linux-kernel - Re: [RFC][PATCH][0/4] Memory controller (RSS Control)

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Message-ID: <45D97FAD.9070009@in.ibm.com>
Date:	Mon, 19 Feb 2007 16:15:01 +0530
From:	Balbir Singh <balbir@...ibm.com>
To:	Magnus Damm <magnus.damm@...il.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, vatsa@...ibm.com,
	ckrm-tech@...ts.sourceforge.net, xemul@...ru, linux-mm@...ck.org,
	menage@...gle.com, svaidy@...ux.vnet.ibm.com, devel@...nvz.org
Subject: Re: [RFC][PATCH][0/4] Memory controller (RSS Control)

Magnus Damm wrote:
> On 2/19/07, Andrew Morton <akpm@...ux-foundation.org> wrote:
>> On Mon, 19 Feb 2007 12:20:19 +0530 Balbir Singh <balbir@...ibm.com> 
>> wrote:
>>
>> > This patch applies on top of Paul Menage's container patches (V7) 
>> posted at
>> >
>> >       http://lkml.org/lkml/2007/2/12/88
>> >
>> > It implements a controller within the containers framework for limiting
>> > memory usage (RSS usage).
> 
>> The key part of this patchset is the reclaim algorithm:
>>
>> Alas, I fear this might have quite bad worst-case behaviour.  One small
>> container which is under constant memory pressure will churn the
>> system-wide LRUs like mad, and will consume rather a lot of system time.
>> So it's a point at which container A can deleteriously affect things 
>> which
>> are running in other containers, which is exactly what we're supposed to
>> not do.
> 
> Nice with a simple memory controller. The downside seems to be that it
> doesn't scale very well when it comes to reclaim, but maybe that just
> comes with being simple. Step by step, and maybe this is a good first
> step?
> 

Thanks, I totally agree.

> Ideally I'd like to see unmapped pages handled on a per-container LRU
> with a fallback to the system-wide LRUs. Shared/mapped pages could be
> handled using PTE ageing/unmapping instead of page ageing, but that
> may consume too much resources to be practical.
> 
> / magnus

Keeping unmapped pages per container sounds interesting. I am not quite
sure what PTE ageing, will it look it up.


-- 
	Warm Regards,
	Balbir Singh
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