linux-kernel - Re: Improving OOM killer

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Date:	Thu, 04 Feb 2010 01:06:18 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	balbir@...ux.vnet.ibm.com
Cc:	Lubos Lunak <l.lunak@...e.cz>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Nick Piggin <npiggin@...e.de>, Jiri Kosina <jkosina@...e.cz>
Subject: Re: Improving OOM killer

On Thu, 2010-02-04 at 00:00 +0900, Minchan Kim wrote:
> On Wed, 2010-02-03 at 17:55 +0530, Balbir Singh wrote:
> > * Lubos Lunak <l.lunak@...e.cz> [2010-02-03 13:10:27]:
> >> >  I don't understand how this matters. Overcommit is memory for which address 
> > > space has been allocated but not actual memory, right? Then that's exactly 
> > > what I'm claiming is wrong and am trying to reverse. Currently OOM killer 
> > > takes this into account because it uses VmSize, but IMO it shouldn't - if a 
> > > process does malloc(400M) but then it uses only a tiny fraction of that, in 
> > > the case of memory shortage killing that process does not solve anything in 
> > > practice.
> > 
> > We have a way of tracking commmitted address space, which is more
> > sensible than just allocating memory and is used for tracking
> > overcommit. I was suggesting that, that might be a better approach.
> 
> Yes. It does make sense. At least total_vm doesn't care about
> MAP_NORESERVE case. But unfortunately, it's a per CPU not per Process.

Sorry for confusing. It was opposite. I slept :)
The commited as doesn't care about MAP_NORESERVE case. 
But it definitely charges memory. so I think total_vm is better than
committed as if we really have to use vmsize heuristic continuously.

But I am not sure that i understand your point about overcommit policy.


-- 
Kind regards,
Minchan Kim


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