linux-kernel - Re: [PATCH 00/10] OOM Debug print selection and additional information

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Message-ID: <CAM3twVS+yAyBAzNHs7C8NLVXT6MmSamemXNMpmvmkzkFwu5b_A@mail.gmail.com>
Date:   Thu, 29 Aug 2019 09:35:19 -0700
From:   Edward Chron <echron@...sta.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Roman Gushchin <guro@...com>,
        Johannes Weiner <hannes@...xchg.org>,
        David Rientjes <rientjes@...gle.com>,
        Shakeel Butt <shakeelb@...gle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Ivan Delalande <colona@...sta.com>
Subject: Re: [PATCH 00/10] OOM Debug print selection and additional information

On Thu, Aug 29, 2019 at 9:18 AM Michal Hocko <mhocko@...nel.org> wrote:
>
> On Thu 29-08-19 08:03:19, Edward Chron wrote:
> > On Thu, Aug 29, 2019 at 4:56 AM Michal Hocko <mhocko@...nel.org> wrote:
> [...]
> > > Or simply provide a hook with the oom_control to be called to report
> > > without replacing the whole oom killer behavior. That is not necessary.
> >
> > For very simple addition, to add a line of output this works.
>
> Why would a hook be limited to small stuff?

It could be larger but the few items we added were just a line or
two of output.

The vmalloc, slabs and processes can print many entries so we
added a control for those.

>
> > It would still be nice to address the fact the existing OOM Report prints
> > all of the user processes or none. It would be nice to add some control
> > for that. That's what we did.
>
> TBH, I am not really convinced partial taks list is desirable nor easy
> to configure. What is the criterion? oom_score (with potentially unstable
> metric)? Rss? Something else?

We used an estimate of the memory footprint of the process:
rss, swap pages and page table pages.

> --
> Michal Hocko
> SUSE Labs