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runtime: inline size to class conversion in malloc() 

Also change table type from int32[] to int8[] to save space in L1$.

benchmark          old ns/op    new ns/op    delta
BenchmarkMalloc           42           40   -4.68%

R=golang-dev, bradfitz, r
CC=golang-dev
https://golang.org/cl/9199044
This commit is contained in:
Dmitriy Vyukov 2013-05-15 11:02:33 +04:00
parent 3de593d94b
commit 5a89b35bca
3 changed files with 22 additions and 14 deletions
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6
src/pkg/runtime/malloc.goc
View File

@ -50,7 +50,11 @@ runtime·mallocgc(uintptr size, uint32 flag, int32 dogc, int32 zeroed)
c->local_nmalloc++;
if(size <= MaxSmallSize) {
// Allocate from mcache free lists.
sizeclass = runtime·SizeToClass(size);
// Inlined version of SizeToClass().
if(size <= 1024-8)
sizeclass = runtime·size_to_class8[(size+7)>>3];
else
sizeclass = runtime·size_to_class128[(size-1024+127) >> 7];
size = runtime·class_to_size[sizeclass];
v = runtime·MCache_Alloc(c, sizeclass, size, zeroed);
if(v == nil)

2
src/pkg/runtime/malloc.h
View File

@ -275,6 +275,8 @@ int32 runtime·SizeToClass(int32);
extern int32 runtime·class_to_size[NumSizeClasses];
extern int32 runtime·class_to_allocnpages[NumSizeClasses];
extern int32 runtime·class_to_transfercount[NumSizeClasses];
extern int8 runtime·size_to_class8[1024/8 + 1];
extern int8 runtime·size_to_class128[(MaxSmallSize-1024)/128 + 1];
extern void runtime·InitSizes(void);

28
src/pkg/runtime/msize.c
View File

@ -42,17 +42,17 @@ int32 runtime·class_to_transfercount[NumSizeClasses];
// size divided by 128 (rounded up). The arrays are filled in
// by InitSizes.
static int32 size_to_class8[1024/8 + 1];
static int32 size_to_class128[(MaxSmallSize-1024)/128 + 1];
int8 runtime·size_to_class8[1024/8 + 1];
int8 runtime·size_to_class128[(MaxSmallSize-1024)/128 + 1];
int32
runtime·SizeToClass(int32 size)
static int32
SizeToClass(int32 size)
{
if(size > MaxSmallSize)
runtime·throw("SizeToClass - invalid size");
if(size > 1024-8)
return size_to_class128[(size-1024+127) >> 7];
return size_to_class8[(size+7)>>3];
return runtime·size_to_class128[(size-1024+127) >> 7];
return runtime·size_to_class8[(size+7)>>3];
}
void
@ -111,16 +111,16 @@ runtime·InitSizes(void)
nextsize = 0;
for (sizeclass = 1; sizeclass < NumSizeClasses; sizeclass++) {
for(; nextsize < 1024 && nextsize <= runtime·class_to_size[sizeclass]; nextsize+=8)
size_to_class8[nextsize/8] = sizeclass;
runtime·size_to_class8[nextsize/8] = sizeclass;
if(nextsize >= 1024)
for(; nextsize <= runtime·class_to_size[sizeclass]; nextsize += 128)
size_to_class128[(nextsize-1024)/128] = sizeclass;
runtime·size_to_class128[(nextsize-1024)/128] = sizeclass;
}
// Double-check SizeToClass.
if(0) {
for(n=0; n < MaxSmallSize; n++) {
sizeclass = runtime·SizeToClass(n);
sizeclass = SizeToClass(n);
if(sizeclass < 1 || sizeclass >= NumSizeClasses || runtime·class_to_size[sizeclass] < n) {
runtime·printf("size=%d sizeclass=%d runtime·class_to_size=%d\n", n, sizeclass, runtime·class_to_size[sizeclass]);
runtime·printf("incorrect SizeToClass");
@ -157,12 +157,14 @@ dump:
runtime·printf(" %d", runtime·class_to_size[sizeclass]);
runtime·printf("\n\n");
runtime·printf("size_to_class8:");
for(i=0; i<nelem(size_to_class8); i++)
runtime·printf(" %d=>%d(%d)\n", i*8, size_to_class8[i], runtime·class_to_size[size_to_class8[i]]);
for(i=0; i<nelem(runtime·size_to_class8); i++)
runtime·printf(" %d=>%d(%d)\n", i*8, runtime·size_to_class8[i],
runtime·class_to_size[runtime·size_to_class8[i]]);
runtime·printf("\n");
runtime·printf("size_to_class128:");
for(i=0; i<nelem(size_to_class128); i++)
runtime·printf(" %d=>%d(%d)\n", i*128, size_to_class128[i], runtime·class_to_size[size_to_class128[i]]);
for(i=0; i<nelem(runtime·size_to_class128); i++)
runtime·printf(" %d=>%d(%d)\n", i*128, runtime·size_to_class128[i],
runtime·class_to_size[runtime·size_to_class128[i]]);
runtime·printf("\n");
}
runtime·throw("InitSizes failed");