From: Corey Minyard <cminyard@mvista.com>
To: Michal Hocko <mhocko@suse.com>
Cc: minyard@acm.org, Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] oom_kill: oom_score_adj broken for processes with small memory usage
Date: Fri, 16 Jul 2021 07:25:47 -0500 [thread overview]
Message-ID: <20210716122547.GI3431@minyard.net> (raw)
In-Reply-To: <YPEW3H+W/uiRYIfn@dhcp22.suse.cz>
On Fri, Jul 16, 2021 at 07:19:24AM +0200, Michal Hocko wrote:
> On Thu 01-07-21 07:54:30, minyard@acm.org wrote:
> > From: Corey Minyard <cminyard@mvista.com>
> >
> > If you have a process with less than 1000 totalpages, the calculation:
> >
> > adj = (long)p->signal->oom_score_adj;
> > ...
> > adj *= totalpages / 1000;
> >
> > will always result in adj being zero no matter what oom_score_adj is,
> > which could result in the wrong process being picked for killing.
> >
> > Fix by adding 1000 to totalpages before dividing.
>
> Yes, this is a known limitation of the oom_score_adj and its scale.
> Is this a practical problem to be solved though? I mean 0-1000 pages is
> not really that much different from imprecision at a larger scale where
> tasks are effectively considered equal.
Known limitation? Is this documented? I couldn't find anything that
said "oom_score_adj doesn't work at all with programs with <1000 pages
besides setting the value to -1000".
>
> I have to say I do not really like the proposed workaround. It doesn't
> really solve the problem yet it adds another special case.
The problem is that if you have a small program, there is no way to
set it's priority besides completely disablling the OOM killer for
it.
I don't understand the special case comment. How is this adding a
special case? This patch removes a special case. Small programs
working different than big programs is a special case. Making them all
work the same is removing an element of surprise from someone expecting
things to work as documented.
-corey
next prev parent reply other threads:[~2021-07-16 12:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-01 12:54 [PATCH] oom_kill: oom_score_adj broken for processes with small memory usage minyard
2021-07-16 5:19 ` Michal Hocko
2021-07-16 12:25 ` Corey Minyard [this message]
2021-09-02 19:55 ` Andrew Morton
2021-09-03 1:52 ` Corey Minyard
2021-09-03 7:49 ` Michal Hocko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210716122547.GI3431@minyard.net \
--to=cminyard@mvista.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
--cc=minyard@acm.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).