From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755293AbcDGIIx (ORCPT ); Thu, 7 Apr 2016 04:08:53 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:44609 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751387AbcDGIIr (ORCPT ); Thu, 7 Apr 2016 04:08:47 -0400 Date: Thu, 7 Apr 2016 10:08:33 +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: <20160407080833.GK3430@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: > On Thu, Apr 07, 2016 at 08:45:49AM +0200, Peter Zijlstra wrote: > > So I recently got made aware of the fact that cgroupv2 doesn't allow > > tasks to be associated with !leaf cgroups, this is yet another > > capability of cpu-cgroup you've destroyed. > > May I ask how you are using that? _I_ use a kernel with CONFIG_CGROUPS=n (yes really). But seriously? You have to ask? The root cgroup is per definition not a leaf, and all tasks start life there, and some cannot be ever moved out. Therefore _everybody_ uses this. > The behavior for tasks in !leaf groups was fairly inconsistent across > controllers because they all did different things, or didn't handle it > at all. Then they're all bloody broken, because fully hierarchical was an early requirement for cgroups; I know, because I had to throw away many days of work and start over with cgroup support when they did that. > So it was a nice cleanup for the memory controller and I believe the > IO controller as well. I'd be curious how it'd be a problem for CPU? The full hierarchy took years to make work and is fully ingrained with how the thing words, changing it isn't going to be nice or easy. So sure, go with a lowest common denominator, instead of fixing shit, yay for progress :/ 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 10:08:33 +0200 Message-ID: <20160407080833.GK3430@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: linux-api-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: > On Thu, Apr 07, 2016 at 08:45:49AM +0200, Peter Zijlstra wrote: > > So I recently got made aware of the fact that cgroupv2 doesn't allow > > tasks to be associated with !leaf cgroups, this is yet another > > capability of cpu-cgroup you've destroyed. > > May I ask how you are using that? _I_ use a kernel with CONFIG_CGROUPS=n (yes really). But seriously? You have to ask? The root cgroup is per definition not a leaf, and all tasks start life there, and some cannot be ever moved out. Therefore _everybody_ uses this. > The behavior for tasks in !leaf groups was fairly inconsistent across > controllers because they all did different things, or didn't handle it > at all. Then they're all bloody broken, because fully hierarchical was an early requirement for cgroups; I know, because I had to throw away many days of work and start over with cgroup support when they did that. > So it was a nice cleanup for the memory controller and I believe the > IO controller as well. I'd be curious how it'd be a problem for CPU? The full hierarchy took years to make work and is fully ingrained with how the thing words, changing it isn't going to be nice or easy. So sure, go with a lowest common denominator, instead of fixing shit, yay for progress :/