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Fix background_thread creation for the oversize_arena.

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Bypassing background thread creation for the oversize_arena used to be an
optimization since that arena had eager purging.  However #2466 changed the
purging policy for the oversize_arena -- specifically it switched to the default
decay time when background_thread is enabled.

This issue is noticable when the number of arenas is low: whenever the total #
of arenas is <= 4 (which is the default max # of background threads), in which
case the purging will be stalled since no background thread is created for the
oversize_arena.
This commit is contained in:
Qi Wang 2024-05-02 12:53:42 -07:00 • committed by Qi Wang
parent 47d69b4eab
commit 8d8379da44
4 changed files with 2 additions and 25 deletions
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1
include/jemalloc/internal/arena_externs.h
View file

@ -103,7 +103,6 @@ void arena_nthreads_inc(arena_t *arena, bool internal);
void arena_nthreads_dec(arena_t *arena, bool internal);
arena_t *arena_new(tsdn_t *tsdn, unsigned ind, const arena_config_t *config);
bool arena_init_huge(arena_t *a0);
bool arena_is_huge(unsigned arena_ind);
arena_t *arena_choose_huge(tsd_t *tsd);
bin_t *arena_bin_choose(tsdn_t *tsdn, arena_t *arena, szind_t binind,
unsigned *binshard);

8
src/arena.c
View file

@ -1867,14 +1867,6 @@ arena_init_huge(arena_t *a0) {
return huge_enabled;
}
bool
arena_is_huge(unsigned arena_ind) {
if (huge_arena_ind == 0) {
return false;
}
return (arena_ind == huge_arena_ind);
}
bool
arena_boot(sc_data_t *sc_data, base_t *base, bool hpa) {
arena_dirty_decay_ms_default_set(opt_dirty_decay_ms);

11
src/ctl.c
View file

@ -2985,17 +2985,6 @@ arena_i_decay_ms_ctl_impl(tsd_t *tsd, const size_t *mib, size_t miblen,
ret = EINVAL;
goto label_return;
}
if (arena_is_huge(arena_ind) && *(ssize_t *)newp > 0) {
/*
* By default the huge arena purges eagerly. If it is
* set to non-zero decay time afterwards, background
* thread might be needed.
*/
if (background_thread_create(tsd, arena_ind)) {
ret = EFAULT;
goto label_return;
}
}
if (arena_decay_ms_set(tsd_tsdn(tsd), arena, state,
*(ssize_t *)newp)) {

7
src/jemalloc.c
View file

@ -430,11 +430,8 @@ arena_new_create_background_thread(tsdn_t *tsdn, unsigned ind) {
if (ind == 0) {
return;
}
/*
* Avoid creating a new background thread just for the huge arena, which
* purges eagerly by default.
*/
if (have_background_thread && !arena_is_huge(ind)) {
if (have_background_thread) {
if (background_thread_create(tsdn_tsd(tsdn), ind)) {
malloc_printf("<jemalloc>: error in background thread "
"creation for arena %u. Abort.\n", ind);