slub: Add statistics for the case that the current slab does not match the node

Slub reloads the per cpu slab if the page does not satisfy the NUMA condition. Track
those reloads since doing so has a performance impact.

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

2 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index b42715294147..5b228b785377 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -24,6 +24,7 @@ enum stat_item {
         ALLOC_FROM_PARTIAL,     /* Cpu slab acquired from partial list */
         ALLOC_SLAB,             /* Cpu slab acquired from page allocator */
         ALLOC_REFILL,           /* Refill cpu slab from slab freelist */
+        ALLOC_NODE_MISMATCH,    /* Switching cpu slab */
         FREE_SLAB,              /* Slab freed to the page allocator */
         CPUSLAB_FLUSH,          /* Abandoning of the cpu slab */
         DEACTIVATE_FULL,        /* Cpu slab was full when deactivated */
diff --git a/mm/slub.c b/mm/slub.c
index 41a15c1d8068..e00b7732f556 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1966,6 +1966,7 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
                 goto new_slab;
 
         if (unlikely(!node_match(c, node))) {
+                stat(s, ALLOC_NODE_MISMATCH);
                 deactivate_slab(s, c);
                 goto new_slab;
         }
@@ -4671,6 +4672,7 @@ STAT_ATTR(FREE_REMOVE_PARTIAL, free_remove_partial);
 STAT_ATTR(ALLOC_FROM_PARTIAL, alloc_from_partial);
 STAT_ATTR(ALLOC_SLAB, alloc_slab);
 STAT_ATTR(ALLOC_REFILL, alloc_refill);
+STAT_ATTR(ALLOC_NODE_MISMATCH, alloc_node_mismatch);
 STAT_ATTR(FREE_SLAB, free_slab);
 STAT_ATTR(CPUSLAB_FLUSH, cpuslab_flush);
 STAT_ATTR(DEACTIVATE_FULL, deactivate_full);
@@ -4730,6 +4732,7 @@ static struct attribute *slab_attrs[] = {
         &alloc_from_partial_attr.attr,
         &alloc_slab_attr.attr,
         &alloc_refill_attr.attr,
+        &alloc_node_mismatch_attr.attr,
         &free_slab_attr.attr,
         &cpuslab_flush_attr.attr,
         &deactivate_full_attr.attr,