[ntp:questions] Loopstats jitter field mostly zero?

Dave Hart hart at ntp.org
Sat Nov 24 20:26:20 UTC 2012

On Sat, Nov 24, 2012 at 7:56 PM, David Taylor
<david-taylor at blueyonder.co.uk.invalid> wrote:
> I've just started the statistics collection on my Linux/RPi NTP server, and
> when plotting the jitter results I found that most of the values were zero.
> I don't see that on my Windows stratum-1 systems.  Is there a limit in the
> calculation of the jitter value recorded (to 9 decimal places) in the
> loopstats file.
> I really can't imagine that such a low-powered server is /that/ good -
> better than a nanosecond.

What version of ntpd is the embedded device using?  ntpq -c "rv 0
version" <target name/IP>

ntpd's internal jitter calculation is done using C floating "double"
which is at least 64 bits.  Is the value you see working down to zero
over time, or starting and staying at zero?  How close are the
exceptions the "most of the values" to 0 nanoseconds?

I will try to keep an eye out for your response, but my email time
budget is severely limited through the end of year.

Dave Hart

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