[ntp:questions] SetSystemTimeAdjustment() on Vista

johumohu at yahoo.com johumohu at yahoo.com
Tue May 19 19:23:19 UTC 2009

Anybody ever tried to use SetSystemTimeAdjustment() on Vista?

I tested the accuracy ot the system time on my laptop. During about 6
hours, the time gets about 1 second too fast. On the basis of the
description of SetSystemTimeAdjustment(), the TimeAdjust should be
changed from the default 156001 to 156008. But 156008 makes the time
too slow. I tried 156002 and it is still too slow, it seems like
156001.5 would make it even but you cannot use fractions. In other
words, the default value 156001 seems to be the best choice. The
TimeIncrement is 156001. Any insight on this?

Also, one thing is not clear. The time adjustment is done at each
interval identified by TimeIncrement which is fixed  15.6001
millisecond. My question is what happens when the system time is
updated every 1 millisecond, because on my laptop system time is
updated mostly every 1 millisecond as long as there is some input
activity at keyboard or mouse. Does it mean Vista waits until the full
15.6001 millisecond is reached when using TimeAdjust?

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