Re: Hang and Soft Lockup problems with generic time code

[James Bottomley]

On Sat, 2006-07-08 at 14:47 -0700, john stultz wrote:
> > Well, what I was seeing was that 
> > 
> > clocksource_read(clock) - clock->cycle_last
> > 
> > is returning a value about 200 x clock->cycle_interval
> 
> That then would be ~200 ticks. Is this at HZ=1000 ? 

no, 250.

> > According to the debugging printks I put into update_wall_time().  I was
> > assuming this was caused by a jump in the TSC count, but I suppose it
> > could also be cause by spurious alterations to cycle_last or other
> > effects I haven't traced.
> 
> Since this issue effected both the TSC and ACPI PM timer, I'd more
> likely suspect something is holding off the timer interrupt. This could
> be some kernel code like a driver, or it could be something like an SMI
> from the BIOS.

The driver takes only ~10s to insert and these cycle jumps occur within
that time frame, so it's not a real 200s.  The timer system has somehow
manufactured the cycle jump.

James


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