Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932827Ab3FQLtu (ORCPT ); Mon, 17 Jun 2013 07:49:50 -0400 Received: from www.linutronix.de ([62.245.132.108]:34862 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932727Ab3FQLts (ORCPT ); Mon, 17 Jun 2013 07:49:48 -0400 Message-ID: <51BEF7DA.700@linutronix.de> Date: Mon, 17 Jun 2013 13:49:46 +0200 From: Sebastian Andrzej Siewior User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130518 Icedove/17.0.5 MIME-Version: 1.0 To: Zhao Chenhui CC: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, leoli@freescale.com, scottwood@freescale.com, Priyanka.Jain@freescale.com Subject: Re: [PATCH][RFC] kernel/cpu: do not change the cpus_allowed of the current task when unplugging cpus References: <1368699439-13034-1-git-send-email-chenhui.zhao@freescale.com> <20130607090543.GD10280@linutronix.de> <20130609095942.GA8548@localhost.localdomain> <20130614152917.GA8597@linutronix.de> <20130617104832.GA20410@localhost.localdomain> In-Reply-To: <20130617104832.GA20410@localhost.localdomain> X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1027 Lines: 27 On 06/17/2013 12:48 PM, Zhao Chenhui wrote: > I don't think it is necessary to change the mask. migration_call() invoked by > the cpu notify "CPU_DYING" will remove all running tasks from the dying cpu. > Even if the current task is running on the dying cpu, it will be transfered > to another online cpu. I had here hiccups if the task was running on the CPU which should go down. > I guess that changing the mask benefits the latency of the system. > Please correct me. I don't get this. Lets say your system has CPUs 0-15 and you pin your application to CPU0. After this application brings CPU15 down it is allowed to run on CPUs 0-14. This is wrong and has been corrected. The CPU down mechanism should not affected CPU mask of the application. > > -Chenhui > Sebastian -- 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/