From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753019AbZIMGl6 (ORCPT ); Sun, 13 Sep 2009 02:41:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752614AbZIMGl5 (ORCPT ); Sun, 13 Sep 2009 02:41:57 -0400 Received: from mail.gmx.net ([213.165.64.20]:41876 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752563AbZIMGl4 (ORCPT ); Sun, 13 Sep 2009 02:41:56 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1/AWRVqWN3ADYrUCLSeDTsrFEKEDS5ihIRzu/MPJk 7YzLgmdtVqB2ZB Subject: Re: [GIT PULL] sched/core for v2.6.32 From: Mike Galbraith To: Jesper Juhl Cc: Ingo Molnar , Tony Luck , Linus Torvalds , linux-kernel@vger.kernel.org, Peter Zijlstra In-Reply-To: References: <20090911192505.GA20006@elte.hu> <12c511ca0909111924s42d000dsbf378009d9434ddc@mail.gmail.com> <20090912054917.GB9420@elte.hu> Content-Type: text/plain Date: Sun, 13 Sep 2009 08:41:54 +0200 Message-Id: <1252824114.16650.130.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 X-FuHaFi: 0.64 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2009-09-13 at 00:07 +0200, Jesper Juhl wrote: > On Sat, 12 Sep 2009, Ingo Molnar wrote: > > > It was a statistical property based on performance considerations - > > and now we flipped it around based on latency and for kbuild > > performance/throughput reasons: Serge Belyshev reported a 7% > > increase on a quad due to this change and i measured a 1.5% > > peak-kbuild performance increase. > > > Impressive. I wouldn't have expected that much gain by running the parent > first. Actually I personally would have expected child-first to perform > better since (in my experience) it's usually the child that's just forked > that matters the most. How can waiting for child1 to run a bit before forking off child2 _not_ hurt? The parent is the worker bee creator, the queen bee if you will. Seems to me that making the queen wait until one egg hatches and ages a bit before laying another egg is a very bad plan if the goal is to have a hive full of short lived worker bees. -Mike