Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [patch] x86_64: do not enable the NMI watchdog by default | Date | Thu, 7 Dec 2006 18:24:33 +0100 |
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> and it needs to be > undone via the patch attached further below.
I disagree. And it has often saved my ass on 64bit. I
On 32bit it might be reevaluated -- i didn't expect that amount of laptop firmware bugs triggered by it, but I'm not quite ready to give up on that yet.
> If Andi wants to debug stuff via the NMI wachdog, he should use the > nmi_watchdog=2 boot option:
This means for most lockups which are hard to reproduce we don't get any backtrace.
And nmi_watchdog=2 is bad because it runs at HZ frequency and has quite high overhead.
> also, lock debugging facilities catch lockup possibilities (and actual > lockups) alot more efficiently,
Production kernels don't have lock debugging enabled because it has far too much overhead.
> 8 were caught by lockdep, 8 by atomicity checks in the scheduler, 7 by > DEBUG_PREEMPT and 1 by DEBUG_SPINLOCK.
None of which is enabled on non debug kernels.
> Note: zero were caught by the NMI watchdog, and i run the NMI watchdog > enabled by default on all architectures, and i have serial logging of > everything.
Sure lock debugging will probably catch most of this earlier, but we don't have it usually.
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