Messages in this thread Patch in this message | | | Date | Fri, 23 Apr 2010 22:18:38 +0300 (EEST) | From | Pekka J Enberg <> | Subject | Re: [Bug #15713] hackbench regression due to commit 9dfc6e68bfe6e |
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On Thu, 22 Apr 2010, Pekka Enberg wrote: >>> The following bug entry is on the current list of known regressions >>> from 2.6.33. Please verify if it still should be listed and let the >>> tracking team >>> know (either way). >> >> I have not been able to reproduce it so far. > > So what are our options? We can revert the SLUB conversion patch for now but > I still can't see what's wrong with it...
I haven't been able to reproduce this either on my Core 2 machine.
Yanmin, does something like this help on your machines? I'm thinking false sharing with some other per-CPU data structure that happens to be put in same percpu slot as struct kmem_cache_cpu...
Pekka
diff --git a/mm/slub.c b/mm/slub.c index 7d6c8b1..d8159d6 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2066,7 +2066,7 @@ init_kmem_cache_node(struct kmem_cache_node *n, struct kmem_cache *s) #endif }
-static DEFINE_PER_CPU(struct kmem_cache_cpu, kmalloc_percpu[KMALLOC_CACHES]); +static DEFINE_PER_CPU_ALIGNED(struct kmem_cache_cpu, kmalloc_percpu[KMALLOC_CACHES]);
static inline int alloc_kmem_cache_cpus(struct kmem_cache *s, gfp_t flags) { @@ -2077,7 +2077,7 @@ static inline int alloc_kmem_cache_cpus(struct kmem_cache *s, gfp_t flags) */ s->cpu_slab = kmalloc_percpu + (s - kmalloc_caches); else - s->cpu_slab = alloc_percpu(struct kmem_cache_cpu); + s->cpu_slab = __alloc_percpu(sizeof(struct kmem_cache_cpu), cache_line_size());
if (!s->cpu_slab) return 0;
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