From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx197.postini.com [74.125.245.197]) by kanga.kvack.org (Postfix) with SMTP id 74ABE6B005A for ; Tue, 26 Jun 2012 11:27:14 -0400 (EDT) Date: Tue, 26 Jun 2012 17:27:11 +0200 From: Michal Hocko Subject: Re: [PATCH] memcg: first step towards hierarchical controller Message-ID: <20120626152711.GF9566@tiehlicka.suse.cz> References: <1340717428-9009-1-git-send-email-glommer@parallels.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1340717428-9009-1-git-send-email-glommer@parallels.com> Sender: owner-linux-mm@kvack.org List-ID: To: Glauber Costa Cc: cgroups@vger.kernel.org, linux-mm@kvack.org, Peter Zijlstra , Kamezawa Hiroyuki , Johannes Weiner , Tejun Heo On Tue 26-06-12 17:30:28, Glauber Costa wrote: > Okay, so after recent discussions, I am proposing the following > patch. It won't remove hierarchy, or anything like that. Just default > to true in the root cgroup, and print a warning once if you try > to set it back to 0. > > I am not adding it to feature-removal-schedule.txt because I don't > view it as a consensus. Rather, changing the default would allow us > to give it a time around in the open, and see if people complain > and what we can learn about that. > > Signed-off-by: Glauber Costa > CC: Michal Hocko > CC: Kamezawa Hiroyuki > CC: Johannes Weiner > CC: Tejun Heo > --- > mm/memcontrol.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 9e710bc..037ddd4 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -3949,6 +3949,8 @@ static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft, > if (memcg->use_hierarchy == val) > goto out; > > + WARN_ONCE((!parent_memcg && memcg->use_hierarchy && val == false), > + "Non-hierarchical memcg is considered for deprecation"); > /* > * If parent's use_hierarchy is set, we can't make any modifications > * in the child subtrees. If it is unset, then the change can > @@ -5175,6 +5177,7 @@ mem_cgroup_create(struct cgroup *cont) > INIT_WORK(&stock->work, drain_local_stock); > } > hotcpu_notifier(memcg_cpu_hotplug_callback, 0); > + memcg->use_hierarchy = true; So the only way to disable hierarchies is to do it on the root first (before any children exist) and then start creating your groups? I think it will be much safer if we could enable it to the first floor under the root - I know hackish - but I guess that most users don't set anything in the root cgroup (most of the time it's EINVAL anyway) and only set up groups they are creating. Anyway, I guess we can give this approach a try. > } else { > parent = mem_cgroup_from_cont(cont->parent); > memcg->use_hierarchy = parent->use_hierarchy; Thanks -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- 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