From 4699d76d19f1ff4a59c16c10b2aedab6f5054a73 Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Thu, 23 Jul 2015 13:45:31 -0700 Subject: Remove skc_ref from alloc/free paths As described in spl_kmem_cache_destroy() the ->skc_ref count was added to address the case of a cache reap or grow racing with a destroy. They are not strictly needed in the alloc/free paths because consumers of the cache are responsible for not using it while it's being destroyed. Removing this code is desirable because there is some evidence that contention on this atomic negative impacts performance on large-scale NUMA systems. Signed-off-by: Brian Behlendorf Signed-off-by: Tim Chase Issue #463 --- module/spl/spl-kmem-cache.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) (limited to 'module/spl') diff --git a/module/spl/spl-kmem-cache.c b/module/spl/spl-kmem-cache.c index 112d0f876..0417f9d0b 100644 --- a/module/spl/spl-kmem-cache.c +++ b/module/spl/spl-kmem-cache.c @@ -1403,8 +1403,6 @@ spl_kmem_cache_alloc(spl_kmem_cache_t *skc, int flags) ASSERT(skc->skc_magic == SKC_MAGIC); ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags)); - atomic_inc(&skc->skc_ref); - /* * Allocate directly from a Linux slab. All optimizations are left * to the underlying cache we only need to guarantee that KM_SLEEP @@ -1457,8 +1455,6 @@ ret: prefetchw(obj); } - atomic_dec(&skc->skc_ref); - return (obj); } EXPORT_SYMBOL(spl_kmem_cache_alloc); @@ -1479,7 +1475,6 @@ spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj) ASSERT(skc->skc_magic == SKC_MAGIC); ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags)); - atomic_inc(&skc->skc_ref); /* * Run the destructor @@ -1492,7 +1487,7 @@ spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj) */ if (skc->skc_flags & KMC_SLAB) { kmem_cache_free(skc->skc_linux_cache, obj); - goto out; + return; } /* @@ -1507,7 +1502,7 @@ spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj) spin_unlock(&skc->skc_lock); if (do_emergency && (spl_emergency_free(skc, obj) == 0)) - goto out; + return; } local_irq_save(flags); @@ -1538,8 +1533,6 @@ spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj) if (do_reclaim) spl_slab_reclaim(skc); -out: - atomic_dec(&skc->skc_ref); } EXPORT_SYMBOL(spl_kmem_cache_free); -- cgit v1.2.3