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Diffstat (limited to 'src/runtime/msize.c')
| -rw-r--r-- | src/runtime/msize.c | 184 |
1 files changed, 0 insertions, 184 deletions
diff --git a/src/runtime/msize.c b/src/runtime/msize.c deleted file mode 100644 index 7cb65dad0..000000000 --- a/src/runtime/msize.c +++ /dev/null @@ -1,184 +0,0 @@ -// Copyright 2009 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// Malloc small size classes. -// -// See malloc.h for overview. -// -// The size classes are chosen so that rounding an allocation -// request up to the next size class wastes at most 12.5% (1.125x). -// -// Each size class has its own page count that gets allocated -// and chopped up when new objects of the size class are needed. -// That page count is chosen so that chopping up the run of -// pages into objects of the given size wastes at most 12.5% (1.125x) -// of the memory. It is not necessary that the cutoff here be -// the same as above. -// -// The two sources of waste multiply, so the worst possible case -// for the above constraints would be that allocations of some -// size might have a 26.6% (1.266x) overhead. -// In practice, only one of the wastes comes into play for a -// given size (sizes < 512 waste mainly on the round-up, -// sizes > 512 waste mainly on the page chopping). -// -// TODO(rsc): Compute max waste for any given size. - -#include "runtime.h" -#include "arch_GOARCH.h" -#include "malloc.h" -#include "textflag.h" - -#pragma dataflag NOPTR -int32 runtime·class_to_size[NumSizeClasses]; -#pragma dataflag NOPTR -int32 runtime·class_to_allocnpages[NumSizeClasses]; - -// The SizeToClass lookup is implemented using two arrays, -// one mapping sizes <= 1024 to their class and one mapping -// sizes >= 1024 and <= MaxSmallSize to their class. -// All objects are 8-aligned, so the first array is indexed by -// the size divided by 8 (rounded up). Objects >= 1024 bytes -// are 128-aligned, so the second array is indexed by the -// size divided by 128 (rounded up). The arrays are filled in -// by InitSizes. - -#pragma dataflag NOPTR -int8 runtime·size_to_class8[1024/8 + 1]; -#pragma dataflag NOPTR -int8 runtime·size_to_class128[(MaxSmallSize-1024)/128 + 1]; - -void runtime·testdefersizes(void); - -int32 -runtime·SizeToClass(int32 size) -{ - if(size > MaxSmallSize) - runtime·throw("SizeToClass - invalid size"); - if(size > 1024-8) - return runtime·size_to_class128[(size-1024+127) >> 7]; - return runtime·size_to_class8[(size+7)>>3]; -} - -void -runtime·InitSizes(void) -{ - int32 align, sizeclass, size, nextsize, n; - uint32 i; - uintptr allocsize, npages; - - // Initialize the runtime·class_to_size table (and choose class sizes in the process). - runtime·class_to_size[0] = 0; - sizeclass = 1; // 0 means no class - align = 8; - for(size = align; size <= MaxSmallSize; size += align) { - if((size&(size-1)) == 0) { // bump alignment once in a while - if(size >= 2048) - align = 256; - else if(size >= 128) - align = size / 8; - else if(size >= 16) - align = 16; // required for x86 SSE instructions, if we want to use them - } - if((align&(align-1)) != 0) - runtime·throw("InitSizes - bug"); - - // Make the allocnpages big enough that - // the leftover is less than 1/8 of the total, - // so wasted space is at most 12.5%. - allocsize = PageSize; - while(allocsize%size > allocsize/8) - allocsize += PageSize; - npages = allocsize >> PageShift; - - // If the previous sizeclass chose the same - // allocation size and fit the same number of - // objects into the page, we might as well - // use just this size instead of having two - // different sizes. - if(sizeclass > 1 && - npages == runtime·class_to_allocnpages[sizeclass-1] && - allocsize/size == allocsize/runtime·class_to_size[sizeclass-1]) { - runtime·class_to_size[sizeclass-1] = size; - continue; - } - - runtime·class_to_allocnpages[sizeclass] = npages; - runtime·class_to_size[sizeclass] = size; - sizeclass++; - } - if(sizeclass != NumSizeClasses) { - runtime·printf("sizeclass=%d NumSizeClasses=%d\n", sizeclass, NumSizeClasses); - runtime·throw("InitSizes - bad NumSizeClasses"); - } - - // Initialize the size_to_class tables. - nextsize = 0; - for (sizeclass = 1; sizeclass < NumSizeClasses; sizeclass++) { - for(; nextsize < 1024 && nextsize <= runtime·class_to_size[sizeclass]; nextsize+=8) - runtime·size_to_class8[nextsize/8] = sizeclass; - if(nextsize >= 1024) - for(; nextsize <= runtime·class_to_size[sizeclass]; nextsize += 128) - runtime·size_to_class128[(nextsize-1024)/128] = sizeclass; - } - - // Double-check SizeToClass. - if(0) { - for(n=0; n < MaxSmallSize; n++) { - sizeclass = runtime·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"); - goto dump; - } - if(sizeclass > 1 && runtime·class_to_size[sizeclass-1] >= n) { - runtime·printf("size=%d sizeclass=%d runtime·class_to_size=%d\n", n, sizeclass, runtime·class_to_size[sizeclass]); - runtime·printf("SizeToClass too big"); - goto dump; - } - } - } - - runtime·testdefersizes(); - - // Copy out for statistics table. - for(i=0; i<nelem(runtime·class_to_size); i++) - mstats.by_size[i].size = runtime·class_to_size[i]; - return; - -dump: - if(1){ - runtime·printf("NumSizeClasses=%d\n", NumSizeClasses); - runtime·printf("runtime·class_to_size:"); - for(sizeclass=0; sizeclass<NumSizeClasses; sizeclass++) - runtime·printf(" %d", runtime·class_to_size[sizeclass]); - runtime·printf("\n\n"); - runtime·printf("size_to_class8:"); - 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(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"); -} - -// Returns size of the memory block that mallocgc will allocate if you ask for the size. -uintptr -runtime·roundupsize(uintptr size) -{ - if(size < MaxSmallSize) { - if(size <= 1024-8) - return runtime·class_to_size[runtime·size_to_class8[(size+7)>>3]]; - else - return runtime·class_to_size[runtime·size_to_class128[(size-1024+127) >> 7]]; - } - if(size + PageSize < size) - return size; - return ROUND(size, PageSize); -} |