Subject: [merged] slub-use-raw_cpu_inc-for-incrementing-statistics.patch removed from -mm tree
To: cl@xxxxxxxxx,fengguang.wu@xxxxxxxxx,penberg@xxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 08 Apr 2014 14:47:45 -0700
The patch titled
Subject: slub: use raw_cpu_inc for incrementing statistics
has been removed from the -mm tree. Its filename was
slub-use-raw_cpu_inc-for-incrementing-statistics.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Christoph Lameter <cl@xxxxxxxxx>
Subject: 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@xxxxxxxxxxxxxxxxxxxx: add comment]
Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
Cc: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff -puN mm/slub.c~slub-use-raw_cpu_inc-for-incrementing-statistics mm/slub.c
--- a/mm/slub.c~slub-use-raw_cpu_inc-for-incrementing-statistics
+++ a/mm/slub.c
@@ -224,7 +224,11 @@ static inline void memcg_propagate_slab_
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
}
_
Patches currently in -mm which might be from cl@xxxxxxxxx are
origin.patch
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