Re: [percpu] BUG: using __this_cpu_add() in preemptible [00000000] code: init/1

[Christoph Lameter]

Anyways the statistics in slub should be low impact and able to
be placed anywhere. So I think we need this patch to avoid
the preemption checks begin triggered.


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.

__this_cpu_inc now checks if preemption is disabled and 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.

Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>

Index: linux/mm/slub.c
===================================================================
--- linux.orig/mm/slub.c	2014-03-07 14:10:30.142777022 -0600
+++ linux/mm/slub.c	2014-03-18 09:39:15.675035324 -0500
@@ -224,7 +224,7 @@
 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]);
+	raw_cpu_inc(s->cpu_slab->stat[si]);
 #endif
 }

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/