From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx166.postini.com [74.125.245.166]) by kanga.kvack.org (Postfix) with SMTP id B1E676B13F1 for ; Wed, 1 Feb 2012 15:13:57 -0500 (EST) Received: from /spool/local by e39.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 1 Feb 2012 13:13:56 -0700 Received: from d03relay03.boulder.ibm.com (d03relay03.boulder.ibm.com [9.17.195.228]) by d03dlp02.boulder.ibm.com (Postfix) with ESMTP id E832E3E40048 for ; Wed, 1 Feb 2012 13:13:45 -0700 (MST) Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d03relay03.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q11KDdHp159612 for ; Wed, 1 Feb 2012 13:13:41 -0700 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q11KDbVg015744 for ; Wed, 1 Feb 2012 13:13:39 -0700 Date: Wed, 1 Feb 2012 12:13:36 -0800 From: "Paul E. McKenney" Subject: Re: [v7 0/8] Reduce cross CPU IPI interference Message-ID: <20120201201336.GI2382@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1327572121-13673-1-git-send-email-gilad@benyossef.com> <1327591185.2446.102.camel@twins> <1328117722.2446.262.camel@twins> <20120201184045.GG2382@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Peter Zijlstra , Gilad Ben-Yossef , linux-kernel@vger.kernel.org, Chris Metcalf , Frederic Weisbecker , linux-mm@kvack.org, Pekka Enberg , Matt Mackall , Sasha Levin , Rik van Riel , Andi Kleen , Mel Gorman , Andrew Morton , Alexander Viro , Avi Kivity , Michal Nazarewicz , Kosaki Motohiro , Milton Miller On Wed, Feb 01, 2012 at 02:06:07PM -0600, Christoph Lameter wrote: > On Wed, 1 Feb 2012, Paul E. McKenney wrote: > > > On Wed, Feb 01, 2012 at 06:35:22PM +0100, Peter Zijlstra wrote: > > > On Sun, 2012-01-29 at 10:25 +0200, Gilad Ben-Yossef wrote: > > > > > > > > If this is of interest, I keep a list tracking global IPI and global > > > > task schedulers sources in the core kernel here: > > > > https://github.com/gby/linux/wiki. > > > > > > You can add synchronize_.*_expedited() to the list, it does its best to > > > bash the entire machine in order to try and make RCU grace periods > > > happen fast. > > > > I have duly added "Make synchronize_sched_expedited() avoid IPIing idle > > CPUs" to http://kernel.org/pub/linux/kernel/people/paulmck/rcutodo.html. > > > > This should not be hard once I have built up some trust in the new > > RCU idle-detection code. It would also automatically apply to > > Frederic's dyntick-idle userspace work. > > Could we also apply the same approach to processors busy doing > computational work? In that case the OS is also not needed. Interrupting > these activities is impacting on performance and latency. Yep, that is in fact what Frederic's dyntick-idle userspace work does. Thanx, Paul -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org