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authorMichal Hocko <mhocko@suse.cz>2013-09-12 15:13:25 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-12 15:38:00 -0700
commita5b7c87f92076352dbff2fe0423ec255e1c9a71b (patch)
treefbc14b98d1412a078fc570914b050cd618e359f2 /mm
parente883110aad718b65de658db77387aaa69cce996d (diff)
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vmscan, memcg: do softlimit reclaim also for targeted reclaim
Soft reclaim has been done only for the global reclaim (both background and direct). Since "memcg: integrate soft reclaim tighter with zone shrinking code" there is no reason for this limitation anymore as the soft limit reclaim doesn't use any special code paths and it is a part of the zone shrinking code which is used by both global and targeted reclaims. From the semantic point of view it is natural to consider soft limit before touching all groups in the hierarchy tree which is touching the hard limit because soft limit tells us where to push back when there is a memory pressure. It is not important whether the pressure comes from the limit or imbalanced zones. This patch simply enables soft reclaim unconditionally in mem_cgroup_should_soft_reclaim so it is enabled for both global and targeted reclaim paths. mem_cgroup_soft_reclaim_eligible needs to learn about the root of the reclaim to know where to stop checking soft limit state of parents up the hierarchy. Say we have A (over soft limit) \ B (below s.l., hit the hard limit) / \ C D (below s.l.) B is the source of the outside memory pressure now for D but we shouldn't soft reclaim it because it is behaving well under B subtree and we can still reclaim from C (pressumably it is over the limit). mem_cgroup_soft_reclaim_eligible should therefore stop climbing up the hierarchy at B (root of the memory pressure). Signed-off-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Glauber Costa <glommer@openvz.org> Reviewed-by: Tejun Heo <tj@kernel.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c14
-rw-r--r--mm/vmscan.c4
2 files changed, 11 insertions, 7 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 87a448dd9c10..c016e001c5b2 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1773,11 +1773,13 @@ int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
#endif
/*
- * A group is eligible for the soft limit reclaim if it is
- * a) is over its soft limit
+ * A group is eligible for the soft limit reclaim under the given root
+ * hierarchy if
+ * a) it is over its soft limit
* b) any parent up the hierarchy is over its soft limit
*/
-bool mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg)
+bool mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg,
+ struct mem_cgroup *root)
{
struct mem_cgroup *parent = memcg;
@@ -1785,12 +1787,14 @@ bool mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg)
return true;
/*
- * If any parent up the hierarchy is over its soft limit then we
- * have to obey and reclaim from this group as well.
+ * If any parent up to the root in the hierarchy is over its soft limit
+ * then we have to obey and reclaim from this group as well.
*/
while((parent = parent_mem_cgroup(parent))) {
if (res_counter_soft_limit_excess(&parent->res))
return true;
+ if (parent == root)
+ break;
}
return false;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index cf4643807ec2..1896e7ca494b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -142,7 +142,7 @@ static bool global_reclaim(struct scan_control *sc)
static bool mem_cgroup_should_soft_reclaim(struct scan_control *sc)
{
- return !mem_cgroup_disabled() && global_reclaim(sc);
+ return !mem_cgroup_disabled();
}
#else
static bool global_reclaim(struct scan_control *sc)
@@ -2161,7 +2161,7 @@ __shrink_zone(struct zone *zone, struct scan_control *sc, bool soft_reclaim)
struct lruvec *lruvec;
if (soft_reclaim &&
- !mem_cgroup_soft_reclaim_eligible(memcg)) {
+ !mem_cgroup_soft_reclaim_eligible(memcg, root)) {
memcg = mem_cgroup_iter(root, memcg, &reclaim);
continue;
}