[ntp:questions] Performance?

dhavey dhavey at gmail.com
Mon Dec 22 22:15:16 UTC 2008


On Dec 22, 1:52 pm, dhavey <dha... at gmail.com> wrote:
> On Dec 22, 1:25 pm, Unruh <unruh-s... at physics.ubc.ca> wrote:
>
>
>
> > It is because you are using the nmea from them, not the PPS input and NMEA
> > takes a few msec to go from the GPS to your computer ( 60 characters at
> > 9600BD ).
>
> > dhavey <dha... at gmail.com> writes:
> > >This is the ntpq -p output from 2 machines connected to Garmin GPS's.
> > >The machines ip's of the 2 machines are 192.168.0.28 and .29.  They
> > >are about a millisecond apart!  That's no better than the server
> > >without the GPS.  What did I do to deserve such lousy performance.?
> > >server 127.127.20.0 prefer minpoll 4
> > >fudge 127.127.20.0 refid GPS flag3 1 flag2 0 time1 0.0
> > > and the machines are peered together.
> > >     remote           refid      st t when poll reach   delay
> > >offset  jitter
> > >==============================================================================
> > >*192.168.0.2     69.25.96.13      2 u   83 1024  377    0.898
> > >-0.201   0.456
> > > 192.168.0.26    192.168.0.2      3 u  171 1024  376    1.588
> > >-1.921   0.416
> > > 192.168.0.27    192.168.0.2      3 u  204 1024  376    1.206
> > >2.312   0.008
> > > 192.168.0.29    192.168.0.28     4 u  323  256  166    0.110
> > >0.908   0.299
> > > GPS_NMEA(0)     .GPS.            0 l    -   16    0    0.000
> > >0.000   0.001
> > >     remote           refid      st t when poll reach   delay
> > >offset  jitter
> > >==============================================================================
> > >+192.168.0.26    192.168.0.2      3 u   67  512  177    0.100
> > >-2.753   0.374
> > >+192.168.0.27    192.168.0.2      3 u   67  512  377    0.055
> > >2.018   0.314
> > >*192.168.0.28    192.168.0.2      3 u  120  512  137    0.020
> > >-0.953   0.337
> > > GPS_NMEA(0)     .GPS.            0 l    -   16    0    0.000
> > >0.000   0.001
>
> According to ./ppstest the GPS works until I start ntpd.


Okay the ppstest is asserting and clearing but still no ntpq -p reach:
     remote           refid      st t when poll reach   delay
offset  jitter
==============================================================================
*192.168.0.2     69.25.96.13      2 u   12   64   77    0.141
1.222   0.564
 192.168.0.26    192.168.0.2      3 u   42   64   76    0.001
-0.109   0.506
 192.168.0.27    192.168.0.2      3 u    1   64   77    0.083
5.219   0.516
+192.168.0.29    192.168.0.26     4 u   15   64   76    0.001
0.478   1.144
 GPS_NMEA(0)     .GPS.            0 l    -   16    0    0.000
0.000   0.001




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