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Bypass extent_dalloc when retain is enabled.

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When retain is enabled, the default dalloc hook does nothing (since we avoid
munmap).  But the overhead preparing the call is high, specifically the extent
de-register and re-register involve locking and extent / rtree modifications.
Bypass the call with retain in this diff.
This commit is contained in:
Qi Wang 2018-10-31 14:54:53 -07:00 committed by Qi Wang
parent 50b473c883
commit 8dabf81df1
1 changed files with 18 additions and 8 deletions
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18
src/extent.c
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@ -1695,6 +1695,12 @@ extent_dalloc_gap(tsdn_t *tsdn, arena_t *arena, extent_t *extent) {
extent_dalloc_wrapper(tsdn, arena, &extent_hooks, extent); extent_dalloc_wrapper(tsdn, arena, &extent_hooks, extent);
} }
static bool
extent_may_dalloc(void) {
/* With retain enabled, the default dalloc always fails. */
return !opt_retain;
}
static bool static bool
extent_dalloc_default_impl(void *addr, size_t size) { extent_dalloc_default_impl(void *addr, size_t size) {
if (!have_dss || !extent_in_dss(addr)) { if (!have_dss || !extent_in_dss(addr)) {
@ -1750,16 +1756,20 @@ extent_dalloc_wrapper(tsdn_t *tsdn, arena_t *arena,
witness_assert_depth_to_rank(tsdn_witness_tsdp_get(tsdn), witness_assert_depth_to_rank(tsdn_witness_tsdp_get(tsdn),
WITNESS_RANK_CORE, 0); WITNESS_RANK_CORE, 0);
/* Avoid calling the default extent_dalloc unless have to. */
if (*r_extent_hooks != &extent_hooks_default || extent_may_dalloc()) {
/* /*
* Deregister first to avoid a race with other allocating threads, and * Deregister first to avoid a race with other allocating
* reregister if deallocation fails. * threads, and reregister if deallocation fails.
*/ */
extent_deregister(tsdn, extent); extent_deregister(tsdn, extent);
if (!extent_dalloc_wrapper_try(tsdn, arena, r_extent_hooks, extent)) { if (!extent_dalloc_wrapper_try(tsdn, arena, r_extent_hooks,
extent)) {
return; return;
} }
extent_reregister(tsdn, extent); extent_reregister(tsdn, extent);
}
if (*r_extent_hooks != &extent_hooks_default) { if (*r_extent_hooks != &extent_hooks_default) {
extent_hook_pre_reentrancy(tsdn, arena); extent_hook_pre_reentrancy(tsdn, arena);
} }