[ntp:questions] Panic stop captured

Brian Utterback brian.utterback at oracle.com
Sat Dec 15 01:49:18 UTC 2012

On 12/14/12 16:11, A C wrote:
> I finally had a panic stop with an instrumented copy of 4.2.7p270 
> which was capturing various values inside the functions 
> refclock_process_f and  refclock_process_offset.
> I'm going to post an entire capture of the log but one thing I noticed 
> is that the value of pp->nsec at the top of refclock_process_f slowly 
> ticks down and then wraps around.  Eventually a panic stop happens:
> panic_stop +2147483648 s; set clock manually within 1000 s.
> (but the clock hasn't changed, the system time is still correct to 
> within a second of all my other systems).
> Apparently the wrap around happens pretty frequently so it's not 
> likely the cause of the problem.
> For now the log is available at http://acarver.net/ntpd/ntpd_panic.log 
> (8 MB file, be warned) in case any of you has an idea about what might 
> be happening to cause the panic or there's anything else I should 
> instrument and write to the logs instead.  There are several steps in 
> each of the functions written out to the log looking for overflows or 
> similar.  I do have various statistics files for that period, too, if 
> they would be useful.
> _______________________________________________
> questions mailing list
> questions at lists.ntp.org
> http://lists.ntp.org/listinfo/questions

Not know where how the executable was instrumented, it is hard to tell 
exactly what all of this output means. But there is one thing that jumps 
out at me. Exactly at the time that the panic stop occurs, ntpd has just 
peered with the SHM refclock. This suggests that the time stored in 
shared memory is either uninitialized or is the wrong format.


Always code as if the guy who ends up maintaining your code will be a
violent psychopath who knows where you live. - Martin Golding
Brian Utterback - Solaris RPE, Oracle Corporation.
Ph:603-262-3916, Em:brian.utterback at oracle.com

More information about the questions mailing list