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Subject[120/200] slub: move kmem_cache_node into its own cacheline
2.6.34-stable review patch.  If anyone has any objections, please let me know.

------------------
From: Alexander Duyck <alexander.h.duyck@intel.com>

commit 73367bd8eef4f4eb311005886aaa916013073265 upstream.

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
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
include/linux/slub_def.h | 9 +++------
mm/slub.c | 33 +++++++++++----------------------
2 files changed, 14 insertions(+), 28 deletions(-)
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -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
};

--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2141,7 +2141,7 @@ static void free_kmem_cache_nodes(struct

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;
}
@@ -2150,33 +2150,22 @@ static void free_kmem_cache_nodes(struct
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);
}



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