From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751619AbeA3MN5 (ORCPT ); Tue, 30 Jan 2018 07:13:57 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:55864 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751391AbeA3MNy (ORCPT ); Tue, 30 Jan 2018 07:13:54 -0500 Date: Tue, 30 Jan 2018 12:13:22 +0000 From: Roman Gushchin To: Michal Hocko CC: Tejun Heo , Andrew Morton , David Rientjes , Vladimir Davydov , Johannes Weiner , Tetsuo Handa , , , , , Subject: Re: [patch -mm v2 2/3] mm, memcg: replace cgroup aware oom killer mount option with tunable Message-ID: <20180130121315.GA5888@castle.DHCP.thefacebook.com> References: <20180125160016.30e019e546125bb13b5b6b4f@linux-foundation.org> <20180126143950.719912507bd993d92188877f@linux-foundation.org> <20180126161735.b999356fbe96c0acd33aaa66@linux-foundation.org> <20180129104657.GC21609@dhcp22.suse.cz> <20180129191139.GA1121507@devbig577.frc2.facebook.com> <20180130085445.GQ21609@dhcp22.suse.cz> <20180130115846.GA4720@castle.DHCP.thefacebook.com> <20180130120852.GA21609@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; 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Isn't it? > > > > > +Leaf cgroups are compared based on their cumulative memory usage. The > > > +root cgroup is treated as a leaf memory cgroup as well, so it's > > > +compared with other leaf memory cgroups. Due to internal implementation > > > +restrictions the size of the root cgroup is a cumulative sum of > > > +oom_badness of all its tasks (in other words oom_score_adj of each task > > > +is obeyed). Relying on oom_score_adj (appart from OOM_SCORE_ADJ_MIN) > > > +can lead to overestimating of the root cgroup consumption and it is > > > > Hm, and underestimating too. Also OOM_SCORE_ADJ_MIN isn't any different > > in this case. Say, all tasks except a small one have OOM_SCORE_ADJ set to > > -999, this means the root croup has extremely low chances to be elected. > > > > > +therefore discouraged. This might change in the future, though. > > > > Other than that looks very good to me. > > This? > > diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt > index 2eaed1e2243d..34ad80ee90f2 100644 > --- a/Documentation/cgroup-v2.txt > +++ b/Documentation/cgroup-v2.txt > @@ -1291,8 +1291,15 @@ This affects both system- and cgroup-wide OOMs. For a cgroup-wide OOM > the memory controller considers only cgroups belonging to the sub-tree > of the OOM'ing cgroup. > > -The root cgroup is treated as a leaf memory cgroup, so it's compared > -with other leaf memory cgroups and cgroups with oom_group option set. > +Leaf cgroups and cgroups with oom_group option set are compared based > +on their cumulative memory usage. The root cgroup is treated as a > +leaf memory cgroup as well, so it's compared with other leaf memory > +cgroups. Due to internal implementation restrictions the size of > +the root cgroup is a cumulative sum of oom_badness of all its tasks > +(in other words oom_score_adj of each task is obeyed). Relying on > +oom_score_adj (appart from OOM_SCORE_ADJ_MIN) can lead to over or > +underestimating of the root cgroup consumption and it is therefore > +discouraged. This might change in the future, though. Acked-by: Roman Gushchin Thank you!