Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753200Ab2JBJTT (ORCPT ); Tue, 2 Oct 2012 05:19:19 -0400 Received: from mx2.parallels.com ([64.131.90.16]:55465 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752738Ab2JBJTR (ORCPT ); Tue, 2 Oct 2012 05:19:17 -0400 Message-ID: <506AB0BF.9030400@parallels.com> Date: Tue, 2 Oct 2012 13:15:43 +0400 From: Glauber Costa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 MIME-Version: 1.0 To: Michal Hocko CC: , , , , Peter Zijlstra , Kamezawa Hiroyuki , Johannes Weiner , Mel Gorman , Andrew Morton Subject: Re: [RFC 1/4] memcg: provide root figures from system totals References: <1348563173-8952-1-git-send-email-glommer@parallels.com> <1348563173-8952-2-git-send-email-glommer@parallels.com> <20121001170046.GC24860@dhcp22.suse.cz> In-Reply-To: <20121001170046.GC24860@dhcp22.suse.cz> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1145 Lines: 23 On 10/01/2012 09:00 PM, Michal Hocko wrote: > On Tue 25-09-12 12:52:50, Glauber Costa wrote: >> > For the root memcg, there is no need to rely on the res_counters. > This is true only if there are no children groups but once there is at > least one we have to move global statistics into root res_counter and > start using it since then. This is a tricky part because it has to be > done atomically so that we do not miss anything. > Why can't we shortcut it all the time? It makes a lot of sense to use the root cgroup as the sum of everything, IOW, global counters. Otherwise you are left in a situation where you had global statistics, and all of a sudden, when a group is created, you start having just a subset of that, excluding the tasks in root. If we can always assume root will have the sum of *all* tasks, including the ones in root, we should never need to rely on root res_counters. -- 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/