Make dss operations lockless.

Rather than protecting dss operations with a mutex, use atomic
operations.  This has negligible impact on synchronization overhead
during typical dss allocation, but is a substantial improvement for
chunk_in_dss() and the newly added chunk_dss_mergeable(), which can be
called multiple times during chunk deallocations.

This change also has the advantage of avoiding tsd in deallocation paths
associated with purging, which resolves potential deadlocks during
thread exit due to attempted tsd resurrection.

This resolves #425.
This commit is contained in:
Jason Evans
2016-10-13 12:18:38 -07:00
parent 9737685943
commit e2bcf037d4
11 changed files with 134 additions and 153 deletions

View File

@@ -71,9 +71,6 @@ bool chunk_purge_wrapper(tsdn_t *tsdn, arena_t *arena,
chunk_hooks_t *chunk_hooks, void *chunk, size_t size, size_t offset,
size_t length);
bool chunk_boot(void);
void chunk_prefork(tsdn_t *tsdn);
void chunk_postfork_parent(tsdn_t *tsdn);
void chunk_postfork_child(tsdn_t *tsdn);
#endif /* JEMALLOC_H_EXTERNS */
/******************************************************************************/

View File

@@ -21,15 +21,13 @@ extern const char *dss_prec_names[];
/******************************************************************************/
#ifdef JEMALLOC_H_EXTERNS
dss_prec_t chunk_dss_prec_get(tsdn_t *tsdn);
bool chunk_dss_prec_set(tsdn_t *tsdn, dss_prec_t dss_prec);
dss_prec_t chunk_dss_prec_get(void);
bool chunk_dss_prec_set(dss_prec_t dss_prec);
void *chunk_alloc_dss(tsdn_t *tsdn, arena_t *arena, void *new_addr,
size_t size, size_t alignment, bool *zero, bool *commit);
bool chunk_in_dss(tsdn_t *tsdn, void *chunk);
bool chunk_dss_boot(void);
void chunk_dss_prefork(tsdn_t *tsdn);
void chunk_dss_postfork_parent(tsdn_t *tsdn);
void chunk_dss_postfork_child(tsdn_t *tsdn);
bool chunk_in_dss(void *chunk);
bool chunk_dss_mergeable(void *chunk_a, void *chunk_b);
void chunk_dss_boot(void);
#endif /* JEMALLOC_H_EXTERNS */
/******************************************************************************/

View File

@@ -17,7 +17,7 @@ bool huge_ralloc_no_move(tsdn_t *tsdn, void *ptr, size_t oldsize,
void *huge_ralloc(tsd_t *tsd, arena_t *arena, void *ptr, size_t oldsize,
size_t usize, size_t alignment, bool zero, tcache_t *tcache);
#ifdef JEMALLOC_JET
typedef void (huge_dalloc_junk_t)(tsdn_t *, void *, size_t);
typedef void (huge_dalloc_junk_t)(void *, size_t);
extern huge_dalloc_junk_t *huge_dalloc_junk;
#endif
void huge_dalloc(tsdn_t *tsdn, void *ptr);

View File

@@ -167,20 +167,15 @@ chunk_dalloc_mmap
chunk_dalloc_wrapper
chunk_deregister
chunk_dss_boot
chunk_dss_postfork_child
chunk_dss_postfork_parent
chunk_dss_mergeable
chunk_dss_prec_get
chunk_dss_prec_set
chunk_dss_prefork
chunk_hooks_default
chunk_hooks_get
chunk_hooks_set
chunk_in_dss
chunk_lookup
chunk_npages
chunk_postfork_child
chunk_postfork_parent
chunk_prefork
chunk_purge_wrapper
chunk_register
chunks_rtree