From 2aa14ce5a1df0f7f74f0826e252c5312824c79bf Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Mon, 19 Dec 2022 17:26:25 +0100 Subject: [PATCH] MINOR: pool: only use opportunistic versions of the swrate_add() functions We don't need to know very accurately how much RAM is needed in a pool, however we must not spend time competing with other threads trying to be the one with the most accurate value. Let's use the "_opportunistic" variants of swrate_add() which will simply cause some updates to be dropped in case of thread contention. This should significantly improve the situation when dealing with many threads and small per-thread caches. Performance gains of up to 1-2% were observed on 48-thread systems thanks to this alone. --- src/pool.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/pool.c b/src/pool.c index df9d06090..610e20cc3 100644 --- a/src/pool.c +++ b/src/pool.c @@ -380,7 +380,7 @@ void *pool_alloc_nocache(struct pool_head *pool) if (!ptr) return NULL; - swrate_add_scaled(&pool->needed_avg, POOL_AVG_SAMPLES, pool->used, POOL_AVG_SAMPLES/4); + swrate_add_scaled_opportunistic(&pool->needed_avg, POOL_AVG_SAMPLES, pool->used, POOL_AVG_SAMPLES/4); _HA_ATOMIC_INC(&pool->used); /* keep track of where the element was allocated from */ @@ -396,7 +396,7 @@ void *pool_alloc_nocache(struct pool_head *pool) void pool_free_nocache(struct pool_head *pool, void *ptr) { _HA_ATOMIC_DEC(&pool->used); - swrate_add(&pool->needed_avg, POOL_AVG_SAMPLES, pool->used); + swrate_add_opportunistic(&pool->needed_avg, POOL_AVG_SAMPLES, pool->used); pool_put_to_os(pool, ptr); } @@ -655,7 +655,7 @@ void pool_put_to_shared_cache(struct pool_head *pool, struct pool_item *item, ui __ha_barrier_atomic_store(); } while (!_HA_ATOMIC_CAS(&pool->free_list, &free_list, item)); __ha_barrier_atomic_store(); - swrate_add(&pool->needed_avg, POOL_AVG_SAMPLES, pool->used); + swrate_add_opportunistic(&pool->needed_avg, POOL_AVG_SAMPLES, pool->used); } /*