[time-nuts] PPS jitter - Oncore VP w/NTP

[Warner Losh]

The other issue that you might be fighting is FreeBSD 5's increased
interrupt latency.  I've noticed similar things on the ntp servers
that we produce here, and have traced the problems back to variability
in the ISR running.  Granted this was with a late 5.3 release
candidate, but 5.3 and 5.4 have had simmilar interrupt latency
characteristics in the tests that I've performed.

Warner