Impose a minimum tcache count for small size classes.

Now that small allocation runs have fewer regions due to run metadata
residing in chunk headers, an explicit minimum tcache count is needed to
make sure that tcache adequately amortizes synchronization overhead.
This commit is contained in:
Jason Evans 2015-05-19 17:47:16 -07:00
parent 6591ff09d8
commit 836bbe9951
2 changed files with 10 additions and 1 deletions

View File

@ -16,6 +16,11 @@ typedef struct tcaches_s tcaches_t;
#define TCACHE_STATE_PURGATORY ((tcache_t *)(uintptr_t)3) #define TCACHE_STATE_PURGATORY ((tcache_t *)(uintptr_t)3)
#define TCACHE_STATE_MAX TCACHE_STATE_PURGATORY #define TCACHE_STATE_MAX TCACHE_STATE_PURGATORY
/*
* Absolute minimum number of cache slots for each small bin.
*/
#define TCACHE_NSLOTS_SMALL_MIN 20
/* /*
* Absolute maximum number of cache slots for each small bin in the thread * Absolute maximum number of cache slots for each small bin in the thread
* cache. This is an additional constraint beyond that imposed as: twice the * cache. This is an additional constraint beyond that imposed as: twice the

View File

@ -515,7 +515,11 @@ tcache_boot(void)
return (true); return (true);
stack_nelms = 0; stack_nelms = 0;
for (i = 0; i < NBINS; i++) { for (i = 0; i < NBINS; i++) {
if ((arena_bin_info[i].nregs << 1) <= TCACHE_NSLOTS_SMALL_MAX) { if ((arena_bin_info[i].nregs << 1) <= TCACHE_NSLOTS_SMALL_MIN) {
tcache_bin_info[i].ncached_max =
TCACHE_NSLOTS_SMALL_MIN;
} else if ((arena_bin_info[i].nregs << 1) <=
TCACHE_NSLOTS_SMALL_MAX) {
tcache_bin_info[i].ncached_max = tcache_bin_info[i].ncached_max =
(arena_bin_info[i].nregs << 1); (arena_bin_info[i].nregs << 1);
} else { } else {