linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Dan Kegel <dank@kegel.com>
To: Rob Landley <landley@trommello.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, linux-kernel@vger.kernel.org
Subject: OOM killer hints (was: Re: Kernel call chain search tool?)
Date: Thu, 26 Sep 2002 17:39:36 -0700	[thread overview]
Message-ID: <3D93A8C8.EB1BB878@kegel.com> (raw)
In-Reply-To: <20020927000451.98A9E398@merlin.webofficenow.com>

Rob Landley wrote:
> 
> On Thursday 26 September 2002 12:17 pm, Dan Kegel wrote:
> 
> > If only the darn program didn't have so many threads, RLIMIT_AS
> > or the no-overcommit patch would be perfect.  I unfortunately can't
> > get rid of the threads, so I'm stuck trying to figure out some way
> > to kill the right program when the system gets low on memory.
> >
> > Maybe I should look at giving the OOM killer hints?
> 
> The OOM killer should certainly know about threads and thread groups.  If you
> kill one thread, you generally have to kill the whole group because there's
> no way of knowing if that thread was holding a futex or otherwise custodian
> of critical data and thus you just threw the program into la-la land.

The OOM killer gets that part right; it kills all threads that share the
same mm.   Where it screws up is in picking the process to kill.
This is understandable, since it's a tough problem.

Hey, how about this: I could teach the OOM killer to look at
RLIMIT_RSS.  Processes which were at or nearly at their RLIMIT_RSS
would be killed first.  That would be more generally useful than
my hacky little patch, and it would be even tinier.  Like this, say:

--- oom_kill.c.orig	Thu Sep 26 17:31:12 2002
+++ oom_kill.c	Thu Sep 26 17:36:44 2002
@@ -86,6 +86,15 @@
		points *= 2;

	/*
+	 * Processes at or near their RSS or AS limits are probably causing
+	 * trouble, so double their badness points.
+	 */
+	if (((3 * p->mm->rss) / 4) >= (p->rlim[RLIMIT_RSS].rlim_max >>
PAGE_SHIFT))
+		points *= 2;
+	if (((3 * p->mm->total_vm) / 4) >= (p->rlim[RLIMIT_AS].rlim_max >>
PAGE_SHIFT))
+		points *= 2;
+
+	/*
	 * Superuser processes are usually more important, so we make it
	 * less likely that we kill those.
	 */

How's that look?
- Dan

      reply	other threads:[~2002-09-27  0:24 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-09-25  4:36 Kernel call chain search tool? Dan Kegel
2002-09-26 15:15 ` Alan Cox
2002-09-26 16:17   ` Dan Kegel
2002-09-26 19:07     ` Rob Landley
2002-09-27  0:39       ` Dan Kegel [this message]

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=3D93A8C8.EB1BB878@kegel.com \
    --to=dank@kegel.com \
    --cc=alan@lxorguk.ukuu.org.uk \
    --cc=landley@trommello.org \
    --cc=linux-kernel@vger.kernel.org \
    --subject='OOM killer hints (was: Re: Kernel call chain search tool?)' \
    /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

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).