From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758112AbYENXnT (ORCPT ); Wed, 14 May 2008 19:43:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755668AbYENXnI (ORCPT ); Wed, 14 May 2008 19:43:08 -0400 Received: from threatwall.zlynx.org ([199.45.143.218]:37030 "EHLO zlynx.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755394AbYENXnH (ORCPT ); Wed, 14 May 2008 19:43:07 -0400 Subject: Re: troubleshooting/debugging hard locks From: Zan Lynx To: Ray Lee Cc: Lee Howard , linux-kernel@vger.kernel.org In-Reply-To: <2c0942db0805141543n20e6eb6eq5fe13fe1cb50d67e@mail.gmail.com> References: <482B3D21.5020903@howardsilvan.com> <2c0942db0805141543n20e6eb6eq5fe13fe1cb50d67e@mail.gmail.com> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-iW1iRdo2pcqYp8Y3LzXe" Date: Wed, 14 May 2008 17:42:58 -0600 Message-Id: <1210808578.3784.7.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.22.1.1 X-Envelope-From: zlynx@acm.org X-Spam-Id: 20080514/1JwQcd-00048S-VR-linux-kernel@vger.kernel.org:zlynx@acm.org:199.45.143.218 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-iW1iRdo2pcqYp8Y3LzXe Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Wed, 2008-05-14 at 15:43 -0700, Ray Lee wrote: > On Wed, May 14, 2008 at 12:27 PM, Lee Howard wr= ote: > > But, without kernel messages indicating where to look to debug... what= is > > the best approach to start troubleshooting and debugging this condition= ? Is > > there some general debug feature that can be enabled in the kernel that > > would help hone in on the culprit? >=20 > There's something called the NMI watchdog, that will print debugging > messages out if it finds the system has hard locked. The short version > is that you should add "nmi_watchdog=3D1" (no quotes) to the line in > GRUB that has the kernel options. That assumes you have an APIC on the > system. If that's not the case (you're on Uniprocessor, and no APIC) > then you can try nmi_watchdog=3D2 instead. That'll only work on some > systems, though. >=20 > Better docs (than my cheesy writeup) are in > Documentation/nmi_watchdog.txt in the kernel source distribution. I was once told to add these to the kernel command line as well when using NMI watchdog and they do seem to help it trigger more reliably:=20 "idle=3Dpoll nohz=3Doff" --=20 Zan Lynx --=-iW1iRdo2pcqYp8Y3LzXe Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) iEYEABECAAYFAkgreQIACgkQolqWs/Y4NLx/OQCeNJBtCwzzMB8ZummC7fxXYkug UqkAnjgqjenFEJoEDRAXUlXeX1ZBW/Ua =tb5t -----END PGP SIGNATURE----- --=-iW1iRdo2pcqYp8Y3LzXe--