From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 21C896B0038 for ; Tue, 12 Sep 2017 16:23:05 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id q75so22047543pfl.1 for ; Tue, 12 Sep 2017 13:23:05 -0700 (PDT) Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id a186sor3674664pge.388.2017.09.12.13.23.02 for (Google Transport Security); Tue, 12 Sep 2017 13:23:03 -0700 (PDT) Date: Tue, 12 Sep 2017 13:23:00 -0700 (PDT) From: David Rientjes Subject: Re: [v8 3/4] mm, oom: add cgroup v2 mount option for cgroup-aware OOM killer In-Reply-To: <20170912200115.GA25218@castle> Message-ID: References: <20170911131742.16482-1-guro@fb.com> <20170911131742.16482-4-guro@fb.com> <20170912200115.GA25218@castle> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Roman Gushchin Cc: linux-mm@kvack.org, Michal Hocko , Vladimir Davydov , Johannes Weiner , Tetsuo Handa , Andrew Morton , Tejun Heo , kernel-team@fb.com, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org On Tue, 12 Sep 2017, Roman Gushchin wrote: > > I can't imagine that Tejun would be happy with a new mount option, > > especially when it's not required. > > > > OOM behavior does not need to be defined at mount time and for the entire > > hierarchy. It's possible to very easily implement a tunable as part of > > mem cgroup that is propagated to descendants and controls the oom scoring > > behavior for that hierarchy. It does not need to be system wide and > > affect scoring of all processes based on which mem cgroup they are > > attached to at any given time. > > No, I don't think that mixing per-cgroup and per-process OOM selection > algorithms is a good idea. > > So, there are 3 reasonable options: > 1) boot option > 2) sysctl > 3) cgroup mount option > > I believe, 3) is better, because it allows changing the behavior dynamically, > and explicitly depends on v2 (what sysctl lacks). > > So, the only question is should it be opt-in or opt-out option. > Personally, I would prefer opt-out, but Michal has a very strong opinion here. > If it absolutely must be a mount option, then I would agree it should be opt-in so that it's known what is being changed rather than changing how selection was done in the past and requiring legacy users to now mount in a new way. I'd be interested to hear Tejun's comments, however, about whether we want to add controller specific mount options like this instead of a tunable at the root level, for instance, that controls victim selection and would be isolated to the memory cgroup controller as opposed to polluting mount options. -- 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