linux-kernel - Re: Help Resource Counters Scale Better (v3)

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Date:	Mon, 10 Aug 2009 10:52:43 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, andi.kleen@...el.com,
	Prarit Bhargava <prarit@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	"lizf@...fujitsu.com" <lizf@...fujitsu.com>,
	"menage@...gle.com" <menage@...gle.com>,
	Pavel Emelianov <xemul@...nvz.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: Help Resource Counters Scale Better (v3)

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> [2009-08-10 09:43:44]:

> On Mon, 10 Aug 2009 09:32:29 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote:
> 
> > 1. you use res_counter_read_positive() in force_empty. It seems force_empty can
> >    go into infinite loop. plz check. (especially when some pages are freed or swapped-in
> >    in other cpu while force_empry runs.)
> > 
> > 2. In near future, we'll see 256 or 1024 cpus on a system, anyway.
> >    Assume 1024cpu system, 64k*1024=64M is a tolerance.
> >    Can't we calculate max-tolerane as following ?
> >   
> >    tolerance = min(64k * num_online_cpus(), limit_in_bytes/100);
> >    tolerance /= num_online_cpus();
> >    per_cpu_tolerance = min(16k, tolelance);
> > 
> >    I think automatic runtine adjusting of tolerance will be finally necessary,
> >    but above will not be very bad because we can guarantee 1% tolerance.
> > 
> 
> Sorry, one more.
> 
> 3. As I requested when you pushed softlimit changes to mmotom, plz consider
>    to implement a way to check-and-notify gadget to res_counter.
>    See: http://marc.info/?l=linux-mm&m=124753058921677&w=2
>

Yes, I will do that, but only after the scaling, since this is more
important at the moment. 

-- 
	Balbir
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