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edata_cache: Allow unbounded fast caching.

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The edata_cache_small had a fill/flush heuristic.  In retrospect, this was a
premature optimization; more testing indicates that an unbounded cache is
effectively fine here, and moreover we spend a nontrivial amount of time doing
unnecessary filling/flushing.

As the HPA takes on a larger and larger fraction of all allocations, any
theoretical differences in allocation patterns should shrink.  The HPA is more
efficient with its metadata in general, so it still comes out ahead on metadata
usage anyways.
This commit is contained in:
David Goldblatt
2021-07-23 15:29:43 -07:00
committed by David Goldblatt
parent d93eef2f40
commit 92a1e38f52
5 changed files with 99 additions and 151 deletions
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24
include/jemalloc/internal/edata_cache.h
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@@ -3,15 +3,8 @@
#include "jemalloc/internal/base.h"
/*
* Public for tests. When we go to the fallback when the small cache is empty,
* we grab up to 8 items (grabbing less only if the fallback is exhausted).
* When we exceed 16, we flush. This caps the maximum memory lost per cache to
* 16 * sizeof(edata_t), a max of 2k on architectures where the edata_t is 128
* bytes.
*/
#define EDATA_CACHE_SMALL_MAX 16
#define EDATA_CACHE_SMALL_FILL 8
/* For tests only. */
#define EDATA_CACHE_FAST_FILL 4
/*
* A cache of edata_t structures allocated via base_alloc_edata (as opposed to
@@ -40,18 +33,17 @@ void edata_cache_postfork_child(tsdn_t *tsdn, edata_cache_t *edata_cache);
* synchronization and avoids first-fit strategies.
*/
typedef struct edata_cache_small_s edata_cache_small_t;
struct edata_cache_small_s {
typedef struct edata_cache_fast_s edata_cache_fast_t;
struct edata_cache_fast_s {
edata_list_inactive_t list;
size_t count;
edata_cache_t *fallback;
bool disabled;
};
void edata_cache_small_init(edata_cache_small_t *ecs, edata_cache_t *fallback);
edata_t *edata_cache_small_get(tsdn_t *tsdn, edata_cache_small_t *ecs);
void edata_cache_small_put(tsdn_t *tsdn, edata_cache_small_t *ecs,
void edata_cache_fast_init(edata_cache_fast_t *ecs, edata_cache_t *fallback);
edata_t *edata_cache_fast_get(tsdn_t *tsdn, edata_cache_fast_t *ecs);
void edata_cache_fast_put(tsdn_t *tsdn, edata_cache_fast_t *ecs,
edata_t *edata);
void edata_cache_small_disable(tsdn_t *tsdn, edata_cache_small_t *ecs);
void edata_cache_fast_disable(tsdn_t *tsdn, edata_cache_fast_t *ecs);
#endif /* JEMALLOC_INTERNAL_EDATA_CACHE_H */

2
include/jemalloc/internal/hpa.h
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@@ -102,7 +102,7 @@ struct hpa_shard_s {
* from a pageslab. The pageslab itself comes from the centralized
* allocator, and so will use its edata_cache.
*/
edata_cache_small_t ecs;
edata_cache_fast_t ecf;
psset_t psset;