project-base/server-skynet-source-3rd-jemalloc
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Don't junk-fill reallocations unless usize changes.

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Don't junk fill reallocations for which the request size is less than
the current usable size, but not enough smaller to cause a size class
change.  Unlike malloc()/calloc()/realloc(), *allocx() contractually
treats the full usize as the allocation, so a caller can ask for zeroed
memory via mallocx() and a series of rallocx() calls that all specify
MALLOCX_ZERO, and be assured that all newly allocated bytes will be
zeroed and made available to the application without danger of allocator
mutation until the size class decreases enough to cause usize reduction.
This commit is contained in:
Jason Evans 2013-12-15 21:49:40 -08:00
parent 665769357c
commit 6e62984ef6
3 changed files with 4 additions and 16 deletions
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1
include/jemalloc/internal/tcache.h
View File

@ -297,6 +297,7 @@ tcache_alloc_small(tcache_t *tcache, size_t size, bool zero)
binind = SMALL_SIZE2BIN(size); binind = SMALL_SIZE2BIN(size);
assert(binind < NBINS); assert(binind < NBINS);
tbin = &tcache->tbins[binind]; tbin = &tcache->tbins[binind];
size = arena_bin_info[binind].reg_size;
ret = tcache_alloc_easy(tbin); ret = tcache_alloc_easy(tbin);
if (ret == NULL) { if (ret == NULL) {
ret = tcache_alloc_small_hard(tcache, tbin, binind); ret = tcache_alloc_small_hard(tcache, tbin, binind);

15
src/arena.c
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@ -1938,10 +1938,6 @@ arena_ralloc_large(void *ptr, size_t oldsize, size_t size, size_t extra,
psize = PAGE_CEILING(size + extra); psize = PAGE_CEILING(size + extra);
if (psize == oldsize) { if (psize == oldsize) {
/* Same size class. */ /* Same size class. */
if (config_fill && opt_junk && size < oldsize) {
memset((void *)((uintptr_t)ptr + size), 0x5a, oldsize -
size);
}
return (false); return (false);
} else { } else {
arena_chunk_t *chunk; arena_chunk_t *chunk;
@ -1953,8 +1949,8 @@ arena_ralloc_large(void *ptr, size_t oldsize, size_t size, size_t extra,
if (psize < oldsize) { if (psize < oldsize) {
/* Fill before shrinking in order avoid a race. */ /* Fill before shrinking in order avoid a race. */
if (config_fill && opt_junk) { if (config_fill && opt_junk) {
memset((void *)((uintptr_t)ptr + size), 0x5a, memset((void *)((uintptr_t)ptr + psize), 0x5a,
oldsize - size); oldsize - psize);
} }
arena_ralloc_large_shrink(arena, chunk, ptr, oldsize, arena_ralloc_large_shrink(arena, chunk, ptr, oldsize,
psize); psize);
@ -1988,13 +1984,8 @@ arena_ralloc_no_move(void *ptr, size_t oldsize, size_t size, size_t extra,
if ((size + extra <= SMALL_MAXCLASS && if ((size + extra <= SMALL_MAXCLASS &&
SMALL_SIZE2BIN(size + extra) == SMALL_SIZE2BIN(size + extra) ==
SMALL_SIZE2BIN(oldsize)) || (size <= oldsize && SMALL_SIZE2BIN(oldsize)) || (size <= oldsize &&
size + extra >= oldsize)) { size + extra >= oldsize))
if (config_fill && opt_junk && size < oldsize) {
memset((void *)((uintptr_t)ptr + size),
0x5a, oldsize - size);
}
return (ptr); return (ptr);
}
} else { } else {
assert(size <= arena_maxclass); assert(size <= arena_maxclass);
if (size + extra > SMALL_MAXCLASS) { if (size + extra > SMALL_MAXCLASS) {

4
src/huge.c
View File

@ -89,10 +89,6 @@ huge_ralloc_no_move(void *ptr, size_t oldsize, size_t size, size_t extra)
&& CHUNK_CEILING(oldsize) >= CHUNK_CEILING(size) && CHUNK_CEILING(oldsize) >= CHUNK_CEILING(size)
&& CHUNK_CEILING(oldsize) <= CHUNK_CEILING(size+extra)) { && CHUNK_CEILING(oldsize) <= CHUNK_CEILING(size+extra)) {
assert(CHUNK_CEILING(oldsize) == oldsize); assert(CHUNK_CEILING(oldsize) == oldsize);
if (config_fill && opt_junk && size < oldsize) {
memset((void *)((uintptr_t)ptr + size), 0x5a,
oldsize - size);
}
return (ptr); return (ptr);
} }