From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 19 Mar 2003 03:11:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 19 Mar 2003 03:11:49 -0500 Received: from gateway-1237.mvista.com ([12.44.186.158]:5616 "EHLO av.mvista.com") by vger.kernel.org with ESMTP id ; Wed, 19 Mar 2003 03:11:48 -0500 Message-ID: <3E7828C3.2070304@mvista.com> Date: Wed, 19 Mar 2003 00:22:27 -0800 From: george anzinger User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2) Gecko/20021202 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Andrew Morton CC: async@cc.gatech.edu, linux-kernel@vger.kernel.org Subject: Re: [PATCH] limits on SCHED_FIFO tasks References: <20030318185135.D1361@tokyo.cc.gatech.edu> <3E77C40D.4090700@mvista.com> <20030318190407.37a39db1.akpm@digeo.com> In-Reply-To: <20030318190407.37a39db1.akpm@digeo.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > george anzinger wrote: > >>If the issue is regaining control after some RT task goes into a loop, >>the way this is usually done is to keep a session around with a higher >>priority. Using this concept, one might provide tools that, from >>userland, insure that such a session exists prior to launching the >>"suspect" code. I fail to see the need for this sort of code in the >>kernel. > > > That works, until your shell calls ext3_mark_inode_dirty(), which blocks on > kjournald activity. kjournald is SCHED_OTHER, and never runs... > That is classic priority inversion. It would be "nice" to find a fix for that :) I think that the proposed action should not be triggered until there is some "notice" that something is wrong. I suppose it could be a watchdog timer of some sort. Still, if the priority inversion issue were solved, all the rest could be done in user land. > > -- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml