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Allocate tcache stack from base allocator

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When using metadata_thp, allocate tcache bin stacks from base0, which means they
will be placed on huge pages along with other metadata, instead of mixed with
other regular allocations.

In order to do so, modified the base allocator to support limited reuse: freed
tcached stacks (from thread termination) will be returned to base0 and made
available for reuse, but no merging will be attempted since they were bump
allocated out of base blocks. These reused base extents are managed using
separately allocated base edata_t -- they are cached in base->edata_avail when
the extent is all allocated.

One tricky part is, stats updating must be skipped for such reused extents
(since they were accounted for already, and there is no purging for base). This
requires tracking the "if is reused" state explicitly and bypass the stats
updates when allocating from them.
This commit is contained in:
Qi Wang 2023-09-13 21:51:54 -07:00 • committed by Qi Wang
parent a442d9b895
commit 72cfdce718
7 changed files with 202 additions and 27 deletions
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18
src/cache_bin.c
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@ -14,6 +14,17 @@ cache_bin_info_init(cache_bin_info_t *info,
info->ncached_max = (cache_bin_sz_t)ncached_max;
}
bool
cache_bin_stack_use_thp(void) {
/*
* If metadata_thp is enabled, allocating tcache stack from the base
* allocator for efficiency gains. The downside, however, is that base
* allocator never purges freed memory, and may cache a fair amount of
* memory after many threads are terminated and not reused.
*/
return metadata_thp_enabled();
}
void
cache_bin_info_compute_alloc(cache_bin_info_t *infos, szind_t ninfos,
size_t *size, size_t *alignment) {
@ -31,10 +42,11 @@ cache_bin_info_compute_alloc(cache_bin_info_t *infos, szind_t ninfos,
}
/*
* Align to at least PAGE, to minimize the # of TLBs needed by the
* smaller sizes; also helps if the larger sizes don't get used at all.
* When not using THP, align to at least PAGE, to minimize the # of TLBs
* needed by the smaller sizes; also helps if the larger sizes don't get
* used at all.
*/
*alignment = PAGE;
*alignment = cache_bin_stack_use_thp() ? QUANTUM : PAGE;
}
void