On Fri, Dec 9, 2011 at 17:27, Miroslav Lichvar <[email protected]> wrote: > What resolution has the clock frequency adjustment? I'm reading > about the SetSystemTimeAdjustment function and the adjustment is in > 100-ns units applied over an lpTimeIncrement interval. If the interval > is too short I suspect this could also limit the time and frequency > accuracy of the system clock.
Clock interrupt period 15.600 msec (startup slew 19.5 usec/period) Windows clock precision 1.001 msec, min. slew 6.410 ppm/s That's from typical ntpd startup on Vista and later. SetSystemTimeAdjustment operates here in 100ns units per 15.600 msec fictional tick. The result is a unit adjustment to the SetSystemTimeAdjustment argument results in a 6.4 PPM rate change. sys_residual carry allows finer adjustments over multiple seconds. Cheers, Dave Hart _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
