[ntp:questions] Have Pi, have GPS = low powered NTP server?

Dave Hart hart at ntp.org
Thu Jun 7 16:01:01 UTC 2012


On Thu, Jun 7, 2012 at 10:30 AM, DaveB <g8kbv at uko2.co.uk> wrote:
> pi at raspberrypi:~$ ntpq -p
> remote          refid       st t when poll  reach  delay  offset  jitter
> ========================================================================
> *192.168.42.24  .GPS.        1 u  362  1024 377    0.563   0.669  0.284
>  time.xilo.net  82.219.4.30  3 -   5h  1024   0   21.571  13.885  0.000
>  dns0.rmplc.co 195.66.241.3  2 -   5h  1024   0 2019.75  -1000.8  0.000
>
> If those delay/offset and jitter figures are in milli seconds (?) could
> that be down to the USB hosted LAN port on the Pi?  The same figures for
> the BSD box at 192.168.42.24 are 0.000 0.004 and 0.002 respectively, I
> just remoted into that and checked.

Yes, having your network behind a USB adapter is going to degrade
performance compared to a PCI-connected NIC.  A half-millisecond delay
is quite high for 100Mbit LAN.  Offset and jitter in the same range
are to be expected.

The output of:

ntpq -c "rv 0 version precision"

would shed a bit more light on which ntpd version and the time to read
the clock on that system.

Cheers,
Dave Hart


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