linux-kernel - Re: Memory overcommit

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Message-ID: <4AE78B8F.9050201@gmail.com>
Date:	Wed, 28 Oct 2009 01:08:47 +0100
From:	Vedran Furač <vedran.furac@...il.com>
To:	David Rientjes <rientjes@...gle.com>
CC:	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	minchan.kim@...il.com, Andrew Morton <akpm@...ux-foundation.org>,
	Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: Memory overcommit

David Rientjes wrote:

> There's advantages to either approach, but it depends on the contextual 
> goal of the oom killer when it's called: kill a rogue task that is 
> allocating more memory than expected,

But it is wrong at counting allocated memory!
Come on, it kills /usr/lib/icedove/run-mozilla.sh. Parent, a shell
script, instead of its child(s) which allocated memory. Look, "test"
allocates some (0.1GB) memory, and you have:

% cat test.sh

#!/bin/sh
./test&
./test&
./test&
./test

% perl check_badness.pl|sort -n|g test

26511   7884    test
26511   7885    test
26511   7886    test
26511   7887    test
53994   7883    test.sh

// great, so test.sh "is" the bad ass, ok, emulate OOMK:

% kill -9 7883

// did we kill "a rogue task"

% perl check_badness.pl|sort -n|g test

26511   7884    test
26511   7885    test
26511   7886    test
26511   7887    test

// nooo, they are still alive and eating our memory!

QED by newbie. ;)

> or kill a task that will free the most memory.

.

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