linux-kernel - Re: [v8 0/4] cgroup-aware OOM killer

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Message-ID: <20170927074319.o3k26kja43rfqmvb@dhcp22.suse.cz>
Date:   Wed, 27 Sep 2017 09:43:19 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Tim Hockin <thockin@...kin.org>
Cc:     Johannes Weiner <hannes@...xchg.org>, Roman Gushchin <guro@...com>,
        Tejun Heo <tj@...nel.org>, kernel-team@...com,
        David Rientjes <rientjes@...gle.com>, linux-mm@...ck.org,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Cgroups <cgroups@...r.kernel.org>, linux-doc@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [v8 0/4] cgroup-aware OOM killer

On Tue 26-09-17 20:37:37, Tim Hockin wrote:
[...]
> I feel like David has offered examples here, and many of us at Google
> have offered examples as long ago as 2013 (if I recall) of cases where
> the proposed heuristic is EXACTLY WRONG.

I do not think we have discussed anything resembling the current
approach. And I would really appreciate some more examples where
decisions based on leaf nodes would be EXACTLY WRONG.

> We need OOM behavior to kill in a deterministic order configured by
> policy.

And nobody is objecting to this usecase. I think we can build a priority
policy on top of leaf-based decision as well. The main point we are
trying to sort out here is a reasonable semantic that would work for
most workloads. Sibling based selection will simply not work on those
that have to use deeper hierarchies for organizational purposes. I
haven't heard a counter argument for that example yet.
-- 
Michal Hocko
SUSE Labs