From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265016AbTGGPMZ (ORCPT ); Mon, 7 Jul 2003 11:12:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266661AbTGGPMZ (ORCPT ); Mon, 7 Jul 2003 11:12:25 -0400 Received: from mail-in-04.arcor-online.net ([151.189.21.44]:4044 "EHLO mail-in-04.arcor-online.net") by vger.kernel.org with ESMTP id S265016AbTGGPMY (ORCPT ); Mon, 7 Jul 2003 11:12:24 -0400 From: Daniel Phillips To: Davide Libenzi , Mel Gorman Subject: Re: 2.5.74-mm1 Date: Mon, 7 Jul 2003 17:28:08 +0200 User-Agent: KMail/1.5.2 Cc: Jamie Lokier , Andrew Morton , Linux Kernel Mailing List , Linux Memory Management List References: <20030703023714.55d13934.akpm@osdl.org> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200307071728.08753.phillips@arcor.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Monday 07 July 2003 16:47, Davide Libenzi wrote: > On Mon, 7 Jul 2003, Mel Gorman wrote: > > On Mon, 7 Jul 2003, Daniel Phillips wrote: > > > And set up distros to grant it by default. Yes. > > > > > > The problem I see is that it lets user space priorities invade the > > > range of priorities used by root processes. > > > > That is the main drawback all right but it could be addressed by having a > > CAP_SYS_USERNICE capability which allows a user to renice only their own > > processes to a highest priority of -5, or some other reasonable value > > that wouldn't interfere with root processes. This capability would only > > be for applications like music players which need to give hints to the > > scheduler. > > The scheduler has to work w/out external input, period. If it doesn't we > have to fix it and not to force the user to submit external hints. That's not correct in this case, because the sound servicing routine is realtime, which makes it special. Furthermore, Zinf is already trying to provide the kernel with the hint it needs via PThreads SetPriority but because Linux has brain damage - both in the kernel and user space imho - the hint isn't accomplishing what it's supposed to. As I said earlier: trying to detect automagically which threads are realtime and which aren't is stupid. Such policy decisions don't belong in the kernel. Regards, Daniel