Re: frequent lockups in 3.18rc4

From: Dave Jones
Date: Wed Dec 03 2014 - 15:45:33 EST


On Wed, Dec 03, 2014 at 09:37:10PM +0100, Thomas Gleixner wrote:

> Right, that resulted in a delta > 0. I have no idea how we could
> create a negative delta via wrapping the HPET around, i.e. HPET being
> 96 seconds ahead of TSC.
>
> This looks more like a genuine TSC wreckage. So we have these possible
> causes:
>
> 1) SMI
>
> 2) Power states
>
> 3) Writing to the wrong MSR
>
> So I assume that 1/2 are a non issue. They should surface in normal
> non fuzzed operation as well.
>
> Dave, does that TSC unstable thing always happen AFTER you started
> fuzzing? If yes, what is the fuzzer doing this time?

I've seen it even after doing just a kernel build sometimes, It's
happened so regularly I've just assumed "the tsc is crap on this box".

On occasion I even see it shortly after boot, while idle.

Dave

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