From fbc29a25e484be073e7d762c9f7f1d4bf8aecc48 Mon Sep 17 00:00:00 2001
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Date: Wed, 15 Jun 2011 15:08:46 -0700
Subject: [PATCH] memcg: avoid percpu cached charge draining at softlimit
Based on Michal Hocko's comment.
We are not draining per cpu cached charges during soft limit reclaim
because background reclaim doesn't care about charges. It tries to free
some memory and charges will not give any.
Cached charges might influence only selection of the biggest soft limit
offender but as the call is done only after the selection has been already
done it makes no change.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/memcontrol.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c39a177bb641..cf7d027a8844 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1670,7 +1670,13 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
victim = mem_cgroup_select_victim(root_mem);
if (victim == root_mem) {
loop++;
- if (loop >= 1)
+ /*
+ * We are not draining per cpu cached charges during
+ * soft limit reclaim because global reclaim doesn't
+ * care about charges. It tries to free some memory and
+ * charges will not give any.
+ */
+ if (!check_soft && loop >= 1)
drain_all_stock_async(root_mem);
if (loop >= 2) {
/*
--
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