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

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Message-Id: <20090810094344.77a8ef55.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Mon, 10 Aug 2009 09:43:44 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	balbir@...ux.vnet.ibm.com,
	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)

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

Thanks,
-Kame

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