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Allow opt.tcache_max to accept small size classes.

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Previously all the small size classes were cached.  However this has downsides
-- particularly when page size is greater than 4K (e.g. iOS), which will result
in much higher SMALL_MAXCLASS.

This change allows tcache_max to be set to lower values, to better control
resources taken by tcache.
This commit is contained in:
Qi Wang
2020-10-21 19:47:57 -07:00
committed by Qi Wang
parent ea32060f9c
commit bf72188f80
10 changed files with 265 additions and 33 deletions
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19
src/cache_bin.c
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@@ -24,6 +24,7 @@ cache_bin_info_compute_alloc(cache_bin_info_t *infos, szind_t ninfos,
*/
*size = sizeof(void *) * 2;
for (szind_t i = 0; i < ninfos; i++) {
assert(infos[i].ncached_max > 0);
*size += infos[i].ncached_max * sizeof(void *);
}
@@ -46,26 +47,20 @@ cache_bin_preincrement(cache_bin_info_t *infos, szind_t ninfos, void *alloc,
&computed_alignment);
assert(((uintptr_t)alloc & (computed_alignment - 1)) == 0);
}
/*
* Leave a noticeable mark pattern on the boundaries, in case a bug
* starts leaking those. Make it look like the junk pattern but be
* distinct from it.
*/
uintptr_t preceding_ptr_junk = (uintptr_t)0x7a7a7a7a7a7a7a7aULL;
*(uintptr_t *)((uintptr_t)alloc + *cur_offset) = preceding_ptr_junk;
*(uintptr_t *)((uintptr_t)alloc + *cur_offset) =
cache_bin_preceding_junk;
*cur_offset += sizeof(void *);
}
void
cache_bin_postincrement(cache_bin_info_t *infos, szind_t ninfos, void *alloc,
size_t *cur_offset) {
/* Note: a7 vs. 7a above -- this tells you which pointer leaked. */
uintptr_t trailing_ptr_junk = (uintptr_t)0xa7a7a7a7a7a7a7a7ULL;
*(uintptr_t *)((uintptr_t)alloc + *cur_offset) = trailing_ptr_junk;
*(uintptr_t *)((uintptr_t)alloc + *cur_offset) =
cache_bin_trailing_junk;
*cur_offset += sizeof(void *);
}
void
cache_bin_init(cache_bin_t *bin, cache_bin_info_t *info, void *alloc,
size_t *cur_offset) {
@@ -90,6 +85,8 @@ cache_bin_init(cache_bin_t *bin, cache_bin_info_t *info, void *alloc,
(uint16_t)(uintptr_t) bin->stack_head) == bin_stack_size);
assert(cache_bin_ncached_get(bin, info) == 0);
assert(cache_bin_empty_position_get(bin, info) == empty_position);
assert(bin_stack_size > 0 || empty_position == full_position);
}
bool