Message-ID: <48AACF41.5090905@linux.vnet.ibm.com>
Date: Tue, 19 Aug 2008 19:18:49 +0530
From: Balbir Singh <balbir@linux.vnet.ibm.com>
Reply-To: balbir@linux.vnet.ibm.com
Organization: IBM
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To: Hirokazu Takahashi <taka@valinux.co.jp>
CC: ryov@valinux.co.jp, kamezawa.hiroyu@jp.fujitsu.com,
       xen-devel@lists.xensource.com, containers@lists.linux-foundation.org,
       linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org,
       dm-devel@redhat.com, agk@sourceware.org, xemul@openvz.org,
       fernando@oss.ntt.co.jp
Subject: Re: [PATCH 4/7] bio-cgroup: Split the cgroup memory subsystem into
 two parts
References: <20080818103938.8b4e8bfa.kamezawa.hiroyu@jp.fujitsu.com> <20080819.122811.59660409.ryov@valinux.co.jp> <48AA4594.1000908@linux.vnet.ibm.com> <20080819.214635.70071441.taka@valinux.co.jp>
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Hirokazu Takahashi wrote:
> Hi,
> 
>>>> I'm now writing remove-lock-page-cgroup patches. it works well.
>>>> please wait for a while...
>>> I'm looking forward to those patches.
>>>
>>> By the way, I'm glad if memory-cgroup has a feature which can make a
>>> page_cgroup move between cgroups with small overhead. It makes
>>> bio-cgroup improve the accuracy of tracking down pages.
>> Page movement can be a very expensive operation and is proportional to the size
>> of the control group. I think movement should be an optional feature, if we ever
>> add it.
> 
> Yes, we should avoid moving pages as far as it is balanced fairly well
> between groups.
> 
> But I want to move pages between bio-cgoups in case it started charging
> quite a few I/O requests to a wrong bio-cgroup. I think it will be okay
> if pages moves between bio-cgroups, but they don't need to move between
> memory cgroups. I know the latter is really heavy and the effect seems
> to be so limited.

I was under the impression that you wanted memory-cgroup to provide the page
movement feature. That is not on the TODO list for us now.

-- 
	Balbir
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