[ntp:questions] ATOM falseticker with flag3 enabled

David Lord snews at lordynet.org
Fri Mar 30 10:30:30 UTC 2012

A C wrote:
> On 3/29/2012 03:29, David Lord wrote:
>> Dave Hart wrote:
>>> On Thu, Mar 29, 2012 at 02:44, A C <agcarver+ntp at acarver.net> wrote:
>>>> Without flag3 it appears that ntpd does the heavy lifting but is
>>>> unable to
>>>> use the PPS unless a prefer peer is set. With flag3 enabled, PPS is
>>>> running
>>>> without a prefer peer.
>>> Being unable to use the PPS unless either a prefer peer is set or
>>> another knob is adjusted (see what I quoted earlier) is operating by
>>> design. The change in operation with flag3 1 seems likely to me to be
>>> an ntpd bug, which is why I'd like to see a bug report filed. Unless
>>> I'm missing some design intention, it seems to me PPS should not
>>> become reachable with no prefer peer regardless of flag3.
>> On NetBSD-5, i386, I had the PPS marked as falseticker as
>> from March 2, 2012 when I updated from 4.2.6p3 to 4.2.6p5.
>> When I went back to 4.2.6p3 the 'o' was back. I hadn't spare
>> time to investigate and changed config to use only type 20
>> nmea driver with 4.2.6p5.
> Interesting, so that's the same OS on two platforms with similar 
> problems.  Did you happen to also observe your minimum jitter times in 
> the upgrade?  When I run 4.2.6 my minimum jitter is reported as 0.061ms. 
>  But in 4.2.7 the minimum jitter is 0.122ms, exactly double the 4.2.6 
> value.
> I'm still tinkering with my configuration to see if I can get ATOM to 
> stop being a false ticker but no luck yet even though it's still 
> disciplining the clock.

Jitter depends on time of day, weather etc. The variations
doesn't seem to have been altered by the update from 4.2.6p3
to p5.

I didn't tinker as something is obviously broken with
type 22 driver in p5.


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