[ntp:questions] Clock jumps when refclock used

A C agcarver+ntp at acarver.net
Sat Apr 28 20:56:36 UTC 2012

Update on the clock jumping.

For the past ten days I left the system running with ATOM and SHM 
noselected to monitor them and used five other network servers for 
general timekeeping.  There were no unusual steps or other behavior that 
I could see.  Additionally, ATOM and SHM behaved normally as far as 
their offsets were concerned.  SHM had offsets that wandered as expected 
(+/-50ms) as it's being fed data from gpsd reading a SiRF GPS receiver. 
  ATOM from the same receiver reasonably matched the overall system 
offset implying that the PPS signal remained stable over those days.

There were a couple instances where remote servers were reported to have 
very large (multi second) offsets on the billboard but they corrected 
themselves and it didn't affect the operation of ntpd.

I've since restarted ntpd and now have it running with ATOM and SHM 
enabled.  SHM is currently configured as the preferred peer.  We'll see 
how this does.

Version is still 4.2.7p270, I haven't had a chance to compile p273 yet.

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