From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751868AbdBAIxf (ORCPT ); Wed, 1 Feb 2017 03:53:35 -0500 Received: from mx2.suse.de ([195.135.220.15]:33078 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751560AbdBAIxd (ORCPT ); Wed, 1 Feb 2017 03:53:33 -0500 Date: Wed, 1 Feb 2017 09:53:26 +0100 From: Michal Hocko To: Anshuman Khandual Cc: Mel Gorman , linux-kernel@vger.kernel.org, linux-mm@kvack.org, vbabka@suse.cz, minchan@kernel.org, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, srikar@linux.vnet.ibm.com, haren@linux.vnet.ibm.com, jglisse@redhat.com, dave.hansen@intel.com, dan.j.williams@intel.com Subject: Re: [RFC] cpuset: Enable changing of top_cpuset's mems_allowed nodemask Message-ID: <20170201085326.GE5977@dhcp22.suse.cz> References: <20170130203003.dm2ydoi3e6cbbwcj@suse.de> <20170131142237.27097-1-khandual@linux.vnet.ibm.com> <20170131160029.ubt6fvw6oh2fgxpd@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 01-02-17 13:01:24, Anshuman Khandual wrote: [...] > More importantly it also extends the cpuset memory restriction feature > to the logical completion without adding any regressions for the > existing use cases. Then why not do this ? Does it add any overhead ? Maybe it doesn't add any overhead but it just breaks the cgroups expectation that the root cgroup covers the full resource set. No cgroup controller allows to set limits on the root cgroup. So all this looks like an abuse of the interface. I haven't read the full series yet but this particular change looks like a nogo to me. -- Michal Hocko SUSE Labs