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Fast-path improvement: reduce # of branches and unnecessary operations.

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- Combine multiple runtime branches into a single malloc_slow check.
- Avoid calling arena_choose / size2index / index2size on fast path.
- A few micro optimizations.
This commit is contained in:
Qi Wang 2015-10-27 15:12:10 -07:00 • committed by Jason Evans
parent 710ca112e3
commit f4a0f32d34
11 changed files with 357 additions and 214 deletions
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26
src/arena.c
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@ -1990,11 +1990,10 @@ arena_tcache_fill_small(arena_t *arena, tcache_bin_t *tbin, szind_t binind,
/*
* OOM. tbin->avail isn't yet filled down to its first
* element, so the successful allocations (if any) must
* be moved to the base of tbin->avail before bailing
* out.
* be moved just before tbin->avail before bailing out.
*/
if (i > 0) {
memmove(tbin->avail, &tbin->avail[nfill - i],
memmove(tbin->avail - i, tbin->avail - nfill,
i * sizeof(void *));
}
break;
@ -2004,7 +2003,7 @@ arena_tcache_fill_small(arena_t *arena, tcache_bin_t *tbin, szind_t binind,
true);
}
/* Insert such that low regions get used first. */
tbin->avail[nfill - 1 - i] = ptr;
*(tbin->avail - nfill + i) = ptr;
}
if (config_stats) {
bin->stats.nmalloc += i;
@ -2125,14 +2124,12 @@ arena_quarantine_junk_small(void *ptr, size_t usize)
}
void *
arena_malloc_small(arena_t *arena, size_t size, bool zero)
arena_malloc_small(arena_t *arena, size_t size, szind_t binind, bool zero)
{
void *ret;
arena_bin_t *bin;
arena_run_t *run;
szind_t binind;
binind = size2index(size);
assert(binind < NBINS);
bin = &arena->bins[binind];
size = index2size(binind);
@ -2179,7 +2176,7 @@ arena_malloc_small(arena_t *arena, size_t size, bool zero)
}
void *
arena_malloc_large(arena_t *arena, size_t size, bool zero)
arena_malloc_large(arena_t *arena, size_t size, szind_t binind, bool zero)
{
void *ret;
size_t usize;
@ -2189,7 +2186,7 @@ arena_malloc_large(arena_t *arena, size_t size, bool zero)
UNUSED bool idump;
/* Large allocation. */
usize = s2u(size);
usize = index2size(binind);
malloc_mutex_lock(&arena->lock);
if (config_cache_oblivious) {
uint64_t r;
@ -2214,7 +2211,7 @@ arena_malloc_large(arena_t *arena, size_t size, bool zero)
ret = (void *)((uintptr_t)arena_miscelm_to_rpages(miscelm) +
random_offset);
if (config_stats) {
szind_t index = size2index(usize) - NBINS;
szind_t index = binind - NBINS;
arena->stats.nmalloc_large++;
arena->stats.nrequests_large++;
@ -2336,7 +2333,8 @@ arena_palloc(tsd_t *tsd, arena_t *arena, size_t usize, size_t alignment,
if (usize <= SMALL_MAXCLASS && (alignment < PAGE || (alignment == PAGE
&& (usize & PAGE_MASK) == 0))) {
/* Small; alignment doesn't require special run placement. */
ret = arena_malloc(tsd, arena, usize, zero, tcache);
ret = arena_malloc(tsd, arena, usize, size2index(usize), zero,
tcache, true);
} else if (usize <= large_maxclass && alignment <= PAGE) {
/*
* Large; alignment doesn't require special run placement.
@ -2344,7 +2342,8 @@ arena_palloc(tsd_t *tsd, arena_t *arena, size_t usize, size_t alignment,
* the base of the run, so do some bit manipulation to retrieve
* the base.
*/
ret = arena_malloc(tsd, arena, usize, zero, tcache);
ret = arena_malloc(tsd, arena, usize, size2index(usize), zero,
tcache, true);
if (config_cache_oblivious)
ret = (void *)((uintptr_t)ret & ~PAGE_MASK);
} else {
@ -2823,7 +2822,8 @@ arena_ralloc_move_helper(tsd_t *tsd, arena_t *arena, size_t usize,
{
if (alignment == 0)
return (arena_malloc(tsd, arena, usize, zero, tcache));
return (arena_malloc(tsd, arena, usize, size2index(usize), zero,
tcache, true));
usize = sa2u(usize, alignment);
if (usize == 0)
return (NULL);