Re: NTP with only GPS/PPS flags PPS as falseticker

[Gary E. Miller]

Yo Nick!

On Thu, 19 Mar 2020 01:57:34 +0000
"Nick Burkitt" <address@hidden> wrote:

> >But, I thought you were using gpsd, thus the NTPsec SHM driver is
> >what you want.  
> I'm in the grasping-at-straws stage at the moment. At least, I'm
> willing to try stuff to see if it helps.

And yet, not trying the things people suggest.  Like chronyd, etc.

> >"Thinking" (guessing) is not good.  Easy to know:
> >
> >      # ppstest /dev/pps0  
> This works fine. We're revisiting old territory here...

Then you should have said "know", not "Thinking".  We many drive-by's
here, and people changing things without saying anything.  So
always good to restate your current configuration.


> root@MPM-4006:~# ppstest /dev/pps0
> trying PPS source "/dev/pps0"
> found PPS source "/dev/pps0"
> ok, found 1 source(s), now start fetching data...
> source 0 - assert 1584581522.999957214, sequence: 977 - clear 
> 0.000000000, sequence: 0

Thar sure looks like your gpsd/ntpd is working.  Less than 50 micro
second offset.  Only PPS (or PTP) give you that.

> I've gone through the exercise of capturing the falling edge, too. It 
> doesn't help.

Yes, as previously discussed.  But the result above is VERY different
from your previous reports.

> >I'll have to ask, yet again:
> >
> >     have you tried to set minsane?  
> Yes, here's my ntp.conf. We've been here before, too.
> 
> minsane 1

No.  You never showed that.  Good thing you did, as that is wrong.
That should be throwing errors in the logs you have not shown us.

The correct line is::

tos minsane 1

> server 0.us.pool.ntp.org iburst
> server 1.us.pool.ntp.org iburst
> server 2.us.pool.ntp.org iburst
> server 3.us.pool.ntp.org iburst

And I've complained about the iburst before.  As well as using the pool.

> >     whnat do you ntpd logs show?  
> ntpd.log shows this after restarting with -D 10 (using "tail -1000 
> /var/log/ntpd.log | grep -a -v DNS", since no network connection)

Gack.  The interesting part is at the top, not the tail!!

So, once again, what do your ntpd logs show??

> Are there other logs I should look at?

Let us start with ntpd.log.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

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    "If you can't measure it, you can't improve it." - Lord Kelvin

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