linux-kernel - Re: [PATCH v3] mm/oom_kill: show oom eligibility when displaying the current memory state of all tasks

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Message-ID: <20210803103222.wethf6pj3rh2b2uq@ava.usersys.com>
Date:   Tue, 3 Aug 2021 11:32:22 +0100
From:   Aaron Tomlin <atomlin@...hat.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     linux-mm@...ck.org, akpm@...ux-foundation.org,
        penguin-kernel@...ove.sakura.ne.jp, rientjes@...gle.com,
        llong@...hat.com, neelx@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] mm/oom_kill: show oom eligibility when displaying the
 current memory state of all tasks

On Tue 2021-08-03 09:05 +0200, Michal Hocko wrote:
> There were some attempts to print oom_score during OOM. E.g.
> http://lkml.kernel.org/r/20190808183247.28206-1-echron@arista.com. That
> one was rejected on the grounds that the number on its own doesn't
> really present any real value. It is really only valuable when comparing
> to other potential oom victims. I have to say I am still worried about
> printing this internal scoring as it should have really been an
> implementation detail but with /proc/<pid>/oom_score this is likely a
> lost battle and I am willing to give up on that front.

Understood.

> I am still not entirely convinced this is worth doing though.
> oom_badness is not a cheap operation. task_lock has to be taken again
> during dump_tasks for each task so the already quite expensive operation
> will be more so. Is this really something we cannot live without?

Fair enough and I now agree, it is unquestionably not worth it.



Kind regards,

-- 
Aaron Tomlin