linux-kernel - Re: [PATCH 0/4] Memory controller soft limit patches (v4)

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Message-ID: <20090306100534.GD5482@balbir.in.ibm.com>
Date:	Fri, 6 Mar 2009 15:35:34 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	linux-mm@...ck.org, Sudhir Kumar <skumar@...ux.vnet.ibm.com>,
	YAMAMOTO Takashi <yamamoto@...inux.co.jp>,
	Bharata B Rao <bharata@...ibm.com>,
	Paul Menage <menage@...gle.com>, lizf@...fujitsu.com,
	linux-kernel@...r.kernel.org,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	David Rientjes <rientjes@...gle.com>,
	Pavel Emelianov <xemul@...nvz.org>,
	Dhaval Giani <dhaval@...ux.vnet.ibm.com>,
	Rik van Riel <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 0/4] Memory controller soft limit patches (v4)

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> [2009-03-06 18:54:40]:

> On Fri, 06 Mar 2009 14:53:23 +0530
> Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
> 
> > 
> > From: Balbir Singh <balbir@...ux.vnet.ibm.com>
> > 
> > New Feature: Soft limits for memory resource controller.
> > 
> > Changelog v4...v3
> > 1. Adopted suggestions from Kamezawa to do a per-zone-per-node reclaim
> >    while doing soft limit reclaim. We don't record priorities while
> >    doing soft reclaim
> > 2. Some of the overheads associated with soft limits (like calculating
> >    excess each time) is eliminated
> > 3. The time_after(jiffies, 0) bug has been fixed
> > 4. Tasks are throttled if the mem cgroup they belong to is being soft reclaimed
> >    and at the same time tasks are increasing the memory footprint and causing
> >    the mem cgroup to exceed its soft limit.
> > 
> I don't think this "4" is necessary.
>

I responded to it and I had asked for review for this. Lets discuss it
there. I am open to doing this or not.
 
> 
> > Changelog v3...v2
> > 1. Implemented several review comments from Kosaki-San and Kamezawa-San
> >    Please see individual changelogs for changes
> > 
> > Changelog v2...v1
> > 1. Soft limits now support hierarchies
> > 2. Use spinlocks instead of mutexes for synchronization of the RB tree
> > 
> > Here is v4 of the new soft limit implementation. Soft limits is a new feature
> > for the memory resource controller, something similar has existed in the
> > group scheduler in the form of shares. The CPU controllers interpretation
> > of shares is very different though. 
> > 
> > Soft limits are the most useful feature to have for environments where
> > the administrator wants to overcommit the system, such that only on memory
> > contention do the limits become active. The current soft limits implementation
> > provides a soft_limit_in_bytes interface for the memory controller and not
> > for memory+swap controller. The implementation maintains an RB-Tree of groups
> > that exceed their soft limit and starts reclaiming from the group that
> > exceeds this limit by the maximum amount.
> > 
> > If there are no major objections to the patches, I would like to get them
> > included in -mm.
> > 
> You got Nack from me, again ;) And you know why.
> I'll post my one later, I hope that one will be good input for you.
>

Lets discuss the patches and your objections. I suspect it is because
of 4 above, but I don't want to keep guessing. 

-- 
	Balbir
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