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Bin: Move stats closer to the mutex.

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This is a slight cache locality optimization.
This commit is contained in:
David Goldblatt 2021-02-01 12:03:11 -08:00 committed by David Goldblatt
parent c259323ab3
commit 20140629b4
2 changed files with 13 additions and 3 deletions
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9
include/jemalloc/internal/bin.h
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@ -16,6 +16,12 @@ struct bin_s {
/* All operations on bin_t fields require lock ownership. */ /* All operations on bin_t fields require lock ownership. */
malloc_mutex_t lock; malloc_mutex_t lock;
/*
* Bin statistics. These get touched every time the lock is acquired,
* so put them close by in the hopes of getting some cache locality.
*/
bin_stats_t stats;
/* /*
* Current slab being used to service allocations of this bin's size * Current slab being used to service allocations of this bin's size
* class. slabcur is independent of slabs_{nonfull,full}; whenever * class. slabcur is independent of slabs_{nonfull,full}; whenever
@ -33,9 +39,6 @@ struct bin_s {
/* List used to track full slabs. */ /* List used to track full slabs. */
edata_list_active_t slabs_full; edata_list_active_t slabs_full;
/* Bin statistics. */
bin_stats_t stats;
}; };
/* A set of sharded bins of the same size class. */ /* A set of sharded bins of the same size class. */

7
src/tcache.c
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@ -347,6 +347,13 @@ tcache_bin_flush_impl(tsd_t *tsd, tcache_t *tcache, cache_bin_t *cache_bin,
cur_bin = arena_get_bin(cur_arena, binind, cur_bin = arena_get_bin(cur_arena, binind,
cur_binshard); cur_binshard);
assert(cur_binshard < bin_infos[binind].n_shards); assert(cur_binshard < bin_infos[binind].n_shards);
/*
* If you're looking at profiles, you might think this
* is a good place to prefetch the bin stats, which are
* often a cache miss. This turns out not to be
* helpful on the workloads we've looked at, with moving
* the bin stats next to the lock seeming to do better.
*/
} }
if (small) { if (small) {