From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964847AbWFSSzd (ORCPT ); Mon, 19 Jun 2006 14:55:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964841AbWFSSzc (ORCPT ); Mon, 19 Jun 2006 14:55:32 -0400 Received: from zcars04e.nortel.com ([47.129.242.56]:14578 "EHLO zcars04e.nortel.com") by vger.kernel.org with ESMTP id S964847AbWFSSzb (ORCPT ); Mon, 19 Jun 2006 14:55:31 -0400 Message-ID: <4496F310.9010807@nortel.com> Date: Mon, 19 Jun 2006 12:55:12 -0600 From: "Chris Friesen" User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.7) Gecko/20050427 Red Hat/1.7.7-1.1.3.4 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Peter Williams CC: Andrew Morton , Kirill Korotaev , Srivatsa , CKRM , Linux Kernel , Balbir Singh , Mike Galbraith , Sam Vilain , Con Kolivas , Kingsley Cheung , Ingo Molnar , Rene Herman Subject: Re: [ckrm-tech] [PATCH 0/4] sched: Add CPU rate caps References: <20060618082638.6061.20172.sendpatchset@heathwren.pw.nest> In-Reply-To: <20060618082638.6061.20172.sendpatchset@heathwren.pw.nest> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 19 Jun 2006 18:55:17.0179 (UTC) FILETIME=[E7B9A8B0:01C693D1] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Peter Williams wrote: > These patches implement CPU usage rate limits for tasks. Personally, I'm more comfortable with guarantees rather than limits. Specifying a limit doesn't do anything to ensure that a task (or group of tasks) gets enough cpu time to actually accomplish anything unless you specify limits on every task in the system. Suppose you have a server app that needs at least 50% of the cpu. With a guarantee, you can say "this guy needs 50%, and I don't care about anything else". With limits you have to flip it around--"all these guys together are limited to 50%, and that guy isn't limited". Seems counterintuitive. Chris