From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f197.google.com (mail-qt0-f197.google.com [209.85.216.197]) by kanga.kvack.org (Postfix) with ESMTP id 9D766831F4 for ; Thu, 18 May 2017 14:37:29 -0400 (EDT) Received: by mail-qt0-f197.google.com with SMTP id v27so17331354qtg.6 for ; Thu, 18 May 2017 11:37:29 -0700 (PDT) Received: from mail-qk0-x242.google.com (mail-qk0-x242.google.com. [2607:f8b0:400d:c09::242]) by mx.google.com with ESMTPS id b1si4010682qke.97.2017.05.18.11.37.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 May 2017 11:37:28 -0700 (PDT) Received: by mail-qk0-x242.google.com with SMTP id u75so7187713qka.1 for ; Thu, 18 May 2017 11:37:28 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20170518173002.GC30148@dhcp22.suse.cz> References: <1495124884-28974-1-git-send-email-guro@fb.com> <20170518173002.GC30148@dhcp22.suse.cz> From: Balbir Singh Date: Fri, 19 May 2017 04:37:27 +1000 Message-ID: Subject: Re: [RFC PATCH] mm, oom: cgroup-aware OOM-killer Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Roman Gushchin , Johannes Weiner , Tejun Heo , Li Zefan , Vladimir Davydov , Tetsuo Handa , kernel-team@fb.com, "cgroups@vger.kernel.org" , "open list:DOCUMENTATION" , "linux-kernel@vger.kernel.org" , linux-mm On Fri, May 19, 2017 at 3:30 AM, Michal Hocko wrote: > On Thu 18-05-17 17:28:04, Roman Gushchin wrote: >> Traditionally, the OOM killer is operating on a process level. >> Under oom conditions, it finds a process with the highest oom score >> and kills it. >> >> This behavior doesn't suit well the system with many running >> containers. There are two main issues: >> >> 1) There is no fairness between containers. A small container with >> a few large processes will be chosen over a large one with huge >> number of small processes. >> >> 2) Containers often do not expect that some random process inside >> will be killed. So, in general, a much safer behavior is >> to kill the whole cgroup. Traditionally, this was implemented >> in userspace, but doing it in the kernel has some advantages, >> especially in a case of a system-wide OOM. >> >> To address these issues, cgroup-aware OOM killer is introduced. >> Under OOM conditions, it looks for a memcg with highest oom score, >> and kills all processes inside. >> >> Memcg oom score is calculated as a size of active and inactive >> anon LRU lists, unevictable LRU list and swap size. >> >> For a cgroup-wide OOM, only cgroups belonging to the subtree of >> the OOMing cgroup are considered. > > While this might make sense for some workloads/setups it is not a > generally acceptable policy IMHO. We have discussed that different OOM > policies might be interesting few years back at LSFMM but there was no > real consensus on how to do that. One possibility was to allow bpf like > mechanisms. Could you explore that path? I agree, I think it needs more thought. I wonder if the real issue is something else. For example 1. Did we overcommit a particular container too much? 2. Do we need something like https://lwn.net/Articles/604212/ to solve the problem? 3. We have oom notifiers now, could those be used (assuming you are interested in non memcg related OOM's affecting a container 4. How do we determine limits for these containers? From a fariness perspective Just trying to understand what leads to the issues you are seeing Balbir -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org