Messages in this thread | | | Subject | Re: troubleshooting/debugging hard locks | From | Zan Lynx <> | Date | Wed, 14 May 2008 17:42:58 -0600 |
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On Wed, 2008-05-14 at 15:43 -0700, Ray Lee wrote: > On Wed, May 14, 2008 at 12:27 PM, Lee Howard <faxguy@howardsilvan.com> wrote:
> > 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? > > 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=1" (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=2 instead. That'll only work on some > systems, though. > > 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:
"idle=poll nohz=off"
-- Zan Lynx <zlynx@acm.org> [unhandled content-type:application/pgp-signature] | |