From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262089AbVGFT6R (ORCPT ); Wed, 6 Jul 2005 15:58:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262430AbVGFT5c (ORCPT ); Wed, 6 Jul 2005 15:57:32 -0400 Received: from mail.metronet.co.uk ([213.162.97.75]:15786 "EHLO mail.metronet.co.uk") by vger.kernel.org with ESMTP id S262271AbVGFP6z (ORCPT ); Wed, 6 Jul 2005 11:58:55 -0400 From: Alistair John Strachan To: Ingo Molnar Subject: Re: Realtime Preemption, 2.6.12, Beginners Guide? Date: Wed, 6 Jul 2005 16:58:53 +0100 User-Agent: KMail/1.8.1 Cc: linux-kernel@vger.kernel.org References: <200507061257.36738.s0348365@sms.ed.ac.uk> <200507061351.18410.s0348365@sms.ed.ac.uk> <20050706133915.GB19467@elte.hu> In-Reply-To: <20050706133915.GB19467@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200507061658.53845.s0348365@sms.ed.ac.uk> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 06 Jul 2005 14:39, Ingo Molnar wrote: > * Alistair John Strachan wrote: > > Then it continues to boot. I'm getting periodic lockups under high > > network load, however, though I suspect that might be the ipw2200 > > driver I compiled against the realtime-preempt kernel. Are there any > > known issues with external modules versus PREEMPT-RT? > > you should keep an eye on compile-time warnings, but otherwise, most of > the API deviations should be runtime detected and should be reported in > one way or another (if you have all debugging options enabled). I now no longer suspect the ipw2200 module. It locks up within 5 minutes, reliably, with or without network load. I seem to always have to promote a large redraw in X11 before it occurs, but this is just hand waving, I don't really have any evidence. > > > Any way to debug these problems? > > Is it a hard lockup? One good way to debug it is via serial logging and > the NMI watchdog. I've attached a QuickStart below. Another method to > debug hard lockups is to enable 'direct keyboard interrupts', via: > > echo 1 > /proc/sys/kernel/debug_direct_keyboard It's a hard lockup, and I'll attempt to carry this out. > > note that with that switch activated you can use SysRq even when the > system is otherwise locked up, but the keyboard IRQ might crash. So the > best tactic is to not use the keyboard from that point on, only for the > short period of time when you try to get info out of a crashed system, > via SysRq. There's more about this flag in this post: > > http://www.uwsg.iu.edu/hypermail/linux/kernel/0411.2/0936.html > > Ingo As usual Ingo, this is a thorough answer to my query and it explains exactly what I need to do. Fortunately this is an x86 laptop with a serial port, and I can easily find or make a cable to debug it over the serial console. I hope to have some useful information to you by the end of the day. -- Cheers, Alistair. personal: alistair()devzero!co!uk university: s0348365()sms!ed!ac!uk student: CS/CSim Undergraduate contact: 1F2 55 South Clerk Street, Edinburgh. EH8 9PP.