Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932293Ab3CGJnu (ORCPT ); Thu, 7 Mar 2013 04:43:50 -0500 Received: from mout.gmx.net ([212.227.17.22]:50710 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755107Ab3CGJnr (ORCPT ); Thu, 7 Mar 2013 04:43:47 -0500 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1/lI+cEJHLlfzkwdN2MD7+xHTwnQwXfnfwgC9QGTb Ar/itjc14FrqIq Message-ID: <1362649419.4652.12.camel@marge.simpson.net> Subject: Re: [PATCH] sched: wakeup buddy From: Mike Galbraith To: Peter Zijlstra Cc: Michael Wang , LKML , Ingo Molnar , Namhyung Kim , Alex Shi , Paul Turner , Andrew Morton , "Nikunj A. Dadhania" , Ram Pai Date: Thu, 07 Mar 2013 10:43:39 +0100 In-Reply-To: <1362645372.2606.11.camel@laptop> References: <5136EB06.2050905@linux.vnet.ibm.com> <1362645372.2606.11.camel@laptop> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1186 Lines: 28 On Thu, 2013-03-07 at 09:36 +0100, Peter Zijlstra wrote: > On Wed, 2013-03-06 at 15:06 +0800, Michael Wang wrote: > > > wake_affine() stuff is trying to bind related tasks closely, but it doesn't > > work well according to the test on 'perf bench sched pipe' (thanks to Peter). > > so sched-pipe is a poor benchmark for this.. > > Ideally we'd write a new benchmark that has some actual data footprint > and we'd measure the cost of tasks being apart on the various cache > metrics and see what affine wakeup does for it. > > Before doing something like what you're proposing, I'd have a hard look > at WF_SYNC, it is possible we should disable/fix select_idle_sibling > for sync wakeups. If nobody beats me to it, I'm going to try tracking shortest round trip to idle, and use a multiple of that to shut select_idle_sibling() down. If avg_idle approaches round trip time, there's no win to be had, we're just wasting cycles. -Mike -- 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/