From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2993161AbXDSH6T (ORCPT ); Thu, 19 Apr 2007 03:58:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2993162AbXDSH6S (ORCPT ); Thu, 19 Apr 2007 03:58:18 -0400 Received: from holomorphy.com ([66.93.40.71]:41149 "EHLO holomorphy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2993161AbXDSH6S (ORCPT ); Thu, 19 Apr 2007 03:58:18 -0400 Date: Thu, 19 Apr 2007 00:57:46 -0700 From: William Lee Irwin III To: Ingo Molnar Cc: Andrew Morton , Nick Piggin , Linus Torvalds , Matt Mackall , 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: <20070419075746.GD31925@holomorphy.com> References: <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> <20070419063810.GA22418@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070419063810.GA22418@elte.hu> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Andrew Morton wrote: >> 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. [...] On Thu, Apr 19, 2007 at 08:38:10AM +0200, Ingo Molnar wrote: > 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.) I'd further recommend making priority levels accessible to kernel threads that are not otherwise accessible to processes, both above and below user-available priority levels. Basically, if you can get SCHED_RR and SCHED_FIFO to coexist as "intimate scheduler classes," then a SCHED_KERN scheduler class can coexist with SCHED_OTHER in like fashion, but with availability of higher and lower priorities than any userspace process is allowed, and potentially some differing scheduling semantics. In such a manner nonessential background processing intended not to ever disturb userspace can be given priorities appropriate to it (perhaps even con's SCHED_IDLEPRIO would make sense), and other, urgent processing can be given priority over userspace altogether. I believe root's default priority can be adjusted in userspace as things now stand somewhere in /etc/ but I'm not sure of the specifics. Word is somewhere in /etc/security/limits.conf -- wli