From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754599Ab2C0N4o (ORCPT ); Tue, 27 Mar 2012 09:56:44 -0400 Received: from mailout-de.gmx.net ([213.165.64.22]:46659 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754276Ab2C0N4m (ORCPT ); Tue, 27 Mar 2012 09:56:42 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX19j77Eq14tjl2X+tMk6vlr1pVrS7i4C1c0nWi2OXZ 8CTulo9UR760Qr Message-ID: <1332856598.7425.25.camel@marge.simpson.net> Subject: Re: sched: Avoid SMT siblings in select_idle_sibling() if possible From: Mike Galbraith To: Peter Zijlstra Cc: Srivatsa Vaddagiri , Ingo Molnar , Suresh Siddha , linux-kernel , Paul Turner Date: Tue, 27 Mar 2012 15:56:38 +0200 In-Reply-To: <1332785212.16159.170.camel@twins> References: <1329764866.2293.376.camhel@twins> <20120305152443.GE26559@linux.vnet.ibm.com> <20120306091410.GD27238@elte.hu> <20120322153205.GA28570@linux.vnet.ibm.com> <1332750960.16159.81.camel@twins> <20120326173533.GA4689@linux.vnet.ibm.com> <1332785212.16159.170.camel@twins> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.1 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 On Mon, 2012-03-26 at 20:06 +0200, Peter Zijlstra wrote: > The biggest regression came from tbench, wasn't that mostly a random > number generator anyway? That's dbench ;-) Tbench does wiggle around more than you'd like though. I've never tracked, but in lots of running the thing, 2-3% you can forget chasing, and I once bisected a 5% regression to an unrelated change, reverted and re-applied the suspect a few times in disbelief, and it tracked. You can't trust it _too_ much. I consider it a reliable indicator that I'd better do more testing. If others agree, it's a real regression, if not, it's those damn Elves 'n Gremlins ;-) -Mike