Use exponential series to size extents.
If virtual memory is retained, allocate extents such that their sizes form an exponentially growing series. This limits the number of disjoint virtual memory ranges so that extent merging can be effective even if multiple arenas' extent allocation requests are highly interleaved. This resolves #462.
This commit is contained in:
Jason Evans
parent
c1baa0a9b7
commit
411697adcd
@ -232,6 +232,15 @@ struct arena_s {
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void *extent_hooks_pun;
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};
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/*
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* Next extent size class in a growing series to use when satisfying a
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* request via the extent hooks (only if !config_munmap). This limits
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* the number of disjoint virtual memory ranges so that extent merging
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* can be effective even if multiple arenas' extent allocation requests
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* are highly interleaved.
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*/
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pszind_t extent_grow_next;
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/* Cache of extent structures that were allocated via base_alloc(). */
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ql_head(extent_t) extent_cache;
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malloc_mutex_t extent_cache_mtx;
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@ -1686,6 +1686,9 @@ arena_new(tsdn_t *tsdn, unsigned ind)
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arena->extent_hooks = (extent_hooks_t *)&extent_hooks_default;
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if (!config_munmap)
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arena->extent_grow_next = psz2ind(HUGEPAGE);
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ql_new(&arena->extent_cache);
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if (malloc_mutex_init(&arena->extent_cache_mtx, "arena_extent_cache",
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WITNESS_RANK_ARENA_EXTENT_CACHE))
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219
src/extent.c
219
src/extent.c
@ -265,6 +265,41 @@ extent_interior_register(tsdn_t *tsdn, rtree_ctx_t *rtree_ctx,
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}
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}
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static void
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extent_gprof_add(tsdn_t *tsdn, const extent_t *extent)
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{
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cassert(config_prof);
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if (opt_prof && extent_active_get(extent)) {
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size_t nadd = extent_size_get(extent) >> LG_PAGE;
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size_t cur = atomic_add_zu(&curpages, nadd);
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size_t high = atomic_read_zu(&highpages);
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while (cur > high && atomic_cas_zu(&highpages, high, cur)) {
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/*
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* Don't refresh cur, because it may have decreased
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* since this thread lost the highpages update race.
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*/
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high = atomic_read_zu(&highpages);
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}
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if (cur > high && prof_gdump_get_unlocked())
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prof_gdump(tsdn);
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}
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}
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static void
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extent_gprof_sub(tsdn_t *tsdn, const extent_t *extent)
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{
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cassert(config_prof);
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if (opt_prof && extent_active_get(extent)) {
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size_t nsub = extent_size_get(extent) >> LG_PAGE;
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assert(atomic_read_zu(&curpages) >= nsub);
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atomic_sub_zu(&curpages, nsub);
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}
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}
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static bool
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extent_register(tsdn_t *tsdn, const extent_t *extent)
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{
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@ -280,20 +315,8 @@ extent_register(tsdn_t *tsdn, const extent_t *extent)
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extent_interior_register(tsdn, rtree_ctx, extent);
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extent_rtree_release(tsdn, elm_a, elm_b);
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if (config_prof && opt_prof && extent_active_get(extent)) {
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size_t nadd = extent_size_get(extent) >> LG_PAGE;
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size_t cur = atomic_add_zu(&curpages, nadd);
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size_t high = atomic_read_zu(&highpages);
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while (cur > high && atomic_cas_zu(&highpages, high, cur)) {
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/*
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* Don't refresh cur, because it may have decreased
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* since this thread lost the highpages update race.
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*/
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high = atomic_read_zu(&highpages);
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}
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if (cur > high && prof_gdump_get_unlocked())
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prof_gdump(tsdn);
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}
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if (config_prof)
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extent_gprof_add(tsdn, extent);
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return (false);
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}
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@ -336,11 +359,8 @@ extent_deregister(tsdn_t *tsdn, extent_t *extent)
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}
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extent_rtree_release(tsdn, elm_a, elm_b);
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if (config_prof && opt_prof && extent_active_get(extent)) {
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size_t nsub = extent_size_get(extent) >> LG_PAGE;
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assert(atomic_read_zu(&curpages) >= nsub);
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atomic_sub_zu(&curpages, nsub);
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}
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if (config_prof)
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extent_gprof_sub(tsdn, extent);
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}
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/*
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@ -507,14 +527,16 @@ extent_recycle(tsdn_t *tsdn, arena_t *arena, extent_hooks_t **r_extent_hooks,
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extent_usize_set(extent, usize);
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}
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if (commit && !extent_committed_get(extent) &&
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extent_commit_wrapper(tsdn, arena, r_extent_hooks, extent, 0,
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extent_size_get(extent))) {
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if (!locked)
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malloc_mutex_unlock(tsdn, &arena->extents_mtx);
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extent_record(tsdn, arena, r_extent_hooks, extent_heaps, cache,
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extent);
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return (NULL);
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if (*commit && !extent_committed_get(extent)) {
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if (extent_commit_wrapper(tsdn, arena, r_extent_hooks, extent,
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0, extent_size_get(extent))) {
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if (!locked)
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malloc_mutex_unlock(tsdn, &arena->extents_mtx);
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extent_record(tsdn, arena, r_extent_hooks, extent_heaps,
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cache, extent);
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return (NULL);
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}
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extent_zeroed_set(extent, true);
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}
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if (pad != 0)
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@ -591,8 +613,6 @@ extent_alloc_cache_impl(tsdn_t *tsdn, arena_t *arena,
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extent = extent_recycle(tsdn, arena, r_extent_hooks,
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arena->extents_cached, locked, true, new_addr, usize, pad,
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alignment, zero, commit, slab);
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if (extent == NULL)
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return (NULL);
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return (extent);
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}
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@ -626,9 +646,6 @@ extent_alloc_default_impl(tsdn_t *tsdn, arena_t *arena, void *new_addr,
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ret = extent_alloc_core(tsdn, arena, new_addr, size, alignment, zero,
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commit, arena->dss_prec);
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if (ret == NULL)
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return (NULL);
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return (ret);
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}
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@ -653,6 +670,136 @@ extent_alloc_default(extent_hooks_t *extent_hooks, void *new_addr, size_t size,
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alignment, zero, commit));
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}
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static void
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extent_retain(tsdn_t *tsdn, arena_t *arena, extent_hooks_t **r_extent_hooks,
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extent_t *extent)
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{
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if (config_stats)
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arena->stats.retained += extent_size_get(extent);
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extent_record(tsdn, arena, r_extent_hooks, arena->extents_retained,
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false, extent);
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}
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/*
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* If virtual memory is retained, create increasingly larger extents from which
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* to split requested extents in order to limit the total number of disjoint
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* virtual memory ranges retained by each arena.
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*/
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static extent_t *
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extent_grow_retained(tsdn_t *tsdn, arena_t *arena,
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extent_hooks_t **r_extent_hooks, void *new_addr, size_t usize, size_t pad,
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size_t alignment, bool *zero, bool *commit, bool slab)
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{
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extent_t *extent;
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void *ptr;
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size_t size, alloc_size, alloc_size_min, leadsize, trailsize;
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bool zeroed, committed;
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/*
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* Check whether the next extent size in the series would be large
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* enough to satisfy this request. If no, just bail, so that e.g. a
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* series of unsatisfiable allocation requests doesn't cause unused
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* extent creation as a side effect.
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*/
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size = usize + pad;
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alloc_size = pind2sz(arena->extent_grow_next);
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alloc_size_min = size + PAGE_CEILING(alignment) - PAGE;
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/* Beware size_t wrap-around. */
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if (alloc_size_min < usize)
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return (NULL);
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if (alloc_size < alloc_size_min)
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return (NULL);
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extent = extent_alloc(tsdn, arena);
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if (extent == NULL)
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return (NULL);
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zeroed = false;
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committed = false;
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ptr = extent_alloc_core(tsdn, arena, new_addr, alloc_size, PAGE,
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&zeroed, &committed, arena->dss_prec);
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extent_init(extent, arena, ptr, alloc_size, alloc_size,
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arena_extent_sn_next(arena), false, zeroed, committed, false);
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if (ptr == NULL || extent_register(tsdn, extent)) {
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extent_dalloc(tsdn, arena, extent);
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return (NULL);
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}
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/*
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* Set the extent as active *after registration so that no gprof-related
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* accounting occurs during registration.
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*/
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extent_active_set(extent, true);
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leadsize = ALIGNMENT_CEILING((uintptr_t)ptr, PAGE_CEILING(alignment)) -
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(uintptr_t)ptr;
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assert(new_addr == NULL || leadsize == 0);
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assert(alloc_size >= leadsize + size);
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trailsize = alloc_size - leadsize - size;
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if (extent_zeroed_get(extent))
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*zero = true;
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if (extent_committed_get(extent))
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*commit = true;
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/* Split the lead. */
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if (leadsize != 0) {
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extent_t *lead = extent;
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extent = extent_split_wrapper(tsdn, arena, r_extent_hooks, lead,
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leadsize, leadsize, size + trailsize, usize + trailsize);
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if (extent == NULL) {
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extent_deregister(tsdn, lead);
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extent_leak(tsdn, arena, r_extent_hooks, false, lead);
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return (NULL);
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}
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extent_retain(tsdn, arena, r_extent_hooks, lead);
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}
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/* Split the trail. */
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if (trailsize != 0) {
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extent_t *trail = extent_split_wrapper(tsdn, arena,
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r_extent_hooks, extent, size, usize, trailsize, trailsize);
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if (trail == NULL) {
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extent_deregister(tsdn, extent);
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extent_leak(tsdn, arena, r_extent_hooks, false, extent);
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return (NULL);
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}
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extent_retain(tsdn, arena, r_extent_hooks, trail);
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} else if (leadsize == 0) {
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/*
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* Splitting causes usize to be set as a side effect, but no
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* splitting occurred.
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*/
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extent_usize_set(extent, usize);
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}
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if (*commit && !extent_committed_get(extent)) {
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if (extent_commit_wrapper(tsdn, arena, r_extent_hooks, extent,
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0, extent_size_get(extent))) {
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extent_retain(tsdn, arena, r_extent_hooks, extent);
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return (NULL);
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}
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extent_zeroed_set(extent, true);
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}
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if (config_prof) {
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/* Adjust gprof stats now that extent is final size. */
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extent_gprof_add(tsdn, extent);
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}
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if (pad != 0)
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extent_addr_randomize(tsdn, extent, alignment);
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if (slab) {
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rtree_ctx_t rtree_ctx_fallback;
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rtree_ctx_t *rtree_ctx = tsdn_rtree_ctx(tsdn,
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&rtree_ctx_fallback);
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extent_slab_set(extent, true);
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extent_interior_register(tsdn, rtree_ctx, extent);
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}
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if (*zero && !extent_zeroed_get(extent))
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memset(extent_addr_get(extent), 0, extent_usize_get(extent));
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if (arena->extent_grow_next + 1 < NPSIZES)
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arena->extent_grow_next++;
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return (extent);
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}
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static extent_t *
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extent_alloc_retained(tsdn_t *tsdn, arena_t *arena,
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extent_hooks_t **r_extent_hooks, void *new_addr, size_t usize, size_t pad,
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@ -669,6 +816,12 @@ extent_alloc_retained(tsdn_t *tsdn, arena_t *arena,
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if (extent != NULL && config_stats) {
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size_t size = usize + pad;
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arena->stats.retained -= size;
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if (config_prof)
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extent_gprof_add(tsdn, extent);
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}
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if (!config_munmap && extent == NULL) {
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extent = extent_grow_retained(tsdn, arena, r_extent_hooks,
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new_addr, usize, pad, alignment, zero, commit, slab);
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}
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return (extent);
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@ -909,6 +1062,8 @@ extent_dalloc_wrapper(tsdn_t *tsdn, arena_t *arena,
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if (config_stats)
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arena->stats.retained += extent_size_get(extent);
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if (config_prof)
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extent_gprof_sub(tsdn, extent);
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extent_record(tsdn, arena, r_extent_hooks, arena->extents_retained,
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false, extent);
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