[ntp:questions] Stabilizing the drift file?

Juergen.Salm at siemens.com Juergen.Salm at siemens.com
Sun Nov 26 09:14:33 UTC 2006


Hi Dave.

> Assuming your system specification allows for up to 10 ms measurement
> error over two seconds, your script can result in a maximum frequency
> error of 5000 PPM. Golly.

With 10ms measurement error, we would never be able to fulfil the
requirement of less than 10ms offset between the blades. ;-(

However, the blades are communicating with each other via a gigabit
ethernet backplane.
The poll delay is usually less than 150us. And to cope with single
outliers, I use '-p 8' in the script. In addition, the script uses the
server timestamp information to calculate the duration of the
measurement period to be independent of the potentionally hight error
of the local clock. And I anyway have to trust the server.

Bye
 Juergen




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