linux-kernel - Re: Re: [PATCH v2 0/5] mm, oom: Introduce per numa node oom for CONSTRAINT_{MEMORY

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Message-ID: <Ysf629IWfT5b58oD@dhcp22.suse.cz>
Date:   Fri, 8 Jul 2022 11:37:31 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     Gang Li <ligang.bdlg@...edance.com>
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Subject: Re: Re: [PATCH v2 0/5] mm, oom: Introduce per numa node oom for
 CONSTRAINT_{MEMORY_POLICY,CPUSET}

On Fri 08-07-22 17:25:31, Gang Li wrote:
> Oh apologize. I just realized what you mean.
> 
> I should try a "cpuset cgroup oom killer" selecting victim from a
> specific cpuset cgroup.

yes, that was the idea. Many workloads which really do care about
particioning the NUMA system tend to use cpusets. In those cases you
have reasonably defined boundaries and the current OOM killer
imeplementation is not really aware of that. The oom selection process
could be enhanced/fixed to select victims from those cpusets similar to
how memcg oom killer victim selection is done.

There is no additional accounting required for this approach because the
workload is partitioned on the cgroup level already. Maybe this is not
really the best fit for all workloads but it should be reasonably simple
to implement without intrusive or runtime visible changes.

I am not saying per-numa accounting is wrong or a bad idea. I would just
like to see a stronger justification for that and also some arguments
why a simpler approach via cpusets is not viable.

Does this make sense to you?

-- 
Michal Hocko
SUSE Labs