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Message-ID: <6599ad830803162003u63589715i7d06c8b271c22160@mail.gmail.com>
Date: Mon, 17 Mar 2008 11:03:49 +0800
From: "Paul Menage" <menage@google.com>
To: balbir@linux.vnet.ibm.com
Subject: Re: [RFC][2/3] Account and control virtual address space allocations
Cc: linux-mm@kvack.org, "Hugh Dickins" <hugh@veritas.com>,
       "Sudhir Kumar" <skumar@linux.vnet.ibm.com>,
       "YAMAMOTO Takashi" <yamamoto@valinux.co.jp>, lizf@cn.fujitsu.com,
       linux-kernel@vger.kernel.org, taka@valinux.co.jp,
       "David Rientjes" <rientjes@google.com>,
       "Pavel Emelianov" <xemul@openvz.org>,
       "Andrew Morton" <akpm@linux-foundation.org>,
       "KAMEZAWA Hiroyuki" <kamezawa.hiroyu@jp.fujitsu.com>
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On Mon, Mar 17, 2008 at 10:57 AM, Balbir Singh
<balbir@linux.vnet.ibm.com> wrote:
>
>  1. We want to be able to support hierarchial accounting and control

>  2. We want to track usage of the root cgroup and report it back to the user

What use cases do you have for that?

>  3. We don't want to treat the root cgroup as a special case.

Why? It is a special case, in that in a lot of machines there's only
going to be the root cgroup, and the subsystem won't be mounted. So in
those cases, paying any overhead is a cost without a benefit.

Alternatively, how about you skip tracking virtual address space
changes if the virtual address cgroup isn't mounted on any hierarchy?
When you mount it, you can do a pass across all mms and set the root
cgroup usage to their total.

Paul