From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031154AbXDSGik (ORCPT ); Thu, 19 Apr 2007 02:38:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1031161AbXDSGik (ORCPT ); Thu, 19 Apr 2007 02:38:40 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:56119 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031154AbXDSGij (ORCPT ); Thu, 19 Apr 2007 02:38:39 -0400 Date: Thu, 19 Apr 2007 08:38:10 +0200 From: Ingo Molnar To: Andrew Morton Cc: Nick Piggin , Linus Torvalds , Matt Mackall , William Lee Irwin III , Peter Williams , Mike Galbraith , Con Kolivas , 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: <20070419063810.GA22418@elte.hu> References: <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> <20070418221432.e4dbcf4f.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070418221432.e4dbcf4f.akpm@linux-foundation.org> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Andrew Morton 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. hmmmm. How about the following then: default to nice -10 for all (SCHED_NORMAL) kernel threads and all root-owned tasks. Root _is_ special: root already has disk space reserved to it, root has special memory allocation allowances, etc. I dont see a reason why we couldnt by default make all root tasks have nice -10. This would be instantly loved by sysadmins i suspect ;-) (distros that go the extra mile of making Xorg run under non-root could also go another extra one foot to renice that X server to -10.) Ingo