Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753248Ab3IWP7N (ORCPT ); Mon, 23 Sep 2013 11:59:13 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:14047 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752773Ab3IWP7L (ORCPT ); Mon, 23 Sep 2013 11:59:11 -0400 X-Authority-Analysis: v=2.0 cv=fJG7LOme c=1 sm=0 a=Sro2XwOs0tJUSHxCKfOySw==:17 a=Drc5e87SC40A:10 a=6uerBSPhkSsA:10 a=5SG0PmZfjMsA:10 a=kj9zAlcOel0A:10 a=meVymXHHAAAA:8 a=KGjhK52YXX0A:10 a=rzOjJkEkrDcA:10 a=JfrnYn6hAAAA:8 a=1OywPWlEJrYYbX3kbn8A:9 a=CjuIK1q_8ugA:10 a=3Rfx1nUSh_UA:10 a=Sro2XwOs0tJUSHxCKfOySw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 67.255.60.225 Date: Mon, 23 Sep 2013 11:59:08 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: Mel Gorman , Rik van Riel , Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML , Oleg Nesterov , Paul McKenney , Thomas Gleixner Subject: Re: [PATCH] hotplug: Optimize {get,put}_online_cpus() Message-ID: <20130923115908.6e710d29@gandalf.local.home> In-Reply-To: <20130923152223.GZ9326@twins.programming.kicks-ass.net> References: <1378805550-29949-1-git-send-email-mgorman@suse.de> <1378805550-29949-38-git-send-email-mgorman@suse.de> <20130917143003.GA29354@twins.programming.kicks-ass.net> <20130917162050.GK22421@suse.de> <20130917164505.GG12926@twins.programming.kicks-ass.net> <20130918154939.GZ26785@twins.programming.kicks-ass.net> <20130919143241.GB26785@twins.programming.kicks-ass.net> <20130923105017.030e0aef@gandalf.local.home> <20130923145446.GX9326@twins.programming.kicks-ass.net> <20130923111303.04b99db8@gandalf.local.home> <20130923152223.GZ9326@twins.programming.kicks-ass.net> X-Mailer: Claws Mail 3.9.2 (GTK+ 2.24.20; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 732 Lines: 19 On Mon, 23 Sep 2013 17:22:23 +0200 Peter Zijlstra wrote: > Still no point in using srcu for this; preempt_disable + > synchronize_sched() is similar and much faster -- its the rcu_sched > equivalent of what you propose. To be honest, I sent this out last week and it somehow got trashed by my laptop and connecting to my smtp server. Where the last version of your patch still had the memory barrier ;-) So yeah, a true synchronize_sched() is better. -- 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/