On Tue, 22 Mar 2011, Christoph Lameter wrote:
> Index: linux-2.6/include/linux/slub_def.h
> ===================================================================
> --- linux-2.6.orig/include/linux/slub_def.h 2011-03-11 10:34:26.000000000 -0600
> +++ linux-2.6/include/linux/slub_def.h 2011-03-11 10:34:49.000000000 -0600
> @@ -32,6 +32,7 @@ enum stat_item {
> DEACTIVATE_TO_TAIL, /* Cpu slab was moved to the tail of partials */
> DEACTIVATE_REMOTE_FREES,/* Slab contained remotely freed objects */
> ORDER_FALLBACK, /* Number of times fallback was necessary */
> + CMPXCHG_DOUBLE_CPU_FAIL,/* Failure of this_cpu_cmpxchg_double */
> NR_SLUB_STAT_ITEMS };
>
> struct kmem_cache_cpu {
> Index: linux-2.6/mm/slub.c
> ===================================================================
> --- linux-2.6.orig/mm/slub.c 2011-03-11 10:34:27.000000000 -0600
> +++ linux-2.6/mm/slub.c 2011-03-11 10:34:49.000000000 -0600
> @@ -217,7 +217,7 @@ static inline void sysfs_slab_remove(str
>
> #endif
>
> -static inline void stat(struct kmem_cache *s, enum stat_item si)
> +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]);
> @@ -1551,6 +1551,7 @@ static inline void note_cmpxchg_failure(
> printk("for unknown reason: actual=%lx was=%lx target=%lx\n",
> actual_tid, tid, next_tid(tid));
> #endif
> + stat(s, CMPXCHG_DOUBLE_CPU_FAIL);
> }
>
> #endif
I see this has been merged as 4fdccdfbb465, but it seems pretty pointless
unless you export the data to userspace with the necessary STAT_ATTR() and
addition in slab_attrs.
slub: export CMPXCHG_DOUBLE_CPU_FAIL to userspace
4fdccdfbb465 ("slub: Add statistics for this_cmpxchg_double failures")
added CMPXCHG_DOUBLE_CPU_FAIL to show how many times
this_cpu_cmpxchg_double has failed, but it also needs to be exported to
userspace for consumption.
This will always be 0 if CONFIG_CMPXCHG_LOCAL is disabled.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
mm/slub.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4525,6 +4525,7 @@ STAT_ATTR(DEACTIVATE_TO_HEAD, deactivate_to_head);
STAT_ATTR(DEACTIVATE_TO_TAIL, deactivate_to_tail);
STAT_ATTR(DEACTIVATE_REMOTE_FREES, deactivate_remote_frees);
STAT_ATTR(ORDER_FALLBACK, order_fallback);
+STAT_ATTR(CMPXCHG_DOUBLE_CPU_FAIL, cmpxchg_double_cpu_fail);
#endif
static struct attribute *slab_attrs[] = {
@@ -4582,6 +4583,7 @@ static struct attribute *slab_attrs[] = {
&deactivate_to_tail_attr.attr,
&deactivate_remote_frees_attr.attr,
&order_fallback_attr.attr,
+ &cmpxchg_double_cpu_fail_attr.attr,
#endif
#ifdef CONFIG_FAILSLAB
&failslab_attr.attr,
--
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