linux-kernel - Re: [PATCH 5/6] oom: don't kill random process

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Message-ID: <alpine.DEB.2.00.1106221617280.11759@chino.kir.corp.google.com>
Date:	Wed, 22 Jun 2011 16:22:17 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, caiqian@...hat.com, hughd@...gle.com,
	kamezawa.hiroyu@...fujitsu.com, minchan.kim@...il.com,
	oleg@...hat.com
Subject: Re: [PATCH 5/6] oom: don't kill random process

On Wed, 22 Jun 2011, KOSAKI Motohiro wrote:

> CAI Qian reported oom-killer killed all system daemons in his
> system at first if he ran fork bomb as root. The problem is,
> current logic give them bonus of 3% of system ram. Example,
> he has 16GB machine, then root processes have ~500MB oom
> immune. It bring us crazy bad result. _all_ processes have
> oom-score=1 and then, oom killer ignore process memroy usage
> and kill random process. This regression is caused by commit
> a63d83f427 (oom: badness heuristic rewrite).
> 

Isn't it better to give admin processes a proportional bonus instead of a 
strict 3% bonus?  I suggested 1% per 10% of memory used earlier and I 
think it would work quite well as an alternative to this.  The highest 
bonus that would actually make any differences in which thread to kill 
would be 5% when an admin process is using 50% of memory: in that case, 
another non-admin thread would have to be using >45% of memory to be 
killed instead.

Would you be satisfied with something like

	points -= (points * 10 / totalpages);

be better?
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