From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755464AbcDGI2X (ORCPT ); Thu, 7 Apr 2016 04:28:23 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:53659 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751387AbcDGI2R (ORCPT ); Thu, 7 Apr 2016 04:28:17 -0400 Date: Thu, 7 Apr 2016 10:28:10 +0200 From: Peter Zijlstra To: Johannes Weiner Cc: Tejun Heo , torvalds@linux-foundation.org, akpm@linux-foundation.org, mingo@redhat.com, lizefan@huawei.com, pjt@google.com, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-api@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCHSET RFC cgroup/for-4.6] cgroup, sched: implement resource group and PRIO_RGRP Message-ID: <20160407082810.GN3430@twins.programming.kicks-ass.net> References: <1457710888-31182-1-git-send-email-tj@kernel.org> <20160314113013.GM6344@twins.programming.kicks-ass.net> <20160406155830.GI24661@htj.duckdns.org> <20160407064549.GH3430@twins.programming.kicks-ass.net> <20160407073547.GA12560@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160407073547.GA12560@cmpxchg.org> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 07, 2016 at 03:35:47AM -0400, Johannes Weiner wrote: > There was a lot of back and forth whether we should add a second set > of knobs just to control the local tasks separately from the subtree, > but ended up concluding that the situation can be expressed more > clearly by creating dedicated leaf subgroups for stuff like management > software and launchers instead, so that their memory pools/LRUs are > clearly delineated from other groups and seperately controllable. And > we couldn't think of any meaningful configuration that could not be > expressed in that scheme. I mean, it's the same thing, right? No, not the same. R / | \ t1 t2 A / \ t3 t4 Is fundamentally different from: R / \ L A / \ / \ t1 t2 t3 t4 Because if in the first hierarchy you add a task (t5) to R, all of its A will run at 1/4th of total bandwidth where before it had 1/3rd, whereas with the second example, if you add our t5 to L, A doesn't get any less bandwidth. Please pull your collective heads out of the systemd arse and start thinking. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCHSET RFC cgroup/for-4.6] cgroup, sched: implement resource group and PRIO_RGRP Date: Thu, 7 Apr 2016 10:28:10 +0200 Message-ID: <20160407082810.GN3430@twins.programming.kicks-ass.net> References: <1457710888-31182-1-git-send-email-tj@kernel.org> <20160314113013.GM6344@twins.programming.kicks-ass.net> <20160406155830.GI24661@htj.duckdns.org> <20160407064549.GH3430@twins.programming.kicks-ass.net> <20160407073547.GA12560@cmpxchg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20160407073547.GA12560-druUgvl0LCNAfugRpC6u6w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Johannes Weiner Cc: Tejun Heo , torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, pjt-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-team-b10kYP2dOMg@public.gmane.org List-Id: linux-api@vger.kernel.org On Thu, Apr 07, 2016 at 03:35:47AM -0400, Johannes Weiner wrote: > There was a lot of back and forth whether we should add a second set > of knobs just to control the local tasks separately from the subtree, > but ended up concluding that the situation can be expressed more > clearly by creating dedicated leaf subgroups for stuff like management > software and launchers instead, so that their memory pools/LRUs are > clearly delineated from other groups and seperately controllable. And > we couldn't think of any meaningful configuration that could not be > expressed in that scheme. I mean, it's the same thing, right? No, not the same. R / | \ t1 t2 A / \ t3 t4 Is fundamentally different from: R / \ L A / \ / \ t1 t2 t3 t4 Because if in the first hierarchy you add a task (t5) to R, all of its A will run at 1/4th of total bandwidth where before it had 1/3rd, whereas with the second example, if you add our t5 to L, A doesn't get any less bandwidth. Please pull your collective heads out of the systemd arse and start thinking.