slub: Add statistics for this_cmpxchg_double failures

Add some statistics for debugging.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 90fbb6d..45ca123 100644 (file)
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -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 {

diff --git a/mm/slub.c b/mm/slub.c
index e126cfb..93de30d 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -217,7 +217,7 @@ static inline void sysfs_slab_remove(struct kmem_cache *s)
 
 #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]);
@@ -1597,6 +1597,7 @@ static inline void note_cmpxchg_failure(const char *n,
                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