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Use a for-loop to fulfill flush requests that are larger than CACHE_BIN_NFLUSH_BATCH_MAX items

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This commit is contained in:
Shirui Cheng
2024-07-18 17:33:07 -07:00
committed by Qi Wang
parent 48f66cf4a2
commit 47c9bcd402
2 changed files with 39 additions and 16 deletions
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8
include/jemalloc/internal/cache_bin.h
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@@ -600,6 +600,14 @@ cache_bin_nitems_get_remote(cache_bin_t *bin, cache_bin_sz_t *ncached,
*/ */
} }
/*
* Limit how many items can be flushed in a batch (Which is the upper bound
* for the nflush parameter in tcache_bin_flush_impl()).
* This is to avoid stack overflow when we do batch edata look up, which
* reserves a nflush * sizeof(emap_batch_lookup_result_t) stack variable.
*/
#define CACHE_BIN_NFLUSH_BATCH_MAX (VARIABLE_ARRAY_SIZE_MAX >> LG_SIZEOF_PTR)
/* /*
* Filling and flushing are done in batch, on arrays of void *s. For filling, * Filling and flushing are done in batch, on arrays of void *s. For filling,
* the arrays go forward, and can be accessed with ordinary array arithmetic. * the arrays go forward, and can be accessed with ordinary array arithmetic.

47
src/tcache.c
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@@ -712,22 +712,37 @@ tcache_bin_flush_impl_large(tsd_t *tsd, tcache_t *tcache, cache_bin_t *cache_bin
JEMALLOC_ALWAYS_INLINE void JEMALLOC_ALWAYS_INLINE void
tcache_bin_flush_impl(tsd_t *tsd, tcache_t *tcache, cache_bin_t *cache_bin, tcache_bin_flush_impl(tsd_t *tsd, tcache_t *tcache, cache_bin_t *cache_bin,
szind_t binind, cache_bin_ptr_array_t *ptrs, unsigned nflush, bool small) { szind_t binind, cache_bin_ptr_array_t *ptrs, unsigned nflush, bool small) {
/* assert(ptrs != NULL && ptrs->ptr != NULL);
* The small/large flush logic is very similar; you might conclude that unsigned nflush_batch, nflushed = 0;
* it's a good opportunity to share code. We've tried this, and by and cache_bin_ptr_array_t ptrs_batch;
* large found this to obscure more than it helps; there are so many do {
* fiddly bits around things like stats handling, precisely when and nflush_batch = nflush - nflushed;
* which mutexes are acquired, etc., that almost all code ends up being if (nflush_batch > CACHE_BIN_NFLUSH_BATCH_MAX) {
* gated behind 'if (small) { ... } else { ... }'. Even though the nflush_batch = CACHE_BIN_NFLUSH_BATCH_MAX;
* '...' is morally equivalent, the code itself needs slight tweaks. }
*/ assert(nflush_batch <= CACHE_BIN_NFLUSH_BATCH_MAX);
if (small) { (&ptrs_batch)->n = (cache_bin_sz_t)nflush_batch;
tcache_bin_flush_impl_small(tsd, tcache, cache_bin, binind, (&ptrs_batch)->ptr = ptrs->ptr + nflushed;
ptrs, nflush); /*
} else { * The small/large flush logic is very similar; you might conclude that
tcache_bin_flush_impl_large(tsd, tcache, cache_bin, binind, * it's a good opportunity to share code. We've tried this, and by and
ptrs, nflush); * large found this to obscure more than it helps; there are so many
} * fiddly bits around things like stats handling, precisely when and
* which mutexes are acquired, etc., that almost all code ends up being
* gated behind 'if (small) { ... } else { ... }'. Even though the
* '...' is morally equivalent, the code itself needs slight tweaks.
*/
if (small) {
tcache_bin_flush_impl_small(tsd, tcache, cache_bin, binind,
&ptrs_batch, nflush_batch);
} else {
tcache_bin_flush_impl_large(tsd, tcache, cache_bin, binind,
&ptrs_batch, nflush_batch);
}
nflushed += nflush_batch;
} while (nflushed < nflush);
assert(nflush == nflushed);
assert((ptrs->ptr + nflush) == ((&ptrs_batch)->ptr + nflush_batch));
} }
JEMALLOC_ALWAYS_INLINE void JEMALLOC_ALWAYS_INLINE void