[ntp:questions] NTP.conf using Dave Hart code.

David Lord snews at lordynet.org
Wed Feb 10 10:26:52 UTC 2010


Dave Hart wrote:
> On Feb 10, 2:39 UTC, David Lord <sn... at lordynet.org> wrote:
>> Target was given above as +/- 10ms so just using
>> "ntpd -q" will get there but here that seems to take
>> between 5-8 minutes. Then after starting ntpd it's
>> about another 4 minutes before ntpd is giving out
>> time. As you say, it takes a few hours to reach
>> offsets in low us. If an ntp server is configured
>> with iburst, the startup time can be even faster.
> 
> ntpd syncs to my GPS+PPS much more quickly than that.  I'm guessing
> you're using a substantially older version of ntpd than 4.2.6 and
> probably also using the default minpoll 6 with your refclock drivers?

Ntpd 4.2.4p6-o is latest I have working.

NMEA type 20 driver doesn't seem to work well with minpoll 4
so is at default minpoll 6. PPS type 22 driver is currently
using minpoll 4.


>> These are from a restart yesterday morning:
>>
>> 09:54:40 clock PPS(0) 'clk_noreply' # ntpd started
>> 09:58:57 synchronized to GPS_NMEA(0), stratum 0
>> 10:00:18 synchronized to PPS(0), stratum 0
> 
> This is not directly comparable because it's from a warm restart of
> ntpd where no step was needed, but in under 20 seconds it was humming:
> 
> 10 Feb 05:05:40 ntpd[5988]: 0.0.0.0 c016 06 restart
> 10 Feb 05:05:40 ntpd[5988]: GPS_NMEA(1) 8024 84 reachable
> 10 Feb 05:05:40 ntpd[5988]: GPS_NMEA(1) 963a 8a sys_peer
> 10 Feb 05:05:40 ntpd[5988]: 0.0.0.0 c415 05 clock_sync
> 10 Feb 05:05:41 ntpd[5988]: PPS(1) 802b 8b clock_event clk_no_reply
> 10 Feb 05:05:57 ntpd[5988]: PPS(1) 8034 84 reachable
> 10 Feb 05:05:57 ntpd[5988]: PPS(1) 974a 8a sys_peer
> 
> The 16s vs. 64s poll intervals only explains part of the difference.
> Another part is newer ntpd jumps on a working PPS signal as soon as it
> is reachable, rather than after 4 polling intervals.

That looks very good and I'd love to see that on my systems.

NetBSD in pkgsrc is only up to ntpd 4.2.4p7 and while
4.2.6p1-RC4 compiles ok and I've managed to actually get
ntpd running, there is no response to queries using ntpq.
Ntpq from 4.2.6p1-RC4 works ok vs ntpd 4.2.4. I'm not a
programmer and even getting patches to apply successfully
is a major task for me so I'll have to stick with 4.2.4p6
until more recent version is ported to NetBSD.

cheers

David




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