memcg: add hints for branch

Showing brach direction for obvious conditions.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f46b861..04ded27 100644 (file)
--- a/mm/memcontrol.c
+++ b/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.
@@ -690,7 +690,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
         */
        lock_page_cgroup(page);
        pc = page_get_page_cgroup(page);
-       if (!pc)
+       if (unlikely(!pc))
                goto unlock;
 
        VM_BUG_ON(pc->page != page);