From 4ef461e8f4dd13a2e64c6c8f00c420d62294e2d4 Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Wed, 10 Dec 2014 15:44:16 -0800 Subject: [PATCH] memcg: remove mem_cgroup_reclaimable check from soft reclaim mem_cgroup_reclaimable() checks whether a cgroup has reclaimable pages on *any* NUMA node. However, the only place where it's called is mem_cgroup_soft_reclaim(), which tries to reclaim memory from a *specific* zone. So the way it is used is incorrect - it will return true even if the cgroup doesn't have pages on the zone we're scanning. I think we can get rid of this check completely, because mem_cgroup_shrink_node_zone(), which is called by mem_cgroup_soft_reclaim() if mem_cgroup_reclaimable() returns true, is equivalent to shrink_lruvec(), which exits almost immediately if the lruvec passed to it is empty. So there's no need to optimize anything here. Besides, we don't have such a check in the general scan path (shrink_zone) either. Signed-off-by: Vladimir Davydov Acked-by: Michal Hocko Acked-by: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 43 ------------------------------------------- 1 file changed, 43 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 3734fd6d1132..32e3b191857d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1743,52 +1743,11 @@ int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) memcg->last_scanned_node = node; return node; } - -/* - * Check all nodes whether it contains reclaimable pages or not. - * For quick scan, we make use of scan_nodes. This will allow us to skip - * unused nodes. But scan_nodes is lazily updated and may not cotain - * enough new information. We need to do double check. - */ -static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap) -{ - int nid; - - /* - * quick check...making use of scan_node. - * We can skip unused nodes. - */ - if (!nodes_empty(memcg->scan_nodes)) { - for (nid = first_node(memcg->scan_nodes); - nid < MAX_NUMNODES; - nid = next_node(nid, memcg->scan_nodes)) { - - if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap)) - return true; - } - } - /* - * Check rest of nodes. - */ - for_each_node_state(nid, N_MEMORY) { - if (node_isset(nid, memcg->scan_nodes)) - continue; - if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap)) - return true; - } - return false; -} - #else int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) { return 0; } - -static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap) -{ - return test_mem_cgroup_node_reclaimable(memcg, 0, noswap); -} #endif static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg, @@ -1832,8 +1791,6 @@ static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg, } continue; } - if (!mem_cgroup_reclaimable(victim, false)) - continue; total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false, zone, &nr_scanned); *total_scanned += nr_scanned;