From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030363AbXCSQhi (ORCPT ); Mon, 19 Mar 2007 12:37:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030368AbXCSQhi (ORCPT ); Mon, 19 Mar 2007 12:37:38 -0400 Received: from il.qumranet.com ([82.166.9.18]:60163 "EHLO il.qumranet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030363AbXCSQhi (ORCPT ); Mon, 19 Mar 2007 12:37:38 -0400 Message-ID: <45FEBC51.6060707@argo.co.il> Date: Mon, 19 Mar 2007 18:37:37 +0200 From: Avi Kivity User-Agent: Thunderbird 1.5.0.10 (X11/20070302) MIME-Version: 1.0 To: Helge Hafting CC: davids@webmaster.com, "Linux-Kernel@Vger. Kernel. Org" Subject: Re: is RSDL an "unfair" scheduler too? References: <45FEAB60.7090704@argo.co.il> <45FEB50E.2040104@aitel.hist.no> In-Reply-To: <45FEB50E.2040104@aitel.hist.no> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Helge Hafting wrote: > Avi Kivity wrote: >> >> A fairly contrived example, but I see your point. Of course any >> system can be broken. I think that user-level scheduling is good for >> real multi user systems, where 'user' means a person, not an >> artificial entity. It's also good for a multi application server, >> where typically each service runs (or can be made to run) as a >> separate user. > For a not so contrived example, look at email delivery. Some > mailservers do > all work as root (or some fixed email user) > > Some servers will switch to the UID of the user receiving the message, > limiting the > damage in case of buffer overflow etc. A fair amount of work is then done > as that user - running the message through virus/spam-checks and > then perhaps procmail. > Actually that makes some sense with user level scheduling - delivering email is charged to the recipient instead of to the system. But I agree it's a surprising side effect and if this is ever implemented it should be optional. -- error compiling committee.c: too many arguments to function