linux-kernel - Re: [RFC][PATCH] memcg soft limit (yet another new design) v1

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Date:	Tue, 31 Mar 2009 15:28:43 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	balbir@...ux.vnet.ibm.com
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"kosaki.motohiro@...fujitsu.com" <kosaki.motohiro@...fujitsu.com>,
	"nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>
Subject: Re: [RFC][PATCH] memcg soft limit (yet another new design) v1

On Tue, 31 Mar 2009 11:40:10 +0530
Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:

> > > Swapout for A? For A it is expected, but for B it is not. How many
> > > nodes do you have on your machine? Any fake numa nodes?
> > > 
> > Of course, from B.
> >
> 
> I asked because I see A have a swapout of 350 MB, which is expected
> since it is way over its soft limit.
>  
gcc doesn't use so much RSS..ld ?

> > Nothing special boot options. My test was on VMware 2cpus/1.6GB memory.
> > 
> > I wonder why swapout can be 0 on your test. Do you add some extra hooks to
> > kswapd ?
> >
> 
> Nope.. no special hooks to kswapd. B never enters the RB-Tree and thus
> never hits the memcg soft limit reclaim path. kswapd can reclaim from
> it, but it grows back quickly.
Why grows back ? tasks in B sleeps ?

>  At some point, memcg soft limit reclaim
> hits A and reclaims memory from it, allowing B to run without any
> problems. I am talking about the state at the end of the experiment.
> 
Considering LRU rotation (ACTIVE->INACTIVE), pages in group B never goes back
to ACTIVE list and can be the first candidates for swap-out via kswapd.

Hmm....kswapd doesn't work at all ?

(or 1700MB was too much.)

Thanks,
-Kame


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