slub: move kmem_cache_node into it's own cacheline
Alexander Duyck [Fri, 21 May 2010 21:41:35 +0000 (14:41 -0700)]
This patch is meant to improve the performance of SLUB by moving the local
kmem_cache_node lock into it's own cacheline separate from kmem_cache.
This is accomplished by simply removing the local_node when NUMA is enabled.

On my system with 2 nodes I saw around a 5% performance increase w/
hackbench times dropping from 6.2 seconds to 5.9 seconds on average.  I
suspect the performance gain would increase as the number of nodes
increases, but I do not have the data to currently back that up.

Bugzilla-Reference: http://bugzilla.kernel.org/show_bug.cgi?id=15713
Cc: <stable@kernel.org>
Reported-by: Alex Shi <alex.shi@intel.com>
Tested-by: Alex Shi <alex.shi@intel.com>
Acked-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

include/linux/slub_def.h
mm/slub.c

index 55695c8..6ac3766 100644 (file)
@@ -75,12 +75,6 @@ struct kmem_cache {
        int offset;             /* Free pointer offset. */
        struct kmem_cache_order_objects oo;
 
-       /*
-        * Avoid an extra cache line for UP, SMP and for the node local to
-        * struct kmem_cache.
-        */
-       struct kmem_cache_node local_node;
-
        /* Allocation and freeing of slabs */
        struct kmem_cache_order_objects max;
        struct kmem_cache_order_objects min;
@@ -102,6 +96,9 @@ struct kmem_cache {
         */
        int remote_node_defrag_ratio;
        struct kmem_cache_node *node[MAX_NUMNODES];
+#else
+       /* Avoid an extra cache line for UP */
+       struct kmem_cache_node local_node;
 #endif
 };
 
index e46e312..c2d6e69 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2133,7 +2133,7 @@ static void free_kmem_cache_nodes(struct kmem_cache *s)
 
        for_each_node_state(node, N_NORMAL_MEMORY) {
                struct kmem_cache_node *n = s->node[node];
-               if (n && n != &s->local_node)
+               if (n)
                        kmem_cache_free(kmalloc_caches, n);
                s->node[node] = NULL;
        }
@@ -2142,33 +2142,22 @@ static void free_kmem_cache_nodes(struct kmem_cache *s)
 static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags)
 {
        int node;
-       int local_node;
-
-       if (slab_state >= UP && (s < kmalloc_caches ||
-                       s >= kmalloc_caches + KMALLOC_CACHES))
-               local_node = page_to_nid(virt_to_page(s));
-       else
-               local_node = 0;
 
        for_each_node_state(node, N_NORMAL_MEMORY) {
                struct kmem_cache_node *n;
 
-               if (local_node == node)
-                       n = &s->local_node;
-               else {
-                       if (slab_state == DOWN) {
-                               early_kmem_cache_node_alloc(gfpflags, node);
-                               continue;
-                       }
-                       n = kmem_cache_alloc_node(kmalloc_caches,
-                                                       gfpflags, node);
-
-                       if (!n) {
-                               free_kmem_cache_nodes(s);
-                               return 0;
-                       }
+               if (slab_state == DOWN) {
+                       early_kmem_cache_node_alloc(gfpflags, node);
+                       continue;
+               }
+               n = kmem_cache_alloc_node(kmalloc_caches,
+                                               gfpflags, node);
 
+               if (!n) {
+                       free_kmem_cache_nodes(s);
+                       return 0;
                }
+
                s->node[node] = n;
                init_kmem_cache_node(n, s);
        }