From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx190.postini.com [74.125.245.190]) by kanga.kvack.org (Postfix) with SMTP id E63E26B0033 for ; Mon, 22 Apr 2013 11:57:48 -0400 (EDT) Received: by mail-pd0-f172.google.com with SMTP id 4so686675pdd.31 for ; Mon, 22 Apr 2013 08:57:48 -0700 (PDT) Date: Mon, 22 Apr 2013 08:57:44 -0700 From: Tejun Heo Subject: Re: memcg: softlimit on internal nodes Message-ID: <20130422155744.GD12543@htj.dyndns.org> References: <20130420002620.GA17179@mtj.dyndns.org> <20130420031611.GA4695@dhcp22.suse.cz> <20130421022321.GE19097@mtj.dyndns.org> <20130421124554.GA8473@dhcp22.suse.cz> <20130422043939.GB25089@mtj.dyndns.org> <20130422151908.GF18286@dhcp22.suse.cz> <20130422155703.GC12543@htj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130422155703.GC12543@htj.dyndns.org> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Johannes Weiner , Balbir Singh , KAMEZAWA Hiroyuki , cgroups@vger.kernel.org, linux-mm@kvack.org, Hugh Dickins , Ying Han , Glauber Costa , Michel Lespinasse , Greg Thelen On Mon, Apr 22, 2013 at 08:57:03AM -0700, Tejun Heo wrote: > On Mon, Apr 22, 2013 at 05:19:08PM +0200, Michal Hocko wrote: > > We can try to be clever during the outside pressure and prefer > > reclaiming over soft limit groups first. Which we used to do and will > > do after rework as well. As a side effect of that a properly designed > > hierachy with opt-in soft limited groups can actually accomplish some > > isolation is a nice side effect but no _guarantee_. > > Okay, so it *is* a soft limit. Good. If so, a subtree going over the > limit of course forces reclaim on its children even though their > individual configs aren't over limit. It's exactly the same as > hardlimit. There doesn't need to be any difference and there's > nothing questionable or interesting about it. > > Also, then, a cgroup which has been configured explicitly shouldn't be ^ not > disadvantaged compared to a cgroup with a limit configured. ie. the > current behavior of giving maximum to the knob on creation is the > correct one. The knob should create *extra* pressure. It shouldn't > lessen the pressure. When populated weith other cgroups with limits > configured, it would change the relative pressure felt by each but in > general it's a limiting mechanism not an isolation one. I think the > bulk of confusion is coming from this, so please make that abundantly > clear. > > And, if people want a mechanism for isolation / lessening of pressure, > which looks like a valid use case to me, add another knob for that > which is prioritized under both hard and soft limits. That is the > only sensible way to do it. > > Alright, no complaint anymore. Thanks. > > -- > tejun -- tejun -- 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