[PATCH] mm: optimize numa policy handling in slab allocator

Move the interrupt check from slab_node into ___cache_alloc and adds an
"unlikely()" to avoid pipeline stalls on some architectures.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

mm/mempolicy.c

@@ -982,9 +982,6 @@ static unsigned interleave_nodes(struct mempolicy *policy)
  */
 unsigned slab_node(struct mempolicy *policy)
 {
-	if (in_interrupt())
-		return numa_node_id();
-
 	switch (policy->policy) {
 	case MPOL_INTERLEAVE:
 		return interleave_nodes(policy);

mm/slab.c

@@ -2574,7 +2574,7 @@ static inline void *____cache_alloc(kmem_cache_t *cachep, gfp_t flags)
 	struct array_cache *ac;
 
 #ifdef CONFIG_NUMA
-	if (current->mempolicy) {
+	if (unlikely(current->mempolicy && !in_interrupt())) {
 		int nid = slab_node(current->mempolicy);
 
 		if (nid != numa_node_id())