linux-kernel - Re: Memory overcommit

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Message-ID: <alpine.DEB.2.00.0910272311001.15462@chino.kir.corp.google.com>
Date:	Tue, 27 Oct 2009 23:17:41 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
cc:	vedran.furac@...il.com, Hugh Dickins <hugh.dickins@...cali.co.uk>,
	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

On Wed, 28 Oct 2009, KAMEZAWA Hiroyuki wrote:

> All kernel engineers know "than expected or not" can be never known to the kernel.
> So, oom_adj workaround is used now. (by some special users.)
> OOM Killer itself is also a workaround, too.
> "No kill" is the best thing but we know there are tend to be memory-leaker on bad
> systems and all systems in this world are not perfect.
> 

Right, and historically that has been addressed by considering total_vm 
and adjusting it with oom_adj so that we can identify memory leaking tasks 
through user-defined criteria.

> Yes, some more trustable values other than vmsize/rss/time are appriciated.
> I wonder recent memory consumption speed can be an another key value.
> 

Sounds very logical.

> Anyway, current bahavior of "killing X" is a bad thing.
> We need some fixes.
> 

You can easily protect X with OOM_DISABLE, as you know.  I don't think we 
need any X-specific heuristics added to the kernel, it looks like the 
special cases have already polluted badness() enough.
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