Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755366AbaFKMVA (ORCPT ); Wed, 11 Jun 2014 08:21:00 -0400 Received: from forward3m.mail.yandex.net ([37.140.138.3]:37416 "EHLO forward3m.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751328AbaFKMU7 (ORCPT ); Wed, 11 Jun 2014 08:20:59 -0400 From: Kirill Tkhai To: Srikar Dronamraju Cc: "linux-kernel@vger.kernel.org" , Peter Zijlstra , Ingo Molnar , Tkhai Kirill In-Reply-To: <20140611112411.GA21191@linux.vnet.ibm.com> References: <20140611093417.27807.2288.stgit@tkhai> <1402480330.32126.14.camel@tkhai> <20140611112411.GA21191@linux.vnet.ibm.com> Subject: Re: [PATCH 1/2] sched: Rework migrate_tasks() MIME-Version: 1.0 Message-Id: <3732251402489254@web2m.yandex.ru> X-Mailer: Yamail [ http://yandex.ru ] 5.0 Date: Wed, 11 Jun 2014 16:20:54 +0400 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=koi8-r Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 11.06.2014, 15:24, "Srikar Dronamraju" : > * Kirill Tkhai [2014-06-11 13:52:10]: >> ?Currently migrate_tasks() skips throttled tasks, >> ?because they are not pickable by pick_next_task(). > > Before migrate_tasks() is called, we do call set_rq_offline(), in > migration_call(). > > Shouldnt this take care of unthrottling the tasks and making sure that > they can be picked by pick_next_task(). If we do this separate for every class, we'll have to do this 3 times. Furthermore, deadline class does not have a list of throttled tasks. So we'll have to the same as I did: to lock tasklist_lock and to iterate throw all of the tasks in the system just to found deadline tasks. >> ?These tasks stay on dead cpu even after they >> ?becomes unthrottled. They are not schedulable >> ?till user manually changes their affinity or till >> ?cpu becomes alive again. > > If we are still seeing tasks not being picked by pick_next_task(), then > can it probably mean that rq->rd was NULL? Unthrottle functions dl_task_timer() and unthrottle_cfs_rq() put tasks and queues back. They do not look at rq->rd. do_sched_rt_period_timer() does not unthrottle dead queue at all (they are excluded from rd). Thanks, Kirill -- 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/