From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031134AbXDSFRR (ORCPT ); Thu, 19 Apr 2007 01:17:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1031154AbXDSFRR (ORCPT ); Thu, 19 Apr 2007 01:17:17 -0400 Received: from smtp1.osdl.org ([65.172.181.25]:57223 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031134AbXDSFRQ (ORCPT ); Thu, 19 Apr 2007 01:17:16 -0400 Date: Wed, 18 Apr 2007 22:14:32 -0700 From: Andrew Morton To: Nick Piggin Cc: Linus Torvalds , Matt Mackall , William Lee Irwin III , Peter Williams , Mike Galbraith , Con Kolivas , Ingo Molnar , ck list , Bill Huey , linux-kernel@vger.kernel.org, Arjan van de Ven , Thomas Gleixner Subject: Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS] Message-Id: <20070418221432.e4dbcf4f.akpm@linux-foundation.org> In-Reply-To: <20070419031807.GA24512@wotan.suse.de> References: <20070417060955.GO8915@holomorphy.com> <20070417061503.GC1057@wotan.suse.de> <20070417062621.GL2986@holomorphy.com> <20070417070155.GF1057@wotan.suse.de> <20070417213954.GE11166@waste.org> <20070418031511.GA18452@wotan.suse.de> <20070418043831.GR11115@waste.org> <20070418050024.GF18452@wotan.suse.de> <20070418055525.GS11115@waste.org> <20070419031807.GA24512@wotan.suse.de> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 19 Apr 2007 05:18:07 +0200 Nick Piggin wrote: > And yes, by fairly, I mean fairly among all threads as a base resource > class, because that's what Linux has always done Yes, there are potential compatibility problems. Example: a machine with 100 busy httpd processes and suddenly a big gzip starts up from console or cron. Under current kernels, that gzip will take ages and the httpds will take a 1% slowdown, which may well be exactly the behaviour which is desired. If we were to schedule by UID then the gzip suddenly gets 50% of the CPU and those httpd's all take a 50% hit, which could be quite serious. That's simple to fix via nicing, but people have to know to do that, and there will be a transition period where some disruption is possible.