Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757095Ab3HAPqK (ORCPT ); Thu, 1 Aug 2013 11:46:10 -0400 Received: from cantor2.suse.de ([195.135.220.15]:37601 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756585Ab3HAPqI (ORCPT ); Thu, 1 Aug 2013 11:46:08 -0400 Date: Thu, 1 Aug 2013 16:46:04 +0100 From: Mel Gorman To: Srikar Dronamraju Cc: Peter Zijlstra , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML Subject: Re: [PATCH 17/18] sched: Retry migration of tasks to CPU on a preferred node Message-ID: <20130801154604.GF2296@suse.de> References: <1373901620-2021-1-git-send-email-mgorman@suse.de> <1373901620-2021-18-git-send-email-mgorman@suse.de> <20130801051327.GF4880@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20130801051327.GF4880@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1188 Lines: 31 On Thu, Aug 01, 2013 at 10:43:27AM +0530, Srikar Dronamraju wrote: > * Mel Gorman [2013-07-15 16:20:19]: > > > When a preferred node is selected for a tasks there is an attempt to migrate > > the task to a CPU there. This may fail in which case the task will only > > migrate if the active load balancer takes action. This may never happen if > > Apart from load imbalance or heavily loaded cpus on the preferred node, > what could be the other reasons for migration failure with > migrate_task_to()? These were the reasons I expected that migration might fail. > I see it almost similar to active load balance except > for pushing instead of pulling tasks. > > If load imbalance is the only reason, do we need to retry? If the task > is really so attached to memory on that node, shouldn't we getting > task_numa_placement hit before the next 5 seconds? > Depends on the PTE scanning rate. -- Mel Gorman SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/