Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753632AbZIIR56 (ORCPT ); Wed, 9 Sep 2009 13:57:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753427AbZIIR55 (ORCPT ); Wed, 9 Sep 2009 13:57:57 -0400 Received: from thunk.org ([69.25.196.29]:58544 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752682AbZIIR55 (ORCPT ); Wed, 9 Sep 2009 13:57:57 -0400 Date: Wed, 9 Sep 2009 13:57:24 -0400 From: Theodore Tso To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, efault@gmx.de, tglx@linutronix.de, mingo@elte.hu Cc: linux-tip-commits@vger.kernel.org Subject: Re: [tip:sched/core] sched: Turn off child_runs_first Message-ID: <20090909175724.GY22901@mit.edu> Mail-Followup-To: Theodore Tso , mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, efault@gmx.de, tglx@linutronix.de, mingo@elte.hu, linux-tip-commits@vger.kernel.org References: <1252486344.28645.18.camel@marge.simson.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@mit.edu X-SA-Exim-Scanned: No (on thunker.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1073 Lines: 26 On Wed, Sep 09, 2009 at 03:37:07PM +0000, tip-bot for Mike Galbraith wrote: > Commit-ID: 2bba22c50b06abe9fd0d23933b1e64d35b419262 > Gitweb: http://git.kernel.org/tip/2bba22c50b06abe9fd0d23933b1e64d35b419262 > Author: Mike Galbraith > AuthorDate: Wed, 9 Sep 2009 15:41:37 +0200 > Committer: Ingo Molnar > CommitDate: Wed, 9 Sep 2009 17:30:05 +0200 > > sched: Turn off child_runs_first > > Set child_runs_first default to off. > > It hurts 'optimal' make -j workloads as make jobs > get preempted by child tasks, reducing parallelism. Wasn't one of the reasons why we historically did child_runs_first was so that for fork/exit workloads, the child has a chance to exec the new process? If the parent runs first, then more pages will probably need to be COW'ed. - Ted -- 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/