From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751453AbdIOPXd (ORCPT ); Fri, 15 Sep 2017 11:23:33 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:57656 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751190AbdIOPXa (ORCPT ); Fri, 15 Sep 2017 11:23:30 -0400 Date: Fri, 15 Sep 2017 08:23:01 -0700 From: Roman Gushchin To: Michal Hocko CC: David Rientjes , , Vladimir Davydov , Johannes Weiner , Tetsuo Handa , Andrew Morton , Tejun Heo , , , , Subject: Re: [v8 0/4] cgroup-aware OOM killer Message-ID: <20170915152301.GA29379@castle> References: <20170911131742.16482-1-guro@fb.com> <20170913122914.5gdksbmkolum7ita@dhcp22.suse.cz> <20170913215607.GA19259@castle> <20170914134014.wqemev2kgychv7m5@dhcp22.suse.cz> <20170914160548.GA30441@castle> <20170915105826.hq5afcu2ij7hevb4@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20170915105826.hq5afcu2ij7hevb4@dhcp22.suse.cz> User-Agent: Mutt/1.8.3 (2017-05-23) X-Originating-IP: [2620:10d:c090:180::1:d566] X-ClientProxiedBy: BN6PR17CA0016.namprd17.prod.outlook.com (2603:10b6:404:65::26) To DM3PR15MB1083.namprd15.prod.outlook.com (2603:10b6:0:12::9) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 9cac16d8-c53e-4fd0-e025-08d4fc4dab71 X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(300000500095)(300135000095)(300000501095)(300135300095)(22001)(300000502095)(300135100095)(2017030254152)(300000503095)(300135400095)(2017052603199)(201703131423075)(201703031133081)(201702281549075)(300000504095)(300135200095)(300000505095)(300135600095)(300000506095)(300135500095);SRVR:DM3PR15MB1083; 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I believe the same principle > > > > should be used for cgroups. > > > > > > Yes bigger cgroups should be preferred but I fail to see why bigger > > > hierarchies should be considered as well if they are not kill-all. And > > > whether non-leaf memcgs should allow kill-all is not entirely clear to > > > me. What would be the usecase? > > > > We definitely want to support kill-all for non-leaf cgroups. > > A workload can consist of several cgroups and we want to clean up > > the whole thing on OOM. > > Could you be more specific about such a workload? E.g. how can be such a > hierarchy handled consistently when its sub-tree gets killed due to > internal memory pressure? Or just system-wide OOM. > Or do you expect that none of the subtree will > have hard limit configured? And this can also be a case: the whole workload may have hard limit configured, while internal memcgs have only memory.low set for "soft" prioritization. > > But then you just enforce a structural restriction on your configuration > because > root > / \ > A D > /\ > B C > > is a different thing than > root > / | \ > B C D > I actually don't have a strong argument against an approach to select largest leaf or kill-all-set memcg. I think, in practice there will be no much difference. The only real concern I have is that then we have to do the same with oom_priorities (select largest priority tree-wide), and this will limit an ability to enforce the priority by parent cgroup. Thanks!