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authorChristoph Lameter <cl@linux.com>2010-12-08 16:22:55 +0100
committerTejun Heo <tj@kernel.org>2010-12-17 15:07:19 +0100
commit909ea96468096b07fbb41aaf69be060d92bd9271 (patch)
treea7e015edd96b5f674874fe78cdd889769e130a2a /mm/slab.c
parent780f36d8b3fa9572f731d4fb85067b2e45e6f993 (diff)
downloadlinux-909ea96468096b07fbb41aaf69be060d92bd9271.tar.gz
core: Replace __get_cpu_var with __this_cpu_read if not used for an address.
__get_cpu_var() can be replaced with this_cpu_read and will then use a
single read instruction with implied address calculation to access the
correct per cpu instance.

However, the address of a per cpu variable passed to __this_cpu_read()
cannot be determined (since it's an implied address conversion through
segment prefixes).  Therefore apply this only to uses of __get_cpu_var
where the address of the variable is not used.

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Hugh Dickins <hughd@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'mm/slab.c')
-rw-r--r--mm/slab.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/slab.c b/mm/slab.c
index b1e40dafbab3..316d75596f3c 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -829,12 +829,12 @@ static void init_reap_node(int cpu)
 
 static void next_reap_node(void)
 {
-	int node = __get_cpu_var(slab_reap_node);
+	int node = __this_cpu_read(slab_reap_node);
 
 	node = next_node(node, node_online_map);
 	if (unlikely(node >= MAX_NUMNODES))
 		node = first_node(node_online_map);
-	__get_cpu_var(slab_reap_node) = node;
+	__this_cpu_write(slab_reap_node, node);
 }
 
 #else
@@ -1012,7 +1012,7 @@ static void __drain_alien_cache(struct kmem_cache *cachep,
  */
 static void reap_alien(struct kmem_cache *cachep, struct kmem_list3 *l3)
 {
-	int node = __get_cpu_var(slab_reap_node);
+	int node = __this_cpu_read(slab_reap_node);
 
 	if (l3->alien) {
 		struct array_cache *ac = l3->alien[node];