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Simplify rtree cache replacement policy.

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To avoid memmove on free() fast path, simplify the cache replacement policy to
only bubble up the cache hit element by 1.
This commit is contained in:
Qi Wang 2017-03-27 11:48:39 -07:00 committed by Qi Wang
parent c6d1819e48
commit af3d737a9a
1 changed files with 11 additions and 14 deletions
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25
include/jemalloc/internal/rtree_inlines.h
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@ -325,30 +325,27 @@ rtree_leaf_elm_lookup(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
if (likely(rtree_ctx->cache[i].leafkey == leafkey)) { \
rtree_leaf_elm_t *leaf = rtree_ctx->cache[i].leaf; \
if (likely(leaf != NULL)) { \
/* Reorder. */ \
memmove(&rtree_ctx->cache[1], \
&rtree_ctx->cache[0], \
sizeof(rtree_ctx_cache_elm_t) * i); \
rtree_ctx->cache[0].leafkey = leafkey; \
rtree_ctx->cache[0].leaf = leaf; \
\
/* Bubble up by one. */ \
if (i > 0) { \
rtree_ctx->cache[i] = \
rtree_ctx->cache[i - 1]; \
rtree_ctx->cache[i - 1].leafkey = \
leafkey; \
rtree_ctx->cache[i - 1].leaf = leaf; \
} \
uintptr_t subkey = rtree_subkey(key, \
RTREE_HEIGHT-1); \
return &leaf[subkey]; \
} \
} \
} while (0)
/* Check the MRU cache entry. */
/* Check the first cache entry. */
RTREE_CACHE_CHECK(0);
/*
* Search the remaining cache elements, and on success move the matching
* element to the front. Unroll the first iteration to avoid calling
* memmove() (the compiler typically optimizes it into raw moves).
* element up by one slot.
*/
if (RTREE_CTX_NCACHE > 1) {
RTREE_CACHE_CHECK(1);
}
for (unsigned i = 2; i < RTREE_CTX_NCACHE; i++) {
for (unsigned i = 1; i < RTREE_CTX_NCACHE; i++) {
RTREE_CACHE_CHECK(i);
}
#undef RTREE_CACHE_CHECK