From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 5EC836008D8 for ; Tue, 24 Aug 2010 03:19:26 -0400 (EDT) From: Greg Thelen Subject: Re: [PATCH 1/5] cgroup: ID notification call back References: <20100820185552.426ff12e.kamezawa.hiroyu@jp.fujitsu.com> <20100820185816.1dbcd53a.kamezawa.hiroyu@jp.fujitsu.com> Date: Tue, 24 Aug 2010 00:19:01 -0700 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: linux-mm@kvack.org, "nishimura@mxp.nes.nec.co.jp" , "balbir@linux.vnet.ibm.com" , m-ikeda@ds.jp.nec.com, "akpm@linux-foundation.org" , "linux-kernel@vger.kernel.org" , kamezawa.hiroyuki@gmail.com, "menage@google.com" , "lizf@cn.fujitsu.com" List-ID: KAMEZAWA Hiroyuki writes: > CC'ed to Paul Menage and Li Zefan. > == > From: KAMEZAWA Hiroyuki > > When cgroup subsystem use ID (ss->use_id==1), each css's ID is assigned > after successful call of ->create(). css_ID is tightly coupled with > css struct itself but it is allocated by ->create() call, IOW, > per-subsystem special allocations. > > To know css_id before creation, this patch adds id_attached() callback. > after css_ID allocation. This will be used by memory cgroup's quick lookup > routine. > > Maybe you can think of other implementations as > - pass ID to ->create() > or > - add post_create() > etc... > But when considering dirtiness of codes, this straightforward patch seems > good to me. If someone wants post_create(), this patch can be replaced. > > Changelog: 20100820 > - new approarch. > > Signed-off-by: KAMEZAWA Hiroyuki > --- > Documentation/cgroups/cgroups.txt | 10 ++++++++++ > include/linux/cgroup.h | 1 + > kernel/cgroup.c | 5 ++++- > 3 files changed, 15 insertions(+), 1 deletion(-) > > Index: mmotm-0811/Documentation/cgroups/cgroups.txt > =================================================================== > --- mmotm-0811.orig/Documentation/cgroups/cgroups.txt > +++ mmotm-0811/Documentation/cgroups/cgroups.txt > @@ -621,6 +621,16 @@ 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 id_attached(struct cgroup_subsys *ss, struct cgroup *root) > +(cgroup_mutex and ss->hierarchy_mutex held by caller) > +(called only when ss->use_id=1) > + > +Called when css_id is attached to css. Because css_id is assigned > +against "css", css_id is not available until ->create() is called. > +If subsystem wants to make use of ID at createtion time, use Minor spelling correction: s/createtion/creation/ > +this handler. This handler will be called after css_id is assigned > +to css. Not necessary to be implemented in usual(see memcontrol.c) Maybe this sounds better? "This handler is not usually needed. See memcontrol.c for an example." > + > 4. Questions > ============ > > Index: mmotm-0811/include/linux/cgroup.h > =================================================================== > --- mmotm-0811.orig/include/linux/cgroup.h > +++ mmotm-0811/include/linux/cgroup.h > @@ -475,6 +475,7 @@ struct cgroup_subsys { > struct cgroup *cgrp); > void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp); > void (*bind)(struct cgroup_subsys *ss, struct cgroup *root); > + void (*id_attached)(struct cgroup_subsys *ss, struct cgroup *cgrp); > > int subsys_id; > int active; > Index: mmotm-0811/kernel/cgroup.c > =================================================================== > --- mmotm-0811.orig/kernel/cgroup.c > +++ mmotm-0811/kernel/cgroup.c > @@ -4618,6 +4618,8 @@ static int __init_or_module cgroup_init_ > newid->stack[0] = newid->id; > newid->css = rootcss; > rootcss->id = newid; > + if (ss->id_attached) > + ss->id_attached(ss, dummytop); > return 0; > } > > @@ -4646,7 +4648,8 @@ static int alloc_css_id(struct cgroup_su > * see cgroup_populate_dir() > */ > rcu_assign_pointer(child_css->id, child_id); > - > + if (ss->id_attached) > + ss->id_attached(ss, child); > return 0; > } > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org