ntpd loose 10s

[Emmanuel Dreyfus <manu%netbsd.org@localhost>]

Hi

From time to time, nagios raise me an alert for a xen DOMU 
(NetBSD 6.0/i386, Xen 4.1.3) because time suddently shifted of 10s.

ntpd still considers itself in sync (see status below). And the
problem resolves itself as it appeared. Anyone has an idea of what 
can be going on?

# cat /etc/ntp.conf                                                            
pidfile         /var/run/ntpd.pid
driftfile       /var/db/ntp.drift
logconfig       -syncstatus
server          ntp.example.net

# ntpdc 
ntpdc> kerninfo
pll offset:           -0.00603435 s
pll frequency:        -103.546 ppm
maximum error:        3.79263 s
estimated error:      0.0141 s
status:               6001  pll nano mode=fll
pll time constant:    10
precision:            1e-09 s
frequency tolerance:  496 ppm

# date; rdate -p ntp.example.net
Thu Jan 10 10:10:17 CET 2013
Thu Jan 10 10:10:05 2013


-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost