runtime/pprof/mprof_test.go:61
`, (1<<10)*memoryProfilerRun, (1<<20)*memoryProfilerRun), `, (1<<10)*memoryProfilerRun, (1<<20)*memoryProfilerRun),
fmt.Sprintf(`0: 0 \[%v: %v\] @ 0x[0-9,a-f]+ 0x[0-9,a-f]+ 0x[0-9,a-f]+ 0x[0-9,a-f]+ 0x[0-9,a-f]+ fmt.Sprintf(`0: 0 \[%v: %v\] @ 0x[0-9,a-f]+ 0x[0-9,a-f]+ 0x[0-9,a-f]+ 0x[0-9,a-f]+
# 0x[0-9,a-f]+ runtime/pprof_test\.allocateTransient2M\+0x[0-9,a-f]+ .*/runtime/pprof/mprof_test.go:27 # 0x[0-9,a-f]+ runtime/pprof_test\.allocateTransient2M\+0x[0-9,a-f]+ .*/runtime/pprof/mprof_test.go:27
# 0x[0-9,a-f]+ runtime/pprof_test\.TestMemoryProfiler\+0x[0-9,a-f]+ .*/runtime/pprof/mprof_test.go:62 # 0x[0-9,a-f]+ runtime/pprof_test\.TestMemoryProfiler\+0x[0-9,a-f]+ .*/runtime/pprof/mprof_test.go:62
`, memoryProfilerRun, (2<<20)*memoryProfilerRun), `, memoryProfilerRun, (2<<20)*memoryProfilerRun),

9
src/runtime/slice.go
View File

@ -55,7 +55,12 @@ func makeslice(t *slicetype, len64, cap64 int64) slice {
panic(errorString("makeslice: cap out of range")) panic(errorString("makeslice: cap out of range"))
} }
p := newarray(t.elem, uintptr(cap)) et := t.elem
var flags uint32
if et.kind&kindNoPointers != 0 {
flags = flagNoScan
}
p := mallocgc(et.size*uintptr(cap), et, flags)
return slice{p, len, cap} return slice{p, len, cap}
} }
@ -130,7 +135,7 @@ func growslice(t *slicetype, old slice, cap int) slice {
memclr(add(p, lenmem), capmem-lenmem) memclr(add(p, lenmem), capmem-lenmem)
} else { } else {
// Note: can't use rawmem (which avoids zeroing of memory), because then GC can scan uninitialized memory. // Note: can't use rawmem (which avoids zeroing of memory), because then GC can scan uninitialized memory.
p = newarray(et, uintptr(newcap)) p = mallocgc(capmem, et, 0)
if !writeBarrier.enabled { if !writeBarrier.enabled {
memmove(p, old.array, lenmem) memmove(p, old.array, lenmem)
} else { } else {