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Eset: take opt_lg_max_active_fit as a parameter.

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This breaks its dependence on the global.
This commit is contained in:
David Goldblatt 2020-03-14 09:46:09 -07:00 committed by David Goldblatt
parent 883ab327cc
commit 7bb6e2dc0d
3 changed files with 31 additions and 14 deletions
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2
include/jemalloc/internal/eset.h
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@ -52,6 +52,6 @@ void eset_remove(eset_t *eset, edata_t *edata);
* null if no such item could be found.
*/
edata_t *eset_fit(eset_t *eset, size_t esize, size_t alignment,
bool delay_coalesce);
unsigned lg_max_fit);
#endif /* JEMALLOC_INTERNAL_ESET_H */

29
src/eset.c
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@ -154,9 +154,15 @@ eset_fit_alignment(eset_t *eset, size_t min_size, size_t max_size,
/*
* Do first-fit extent selection, i.e. select the oldest/lowest extent that is
* large enough.
*
* lg_max_fit is the (log of the) maximum ratio between the requested size and
* the returned size that we'll allow. This can reduce fragmentation by
* avoiding reusing and splitting large extents for smaller sizes. In practice,
* it's set to opt_lg_extent_max_active_fit for the dirty eset and SC_PTR_BITS
* for others.
*/
static edata_t *
eset_first_fit(eset_t *eset, size_t size, bool delay_coalesce) {
eset_first_fit(eset_t *eset, size_t size, unsigned lg_max_fit) {
edata_t *ret = NULL;
pszind_t pind = sz_psz2ind(sz_psz_quantize_ceil(size));
@ -178,14 +184,15 @@ eset_first_fit(eset_t *eset, size_t size, bool delay_coalesce) {
assert(!edata_heap_empty(&eset->heaps[i]));
edata_t *edata = edata_heap_first(&eset->heaps[i]);
assert(edata_size_get(edata) >= size);
/*
* In order to reduce fragmentation, avoid reusing and splitting
* large eset for much smaller sizes.
*
* Only do check for dirty eset (delay_coalesce).
*/
if (delay_coalesce &&
(sz_pind2sz(i) >> opt_lg_extent_max_active_fit) > size) {
if (lg_max_fit == SC_PTR_BITS) {
/*
* We'll shift by this below, and shifting out all the
* bits is undefined. Decreasing is safe, since the
* page size is larger than 1 byte.
*/
lg_max_fit = SC_PTR_BITS - 1;
}
if ((sz_pind2sz(i) >> lg_max_fit) > size) {
break;
}
if (ret == NULL || edata_snad_comp(edata, ret) < 0) {
@ -201,14 +208,14 @@ eset_first_fit(eset_t *eset, size_t size, bool delay_coalesce) {
}
edata_t *
eset_fit(eset_t *eset, size_t esize, size_t alignment, bool delay_coalesce) {
eset_fit(eset_t *eset, size_t esize, size_t alignment, unsigned lg_max_fit) {
size_t max_size = esize + PAGE_CEILING(alignment) - PAGE;
/* Beware size_t wrap-around. */
if (max_size < esize) {
return NULL;
}
edata_t *edata = eset_first_fit(eset, max_size, delay_coalesce);
edata_t *edata = eset_first_fit(eset, max_size, lg_max_fit);
if (alignment > PAGE && edata == NULL) {
/*

14
src/extent.c
View File

@ -398,8 +398,18 @@ extent_recycle_extract(tsdn_t *tsdn, pa_shard_t *shard, ehooks_t *ehooks,
emap_unlock_edata(tsdn, &emap_global, unlock_edata);
}
} else {
edata = eset_fit(&ecache->eset, size, alignment,
ecache->delay_coalesce);
/*
* A large extent might be broken up from its original size to
* some small size to satisfy a small request. When that small
* request is freed, though, it won't merge back with the larger
* extent if delayed coalescing is on. The large extent can
* then no longer satify a request for its original size. To
* limit this effect, when delayed coalescing is enabled, we
* put a cap on how big an extent we can split for a request.
*/
unsigned lg_max_fit = ecache->delay_coalesce
? (unsigned)opt_lg_extent_max_active_fit : SC_PTR_BITS;
edata = eset_fit(&ecache->eset, size, alignment, lg_max_fit);
}
if (edata == NULL) {
malloc_mutex_unlock(tsdn, &ecache->mtx);