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Make dss operations lockless.

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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
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8
src/huge.c
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@ -114,7 +114,7 @@ huge_palloc(tsdn_t *tsdn, arena_t *arena, size_t usize, size_t alignment,
#define huge_dalloc_junk JEMALLOC_N(huge_dalloc_junk_impl)
#endif
static void
huge_dalloc_junk(tsdn_t *tsdn, void *ptr, size_t usize)
huge_dalloc_junk(void *ptr, size_t usize)
{
if (config_fill && have_dss && unlikely(opt_junk_free)) {
@ -122,7 +122,7 @@ huge_dalloc_junk(tsdn_t *tsdn, void *ptr, size_t usize)
* Only bother junk filling if the chunk isn't about to be
* unmapped.
*/
if (!config_munmap || (have_dss && chunk_in_dss(tsdn, ptr)))
if (!config_munmap || (have_dss && chunk_in_dss(ptr)))
memset(ptr, JEMALLOC_FREE_JUNK, usize);
}
}
@ -221,7 +221,7 @@ huge_ralloc_no_move_shrink(tsdn_t *tsdn, void *ptr, size_t oldsize,
if (oldsize > usize) {
size_t sdiff = oldsize - usize;
if (config_fill && unlikely(opt_junk_free)) {
huge_dalloc_junk(tsdn, (void *)((uintptr_t)ptr + usize),
huge_dalloc_junk((void *)((uintptr_t)ptr + usize),
sdiff);
post_zeroed = false;
} else {
@ -402,7 +402,7 @@ huge_dalloc(tsdn_t *tsdn, void *ptr)
ql_remove(&arena->huge, node, ql_link);
malloc_mutex_unlock(tsdn, &arena->huge_mtx);
huge_dalloc_junk(tsdn, extent_node_addr_get(node),
huge_dalloc_junk(extent_node_addr_get(node),
extent_node_size_get(node));
arena_chunk_dalloc_huge(tsdn, extent_node_arena_get(node),
extent_node_addr_get(node), extent_node_size_get(node));