[RFC/PATCH 5/6] memcg: optimize branch

摘自: LKML  被阅读次数: 31


由'机器人'于 2008-05-14 16:01:56 提供


DateWed, 14 May 2008 17:11:10 +0900
FromKAMEZAWA Hiroyuki <>
Subject[RFC/PATCH 5/6] memcg: optimize branch
Showing brach direction for obvious conditions.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
 mm/memcontrol.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
Index: linux-2.6.26-rc2/mm/memcontrol.c
===================================================================
--- linux-2.6.26-rc2.orig/mm/memcontrol.c
+++ linux-2.6.26-rc2/mm/memcontrol.c
@@ -550,7 +550,7 @@ retry:
 	 * The page_cgroup exists and
 	 * the page has already been accounted.
 	 */
-	if (pc) {
+	if (unlikely(pc)) {
 		VM_BUG_ON(pc->page != page);
 		VM_BUG_ON(!pc->mem_cgroup);
 		unlock_page_cgroup(page);
@@ -559,7 +559,7 @@ retry:
 	unlock_page_cgroup(page);
 
 	pc = kmem_cache_alloc(page_cgroup_cache, gfp_mask);
-	if (pc == NULL)
+	if (unlikely(pc == NULL))
 		goto err;
 
 	/*
@@ -616,7 +616,7 @@ retry:
 		pc->flags = PAGE_CGROUP_FLAG_ACTIVE;
 
 	lock_page_cgroup(page);
-	if (page_get_page_cgroup(page)) {
+	if (unlikely(page_get_page_cgroup(page))) {
 		unlock_page_cgroup(page);
 		/*
 		 * Another charge has been added to this page already.
@@ -689,7 +689,7 @@ void __mem_cgroup_uncharge_common(struct
 	 */
 	lock_page_cgroup(page);
 	pc = page_get_page_cgroup(page);
-	if (!pc)
+	if (unlikely(!pc))
 		goto unlock;
 
 	VM_BUG_ON(pc->page != page);
--
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原文链接: http://lkml.org/lkml/2008/5/14/79
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