[ntp:questions] Re: How to force ntpd to set time first time if clock is withhin +-128ms range

David L. Mills mills at udel.edu
Wed Sep 10 19:56:47 UTC 2003


Barbjit,

You can force ntpd to set the time directly and avoid slew upon startup
by simply removing the ntp.drift file. However, you will not like the
result, as it will take hours to recompute and refine the intrinsic
frequency correction, and it will not necessarily result in accuracy
within the millisecond at or shortly after startup.

The NTP clock discipline is essentially a feedback loop with a carefully
contrived impulse response. If you really must bound the residual error
quickly, you will have to (a) use kernel support to allow discipline at
every timer interupt and (b) re-engineer the impulse response for a
quicker risetime. This would mean reducing the poll interval much below
the 16-s lower limit now required by the adjustment process.

Dave



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