Re: [chrony-users] GPS / Chrony NTP server config questions

[Miroslav Lichvar <mlichvar@xxxxxxxxxx>]

On Tue, Nov 14, 2017 at 03:45:41PM -0500, Joe Smith wrote:
> I rebuilt chrony with --enable-debug and ran with -d -d  Below is some
> output although I'm not 100% sure what it means. Tried looking at the
> source code to see if I could ascertain the cause but I was unable. I let
> it run for a bit and here's some sample output. The pattern just seems to
> repeat over and over.

The "sync=0 dist=1.5" part says the system clock is not synchronized,
which suggests it's not trying to lock to the NMEA source. Looking at
your config again, I see now that the PPS refclock is missing "lock
NMEA".

Alternatively, you could try to remove noselect from the NMEA line, so
chronyd can synchronize the clock to the NMEA source first and then
it can switch to PPS.

> 2017-11-14T20:34:22Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse
> ignored offset=0.003559951 sync=0 dist=1.500000000
> 2017-11-14T20:34:23Z refclock_shm.c:104:(shm_poll) SHM sample ignored
> mode=1 count=1202324 valid=0
> 2017-11-14T20:34:23Z sources.c:356:(SRC_AccumulateSample) ip=[NMEA]
> t=1510691656.723338336 ofs=0.080481 del=0.200000 disp=0.009623 str=0
> 2017-11-14T20:34:23Z sourcestats.c:583:(SST_DoNewRegression)
> off=1.007180e-01 freq=6.636850e-05 skew=3.159318e-04 n=16 bs=0 runs=10
> asym=0.000000 arun=0
> 
> On Tue, Nov 14, 2017 at 10:36 AM, Miroslav Lichvar <mlichvar@xxxxxxxxxx>
> wrote:
> 
> > On Tue, Nov 14, 2017 at 07:40:33AM -0500, Joe Smith wrote:
> > > Thank you for the quick response Bill... The PPS is coming in on
> > /dev/pps1
> > > which is what I have in the refclock entry in my chrony.conf file. When
> > run
> > > the cat command corresponding to that device I get:
> > >
> > > debian@beaglebone:~/ntp-gps-server/pps-overlay$ cat
> > > /sys/devices/virtual/pps/pps1/assert
> > > 1510661769.997836084#571264
> >
> > That looks good. The configuration also looks good. I guess the only
> > thing that could be wrong is the offset value on the SHM line. Does
> > the machine have an internet connection? It might help if you could
> > configure it with an NTP server and remove the lock option from PPS to
> > see if it works that way and to see if the offset of the NMEA source
> > needs to be adjusted.
> >
> > If that doesn't work, recompiling chrony with debug support
> > (--enable-debug) and running chronyd with -d -d should show why it's
> > ignoring the PPS samples.
> >
> > --
> > Miroslav Lichvar
> >
> > --
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> >
> >

-- 
Miroslav Lichvar

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