From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751942AbcEAJU3 (ORCPT ); Sun, 1 May 2016 05:20:29 -0400 Received: from mx2.suse.de ([195.135.220.15]:43352 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750992AbcEAJU2 (ORCPT ); Sun, 1 May 2016 05:20:28 -0400 Message-ID: <1462094425.9717.45.camel@suse.de> Subject: Re: sched: tweak select_idle_sibling to look for idle threads From: Mike Galbraith To: Peter Zijlstra Cc: Chris Mason , Ingo Molnar , Matt Fleming , linux-kernel@vger.kernel.org Date: Sun, 01 May 2016 11:20:25 +0200 In-Reply-To: <20160501085303.GF2975@worktop.cust.blueprintrf.com> References: <20160405180822.tjtyyc3qh4leflfj@floor.thefacebook.com> <20160409190554.honue3gtian2p6vr@floor.thefacebook.com> <20160430124731.GE2975@worktop.cust.blueprintrf.com> <1462086753.9717.29.camel@suse.de> <20160501085303.GF2975@worktop.cust.blueprintrf.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2016-05-01 at 10:53 +0200, Peter Zijlstra wrote: > On Sun, May 01, 2016 at 09:12:33AM +0200, Mike Galbraith wrote: > > On Sat, 2016-04-30 at 14:47 +0200, Peter Zijlstra wrote: > > > > Can you guys have a play with this; I think one and two node tbench are > > > good, but I seem to be getting significant run to run variance on that, > > > so maybe I'm not doing it right. > > > > Nah, tbench is just variance prone. It got dinged up at clients=cores > > on my desktop box, on 4 sockets the high end got seriously dinged up. > > Ouch, yeah, big hurt. Lets try that again... :-) Yeah, box could use a little bandaid and a hug :) Playing with Chris' benchmark, seems the biggest problem is that we don't buddy up waker of many and it's wakees in a node.. ie the wake wide thing isn't necessarily our friend when there are multiple wakers of many. If I run an instance per node with one mother of all work in autobench mode, it works exactly as you'd expect, game over is when wakees = socket size. It never get's near that point if I let things wander, it beats itself up well before we get there. -Mike