Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753360Ab0G1Ck0 (ORCPT ); Tue, 27 Jul 2010 22:40:26 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:45940 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751879Ab0G1CkZ (ORCPT ); Tue, 27 Jul 2010 22:40:25 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Wed, 28 Jul 2010 11:35:29 +0900 From: KAMEZAWA Hiroyuki To: Vivek Goyal Cc: "linux-mm@kvack.org" , "nishimura@mxp.nes.nec.co.jp" , "balbir@linux.vnet.ibm.com" , gthelen@google.com, m-ikeda@ds.jp.nec.com, "akpm@linux-foundation.org" , "linux-kernel@vger.kernel.org" Subject: Re: [RFC][PATCH 2/7][memcg] cgroup arbitarary ID allocation Message-Id: <20100728113529.f086716d.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100728023027.GD12642@redhat.com> References: <20100727165155.8b458b7f.kamezawa.hiroyu@jp.fujitsu.com> <20100727165417.dacbe199.kamezawa.hiroyu@jp.fujitsu.com> <20100728023027.GD12642@redhat.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.0.3 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2127 Lines: 60 On Tue, 27 Jul 2010 22:30:27 -0400 Vivek Goyal wrote: > > Index: mmotm-2.6.35-0719/Documentation/cgroups/cgroups.txt > > =================================================================== > > --- mmotm-2.6.35-0719.orig/Documentation/cgroups/cgroups.txt > > +++ mmotm-2.6.35-0719/Documentation/cgroups/cgroups.txt > > @@ -621,6 +621,15 @@ and root cgroup. Currently this will onl > > the default hierarchy (which never has sub-cgroups) and a hierarchy > > that is being created/destroyed (and hence has no sub-cgroups). > > > > +void custom_id(struct cgroup_subsys *ss, struct cgroup *cgrp) > > + > > +Called at assigning a new ID to cgroup subsystem state struct. This > > +is called when ss->use_id == true. If this function is not provided, > > +a new ID is automatically assigned. If you enable ss->use_id, > > +you can use css_lookup() and css_get_next() to access "css" objects > > +via IDs. > > + > > Couple of lines to explain why a subsystem would like to assign its > own ids and not be happy with generic cgroup assigned id be helpful. > In this case, I think you are using this id as index into array > and want to control the index, hence you seem to be doing it. > > But I am not sure again why do you want to control index? > Now, the subsystem allocation/id-allocation order is ->create() alloc_id. Otherwise "id" of memory cgroup is just determined by the place in virtual-indexed array. As memcg = mem_cgroup_base + id This "id" is determined at create(). If "id" is determined regardless of memory cgroup's placement, it's of no use. My original design of css_id() allocates id in create() but it was moved to generic part. So, this is expected change in my plan. We have 2 choices. id = alloc_id() create(id) or this patch. Both are okay for me. But alloc id before create() may add some ugly rollback. Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/