[ntp:questions] refclock on Windows graphs

Danny Mayer mayer at ntp.org
Sat Mar 21 21:31:13 UTC 2009

Unruh wrote:
>> most accurate estimate of the remote clock.  The new interpolation
>> scheme converts a counter to a timestamp by selecting from a history
>> of recent correlated OS time & counter values the one which calculates
>> the latest timestamp, based on the observation that all error
>> associated with the counter having been sampled some indeterminate
>> amount of time after the OS time advanced a tick (or 10-15ms) is
>> negative (resulting in erroneously earlier timestamps).
> I will leave to you the decision as to the cost-benefit ratio of this
> strategy to try to overcome the inherent limitations of Windows timing.

The inherent limitations of Windows timing are no different from that of
Unix except in Unix you can update the kernel. It has become far more
important in recent years to for Microsoft to do a better job of timing
since that heavily affects gaming programs though access to the QPC has
been around a long time.


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