Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932712Ab0LTQGq (ORCPT ); Mon, 20 Dec 2010 11:06:46 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125]:52538 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932702Ab0LTQGp (ORCPT ); Mon, 20 Dec 2010 11:06:45 -0500 X-Authority-Analysis: v=1.1 cv=+c36koQ5Dcj/1qolKHjtkYAGXvrVJRRiKMp+84F5sLg= c=1 sm=0 a=0YtosmEAv3sA:10 a=Q9fys5e9bTEA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=_NJRT24Ztekrb9NQwXEA:9 a=2K_R9xe4Yfpg1O09CSIs5DHWEAgA:4 a=PUjeQqilurYA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Subject: Re: [RFC PATCH 02/15] nohz_task: Avoid nohz task cpu as non-idle timer target From: Steven Rostedt To: Peter Zijlstra Cc: Frederic Weisbecker , LKML , Thomas Gleixner , "Paul E. McKenney" , Ingo Molnar , Lai Jiangshan , Andrew Morton , Anton Blanchard , Tim Pepper In-Reply-To: <1292860078.5021.6.camel@laptop> References: <1292858662-5650-1-git-send-email-fweisbec@gmail.com> <1292858662-5650-3-git-send-email-fweisbec@gmail.com> <1292860078.5021.6.camel@laptop> Content-Type: text/plain; charset="ISO-8859-15" Date: Mon, 20 Dec 2010 11:06:42 -0500 Message-ID: <1292861202.22905.23.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1035 Lines: 27 On Mon, 2010-12-20 at 16:47 +0100, Peter Zijlstra wrote: > On Mon, 2010-12-20 at 16:24 +0100, Frederic Weisbecker wrote: > > Unbound timers are preferably targeted for non idle cpu. If > > possible though, prioritize idle cpus over nohz task cpus, > > because the main point of nohz task is to avoid unnecessary > > timer interrupts. > > Oh is it? > > I'd very much expect the cpu that arms the timer to get the interrupt. I > mean, if the task doesn't want to get interrupted by timers, > _DON'T_USE_TIMERS_ to begin with. > > So no, don't much like this at all. I think this comes from other tasks on other CPUs that are using timers. Although, I'm not sure what causes an "unbound" timer to happen. I thought timers usually go off on the CPU that asked for it to go off. -- 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/