[chrony-dev] Visualization of clock control

[Miroslav Lichvar <mlichvar@xxxxxxxxxx>]

Hi,

I wrote a tool to visualize the data generated by the clknetsim
simulator and I thought some of you might find it interesting. The
goal was to show how a clock is controlled by NTP client and at the
same time see its offset from true time and the NTP measurements (the
actual offset and delay seen by the client).

Here are some example runs of the tool captured to animated gifs:
http://mlichvar.fedorapeople.org/clknetsim/chrony_ntp/vis/visclocks_10us.gif
http://mlichvar.fedorapeople.org/clknetsim/chrony_ntp/vis/visclocks_100us.gif
http://mlichvar.fedorapeople.org/clknetsim/chrony_ntp/vis/visclocks_1000us.gif

The simulations were done with a clock wandering at 1 ppb/s,
10/100/1000us network jitter with exponential distribution and the NTP
clients were configured to use 64s polling interval.

The white line is the reference clock. The red line is the clock
controlled by ntp and green is chrony. The blue lines are the NTP
measurements made by chrony. Both clients were getting the same data,
but the polling intervals were not exactly the same so the frequency
changes in the red line don't match exactly with the blue lines.

The tool is included in the clknetsim git as visclocks.py. It also has
a game mode, where you control the frequency and phase of the clock by
mouse and you can try to beat the other clients. :)

-- 
Miroslav Lichvar

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