Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752669Ab3HAFP1 (ORCPT ); Thu, 1 Aug 2013 01:15:27 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:58883 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751900Ab3HAFPZ (ORCPT ); Thu, 1 Aug 2013 01:15:25 -0400 Date: Thu, 1 Aug 2013 10:43:27 +0530 From: Srikar Dronamraju To: Mel Gorman 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: <20130801051327.GF4880@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <1373901620-2021-1-git-send-email-mgorman@suse.de> <1373901620-2021-18-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1373901620-2021-18-git-send-email-mgorman@suse.de> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13080105-3620-0000-0000-000003C5C99F Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1251 Lines: 30 * 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()? 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? > the conditions are not right. This patch will check at NUMA hinting fault > time if another attempt should be made to migrate the task. It will only > make an attempt once every five seconds. > > Signed-off-by: Mel Gorman -- Thanks and Regards Srikar Dronamraju -- 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/