From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752705Ab3KSVt3 (ORCPT ); Tue, 19 Nov 2013 16:49:29 -0500 Received: from mga02.intel.com ([134.134.136.20]:48232 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751821Ab3KSVt2 (ORCPT ); Tue, 19 Nov 2013 16:49:28 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.93,535,1378882800"; d="scan'208";a="438080597" From: Andi Kleen To: Michal Hocko Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Expose sysctls for enabling slab/file_cache interleaving References: <1384822222-28795-1-git-send-email-andi@firstfloor.org> <20131119104203.GB18872@dhcp22.suse.cz> <20131119184200.GD29695@two.firstfloor.org> <20131119191135.GA8634@dhcp22.suse.cz> <20131119201333.GD19762@tassilo.jf.intel.com> <20131119212123.GA9339@dhcp22.suse.cz> Date: Tue, 19 Nov 2013 13:49:28 -0800 In-Reply-To: <20131119212123.GA9339@dhcp22.suse.cz> (Michal Hocko's message of "Tue, 19 Nov 2013 22:21:23 +0100") Message-ID: <87y54kvz87.fsf@tassilo.jf.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Michal Hocko writes: > > Another option would be to use sysctl values for the top cpuset as a > default. But then why not just do it manually without sysctl? I want to provide an alternative to having to use cpusets to use this, that is actually usable for normal people. Also this is really a global setting in my mind. > If you create a cpuset and explicitly disable spreading then you would > be quite surprised that your process gets pages from all nodes, no? If I enable it globally using a sysctl I would be quite surprised if some cpuset can override it. That argument is equally valid :-) The user configured an inconsistent configuration, and the kernel has to make a decision somehow. In the end it is arbitary, but not having to check the cpuset here is a lot cheaper, so I prefer the "sysctl has priority" option. Could EINVAL the cpuset setting when the sysctl is set though (but it's difficult to do the other way round). -Andi -- ak@linux.intel.com -- Speaking for myself only