Commit 88da03a6 authored Apr 07, 2014 by Christoph Lameter Committed by Linus Torvalds Apr 07, 2014

slub: use raw_cpu_inc for incrementing statistics



Statistics are not critical to the operation of the allocation but
should also not cause too much overhead.

When __this_cpu_inc is altered to check if preemption is disabled this
triggers.  Use raw_cpu_inc to avoid the checks.  Using this_cpu_ops may
cause interrupt disable/enable sequences on various arches which may
significantly impact allocator performance.

[akpm@linux-foundation.org: add comment]
Signed-off-by: Christoph Lameter <cl@linux.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 3ed66e91

mm/slub.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -224,7 +224,11 @@ static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { }
		static inline void stat(const struct kmem_cache *s, enum stat_item si)
		{
		#ifdef CONFIG_SLUB_STATS
		__this_cpu_inc(s->cpu_slab->stat[si]);
		/*
		* The rmw is racy on a preemptible kernel but this is acceptable, so
		* avoid this_cpu_add()'s irq-disable overhead.
		*/
		raw_cpu_inc(s->cpu_slab->stat[si]);
		#endif
		}

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