CPU time accounting broken on 8-STABLE machine after a few hours of uptime

[Don Lewis]

On 30 Sep, Andriy Gapon wrote:
> on 30/09/2010 02:27 Don Lewis said the following:

> vmstat -i ?

I didn't see anything odd in the vmstat -i output that I posted to the list
earlier.  It looked more or less normal as the ntp offset suddenly went
insane.
 
>> I did manage to catch the problem with lock profiling enabled:
>> <http://people.freebsd.org/~truckman/AN-M2_HD-8.1-STABLE_lock_profile_freeze.txt>
>> I'm currently testing SMP some more to verify if it really avoids this
>> problem.
> 
> OK.

I wasn't able to cause SMP on stable to break.

The silent reboots that I was seeing with WITNESS go away if I add
WITNESS_SKIPSPIN.  Witness doesn't complain about anything.

I tested -CURRENT and !SMP seems to work ok.  One difference in terms of
hardware between the two tests is that I'm using a SATA drive when
testing -STABLE and a SCSI drive when testing -CURRENT.

At this point, I think the biggest clues are going to be in the lock
profile results.