Miroslav,
See the most recent ntp-dev. It needed some tuning.
Dave
Miroslav Lichvar wrote:
On Mon, Oct 25, 2010 at 05:31:57PM +0000, David L. Mills wrote:
For record, a hold timer is started when the first update is
received after startup and ends when the residual offset is less
than 0.5 ms or after a timeout of 600 s. During the hold interval
the PLL loop time constant is set very low and the frequency
discipline is disabled. With this arrangement, the offset typical
converges within 600 s, even with initial offsets up to +-100 ms,
and much less if the initial offset is in the 10-50 ms range. If you
see different behavior, either with client/server or broadcast
modes, please report.
I think I see a different behavior. I did few runs and made
offset/time plots. This is with client/server mode, 1ppb/s random walk
frequency noise, zero initial frequency offset, 100ms initial time
offset, 100us jitter (exponential distribution) and no drift file.
http://mlichvar.fedorapeople.org/tmp/ntp_start1.png
http://mlichvar.fedorapeople.org/tmp/ntp_start2.png
http://mlichvar.fedorapeople.org/tmp/ntp_start3.png
The first two are with daemon loop and the third one is with kernel
loop (SHIFT_PLL=4). A negative initial offset doesn't change the
outcome. The first one is particularly bad, looks like it went over
the step limit few times.
1 Jan 01:00:00 ntpd.new[6319]: ntpd [email protected] Mon Oct 25 09:43:53 UTC
2010 (1)
1 Jan 01:00:00 ntpd.new[6319]: proto: precision = 0.101 usec
1 Jan 01:00:00 ntpd.new[6319]: ntp_io: estimated max descriptors: 1024, initial
socket boundary: 16
1 Jan 01:00:00 ntpd.new[6319]: Listen and drop on 0 v4wildcard 0.0.0.0 UDP 123
1 Jan 01:00:00 ntpd.new[6319]: Listen normally on 1 lo 127.0.0.1 UDP 123
1 Jan 01:00:00 ntpd.new[6319]: Listen normally on 2 eth0 192.168.123.3 UDP 123
1 Jan 01:00:00 ntpd.new[6319]: 192.168.123.1 8011 81 mobilize assoc 9201
1 Jan 01:00:00 ntpd.new[6319]: 0.0.0.0 c016 06 restart
1 Jan 01:00:00 ntpd.new[6319]: 0.0.0.0 c012 02 freq_set kernel 0.000 PPM
1 Jan 01:00:00 ntpd.new[6319]: 0.0.0.0 c011 01 freq_not_set
1 Jan 01:00:01 ntpd.new[6319]: 192.168.123.1 8024 84 reachable
1 Jan 01:03:17 ntpd.new[6319]: 192.168.123.1 963a 8a sys_peer
1 Jan 01:03:17 ntpd.new[6319]: 0.0.0.0 c614 04 freq_mode
1 Jan 01:08:41 ntpd.new[6319]: 0.0.0.0 0612 02 freq_set kernel -96.799 PPM
1 Jan 01:08:41 ntpd.new[6319]: 0.0.0.0 0615 05 clock_sync
Looks like the frequency calibration doesn't work correctly here.
Please let me know if you need more information.
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