How to diagnose system freezes?

[Julian Elischer]

On 7/31/12 5:02 PM, Yuri wrote:
> One of my 9.1-BETA1 systems periodically freezes. If sound was 
> playing, it would usually cycle with a very short period. And system 
> stops being sensitive to keyboard/mouse. Also ping of this system 
> doesn't get a response.
> I would normally think that this is the faulty memory. But memory 
> was recently replaced and tested with memtest+ for hours both before 
> and after freezes and it passes all tests.
> One out of the ordinary thing that is running on this system is 
> nvidia driver. But the freezes happen even when there is no graphics 
> activity.
> Another out of the ordinary thing is that the kernel is built for 
> DTrace. But DTrace was never used in the sessions that had a freeze.
>
> What is the way to diagnose this problem?
The answer depends on a number of things but an NMI can be useful if 
you have some way of
generating them. (some IPMI implementations can allw you to generate 
them and some motherboards have
jumpers to allow you to attach a 'nmi-button'.

The fact that ping is not responsive is important, as that is done at 
a very low level but
it may still be alive down there somewhere.

Make sure you have debugging enabled in your kernel. That will catch 
quite a few 'hangs'.

as also mentioned by others... a serial console and DDB may also be 
useful in some hangs.


Julian
> CPU: i7 CPU         920  @ 2.67GHz
> Memory: 24GB
> MB: P2T
>
> Yuri
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