From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH V2] cpuset: Add knob to make allowed masks hotplug invariant on legacy hierarchy Date: Sat, 11 Apr 2015 15:42:02 +0200 Message-ID: <20150411134202.GS27490@worktop.programming.kicks-ass.net> References: <20150410141118.11284.36206.stgit@preeti.in.ibm.com> <20150411083537.GR27490@worktop.programming.kicks-ass.net> <552903BC.3050103@linux.vnet.ibm.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <552903BC.3050103-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Preeti U Murthy Cc: tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, svaidy-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, nacc-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, rjw-LthD3rsA81gm4RdzfppkhA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, anton-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org, bharata-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org On Sat, Apr 11, 2015 at 04:51:32PM +0530, Preeti U Murthy wrote: > On 04/11/2015 02:05 PM, Peter Zijlstra wrote: > > On Fri, Apr 10, 2015 at 07:41:52PM +0530, Preeti U Murthy wrote: > > What you've not explained is why you can use this knob but not use the > > other new mode? > > It is claimed that the existing software which work with the legacy > hierarchy break when cgroups are mounted on the default hierarchy due to > poor backward compatibility. I will include this point in the changelog. But you don't have to mount the new thing in the unified hierarchy nonsense. You can mount if separate but still with the new semantics. Unless of course system disease disallows this, but that's not a kernel problem. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755490AbbDKNmL (ORCPT ); Sat, 11 Apr 2015 09:42:11 -0400 Received: from casper.infradead.org ([85.118.1.10]:39523 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754947AbbDKNmJ (ORCPT ); Sat, 11 Apr 2015 09:42:09 -0400 Date: Sat, 11 Apr 2015 15:42:02 +0200 From: Peter Zijlstra To: Preeti U Murthy Cc: tj@kernel.org, svaidy@linux.vnet.ibm.com, nacc@linux.vnet.ibm.com, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, lizefan@huawei.com, anton@samba.org, bharata@linux.vnet.ibm.com, cgroups@vger.kernel.org, paulmck@linux.vnet.ibm.com, mingo@kernel.org, serge@hallyn.com Subject: Re: [PATCH V2] cpuset: Add knob to make allowed masks hotplug invariant on legacy hierarchy Message-ID: <20150411134202.GS27490@worktop.programming.kicks-ass.net> References: <20150410141118.11284.36206.stgit@preeti.in.ibm.com> <20150411083537.GR27490@worktop.programming.kicks-ass.net> <552903BC.3050103@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <552903BC.3050103@linux.vnet.ibm.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 11, 2015 at 04:51:32PM +0530, Preeti U Murthy wrote: > On 04/11/2015 02:05 PM, Peter Zijlstra wrote: > > On Fri, Apr 10, 2015 at 07:41:52PM +0530, Preeti U Murthy wrote: > > What you've not explained is why you can use this knob but not use the > > other new mode? > > It is claimed that the existing software which work with the legacy > hierarchy break when cgroups are mounted on the default hierarchy due to > poor backward compatibility. I will include this point in the changelog. But you don't have to mount the new thing in the unified hierarchy nonsense. You can mount if separate but still with the new semantics. Unless of course system disease disallows this, but that's not a kernel problem.