Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753184AbaKDMwq (ORCPT ); Tue, 4 Nov 2014 07:52:46 -0500 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.227]:58838 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750866AbaKDMwp (ORCPT ); Tue, 4 Nov 2014 07:52:45 -0500 Date: Tue, 4 Nov 2014 07:52:37 -0500 From: Steven Rostedt To: "pang.xunlei" Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Juri Lelli Subject: Re: [PATCH v2 2/6] sched/rt: Optimize select_task_rq_rt() for non-RT curr task Message-ID: <20141104075237.4eb9b5e6@gandalf.local.home> In-Reply-To: <1415099585-31174-2-git-send-email-pang.xunlei@linaro.org> References: <1415099585-31174-1-git-send-email-pang.xunlei@linaro.org> <1415099585-31174-2-git-send-email-pang.xunlei@linaro.org> X-Mailer: Claws Mail 3.10.1 (GTK+ 2.24.25; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.142:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 4 Nov 2014 19:13:01 +0800 "pang.xunlei" wrote: > When selecting the cpu for a waking RT task, if curr is a non-RT > task which is bound only on this cpu, then we can give it a chance > to select a different cpu(definitely an idle cpu if existing) for > the RT task to avoid curr starving. Absolutely not! An RT task doesn't give a crap if a non RT task is bound to a CPU or not. We are not going to migrate an RT task to be nice to a bounded non-RT task. Migration is not cheap. It causes cache misses and TLB flushes. This is not something that should be taken lightly. Nack -- Steve -- 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/