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| author | Michael Cahill <michael.cahill@mongodb.com> | 2017-07-10 23:33:31 -0400 |
|---|---|---|
| committer | Alex Gorrod <alexander.gorrod@mongodb.com> | 2017-09-07 08:52:53 +1000 |
| commit | 31af5d70a87cf1d99c7275bc8bc01d29e2cb0d2a (patch) | |
| tree | ea27c47def1002f9d85e516fa8d5caf16d8695c9 | |
| parent | 3579adf6c8b96d26898af9fe3cc5eb9677f75632 (diff) | |
| download | mongodb-3.4.9.tar.gz | |
WT-3329 Visit trees using a tiny fraction of cache. (#3442)mongodb-3.4.9
For workloads where no tree takes up a large enough fraction of cache,
we were using a randomized approach to deciding when eviction should
visit trees. That led to slow performance for workloads with uniform
updates over thousands of trees.
(cherry picked from commit 2f1ec98512010f6c92bf27a41180e3c8704b54c8)
Signed-off-by: Alex Gorrod <alexander.gorrod@mongodb.com>
| -rw-r--r-- | src/evict/evict_lru.c | 26 | ||||
| -rw-r--r-- | src/include/extern.h | 1 | ||||
| -rw-r--r-- | src/support/rand.c | 12 |
3 files changed, 8 insertions, 31 deletions
diff --git a/src/evict/evict_lru.c b/src/evict/evict_lru.c index cc3c5a5c824..fdf68841b85 100644 --- a/src/evict/evict_lru.c +++ b/src/evict/evict_lru.c @@ -1647,26 +1647,16 @@ __evict_walk_file(WT_SESSION_IMPL *session, QUEUE_FILLS_PER_PASS; /* - * Randomly walk trees with a small fraction of the cache in case there - * are so many trees that none of them use enough of the cache to be - * allocated slots. - * - * The chance of walking a tree is equal to the chance that a random - * byte in cache belongs to the tree, weighted by how many times we - * want to fill queues during a pass through all the trees in cache. + * Walk trees with a small fraction of the cache in case there are so + * many trees that none of them use enough of the cache to be allocated + * slots. Only skip a tree if it has no bytes of interest. */ if (target_pages == 0) { - if (F_ISSET(cache, WT_CACHE_EVICT_CLEAN)) { - btree_inuse = __wt_btree_bytes_evictable(session); - cache_inuse = __wt_cache_bytes_inuse(cache); - } else { - btree_inuse = __wt_btree_dirty_leaf_inuse(session); - cache_inuse = __wt_cache_dirty_leaf_inuse(cache); - } - if (btree_inuse == 0 || cache_inuse == 0) - return (0); - if (__wt_random64(&session->rnd) % cache_inuse > - btree_inuse * QUEUE_FILLS_PER_PASS) + btree_inuse = F_ISSET(cache, WT_CACHE_EVICT_CLEAN) ? + __wt_btree_bytes_evictable(session) : + __wt_btree_dirty_leaf_inuse(session); + + if (btree_inuse == 0) return (0); } diff --git a/src/include/extern.h b/src/include/extern.h index dfd2d03707f..12233c0247a 100644 --- a/src/include/extern.h +++ b/src/include/extern.h @@ -692,7 +692,6 @@ extern uint32_t __wt_rduppo2(uint32_t n, uint32_t po2); extern void __wt_random_init(WT_RAND_STATE volatile *rnd_state) WT_GCC_FUNC_DECL_ATTRIBUTE((visibility("default"))); extern void __wt_random_init_seed( WT_SESSION_IMPL *session, WT_RAND_STATE volatile *rnd_state) WT_GCC_FUNC_DECL_ATTRIBUTE((visibility("default"))); extern uint32_t __wt_random(WT_RAND_STATE volatile *rnd_state) WT_GCC_FUNC_DECL_ATTRIBUTE((visibility("default"))); -extern uint64_t __wt_random64(WT_RAND_STATE volatile *rnd_state) WT_GCC_FUNC_DECL_ATTRIBUTE((visibility("default"))); extern int __wt_buf_grow_worker(WT_SESSION_IMPL *session, WT_ITEM *buf, size_t size) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result)); extern int __wt_buf_fmt(WT_SESSION_IMPL *session, WT_ITEM *buf, const char *fmt, ...) WT_GCC_FUNC_DECL_ATTRIBUTE((format (printf, 3, 4))) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result)); extern int __wt_buf_catfmt(WT_SESSION_IMPL *session, WT_ITEM *buf, const char *fmt, ...) WT_GCC_FUNC_DECL_ATTRIBUTE((format (printf, 3, 4))) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result)); diff --git a/src/support/rand.c b/src/support/rand.c index 4fae43edc8e..a5b229b9abc 100644 --- a/src/support/rand.c +++ b/src/support/rand.c @@ -120,15 +120,3 @@ __wt_random(WT_RAND_STATE volatile * rnd_state) return ((z << 16) + (w & 65535)); } - -/* - * __wt_random64 -- - * Return a 64-bit pseudo-random number. - */ -uint64_t -__wt_random64(WT_RAND_STATE volatile * rnd_state) - WT_GCC_FUNC_ATTRIBUTE((visibility("default"))) -{ - return (((uint64_t)__wt_random(rnd_state) << 32) + - __wt_random(rnd_state)); -} |