From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932649AbaJUNQH (ORCPT ); Tue, 21 Oct 2014 09:16:07 -0400 Received: from mx2.parallels.com ([199.115.105.18]:50593 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932170AbaJUNQE (ORCPT ); Tue, 21 Oct 2014 09:16:04 -0400 From: Vladimir Davydov To: Andrew Morton CC: Johannes Weiner , Michal Hocko , , Subject: [PATCH] memcg: remove mem_cgroup_reclaimable check from soft reclaim Date: Tue, 21 Oct 2014 17:15:50 +0400 Message-ID: <1413897350-32553-1-git-send-email-vdavydov@parallels.com> X-Mailer: git-send-email 1.7.10.4 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 how it's 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 --- mm/memcontrol.c | 43 ------------------------------------------- 1 file changed, 43 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 53393e27ff03..833b6a696aab 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1799,52 +1799,11 @@ 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, @@ -1888,8 +1847,6 @@ 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; -- 1.7.10.4