From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: memcg: softlimit on internal nodes Date: Mon, 22 Apr 2013 08:57:44 -0700 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 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:sender:date:from:to:cc:subject:message-id:references :mime-version:content-type:content-disposition:in-reply-to :user-agent; bh=mTDcZhCpsj8bqtz4ALhM2M5nxXRpE0qdYlEIxBWabhY=; b=N/LGppTol8jAHS5yrnSOoMGxA+1AjrbCsc/jXZrhmSK2C0IJC6vpfIgM768m/SZ3qh Mb2JvpZRWP5TdEbeAPJhevX2sMxPRDp1oNNYZL9+Fx3DdLCCcyApTcUj44BerhhI+6qv 57uc7j+FJLENp95oimS9q4xY8Ca5R6ITjI6IWFvEXrPR6nJWphwGLRGMopMkUmz5ic43 7LC0TpCgQ5o6eFPh8NTFB7d4BGR1lLPAerynKsfxrOd0SxTn/G/MdZvy9ak32oLnwtk0 GbFnz0FySBSL76dijyvwK35MWJCslzXLB2KvRPvwzxNqO3izeIpqddCjg93lucBVF7eL uy8g== Content-Disposition: inline In-Reply-To: <20130422155703.GC12543-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Michal Hocko Cc: Johannes Weiner , Balbir Singh , KAMEZAWA Hiroyuki , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.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