From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757632Ab0DRUXu (ORCPT ); Sun, 18 Apr 2010 16:23:50 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:37303 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752266Ab0DRUXs (ORCPT ); Sun, 18 Apr 2010 16:23:48 -0400 Date: Sun, 18 Apr 2010 13:21:13 -0700 (PDT) From: Linus Torvalds To: Mathieu Desnoyers cc: Ingo Molnar , Peter Zijlstra , Mike Galbraith , Andrew Morton , Greg Kroah-Hartman , Steven Rostedt , Jarkko Nikula , Tony Lindgren , linux-kernel@vger.kernel.org Subject: Re: [RFC patch] CFS fix place entity spread issue (v2) In-Reply-To: <20100418131302.GA3614@Krystal> Message-ID: References: <20100418131302.GA3614@Krystal> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 18 Apr 2010, Mathieu Desnoyers wrote: > > CFS fix place entity spread issue (v2) > > Huge CFS vruntime spread (18 minutes) has been observed with LTTng while simply > running Xorg on a uniprocessor machine. Detailed explanation in my ELC2010 > presentation at: Hmm. I tested this patch with my favourite non-scientific desktop load test: do web browsing while doing a kernel compile with "make -j16" (after doing a "git clean -dqfx" and "ccache -C" to get rid of old object files and ccache). This is on a dual-core (with SMT, so 4 threads) Core i5, so "make -j16" overcommits the CPU's quite a bit. And quite frankly, I think your patch makes things much worse. I don't have numbers, but it felt much choppier and slower to do scrolling in firefox o moving windows around while the load average is 20+. My testload is in no way objective, nor necessarily any good, but it's the one I happen to use, and while it's subjective, I think the difference was pretty clear and not good. Linus