Michael, [EMAIL PROTECTED] wrote:
> Thanks for the detailed reply Martin. > It sounds as if MS's W32Time/TimeServ actually does a slightly better > job. > According to > http://support.microsoft.com/kb/q246145/ > W32Time is aware of leap seconds and will try to step the time shortly > after by polling the server, but with a 15 minute spread so that the > NTP server doesn't get flooded. I've also tested w32time (from W2kSP4) now and indeed it does a much better job in this case: yyyy-mm-dd hh:mm:ss.msec dt1[ms] dt2[ms] dt1-dt2 tick (corr) [hns] -------------------------------------------------------------------------- 2005-12-31 23:59:57.289: 1000.0000 999.9961 +0.0039 156250 (+0) 2005-12-31 23:59:58.289: 1000.0000 999.9977 +0.0023 156250 (+0) 2005-12-31 23:59:59.289: 1000.0000 999.9977 +0.0023 156250 (+0) 2006-01-01 00:00:00.289: 1000.0000 999.9943 +0.0057 156250 (+0) 2006-01-01 00:00:01.148: 859.3750 999.9972 -140.6222 78125 (-78125) >< 2006-01-01 00:00:01.648: 500.0000 999.9942 -499.9942 78125 (-78125) >< 2006-01-01 00:00:02.273: 625.0000 999.9968 -374.9968 156250 (+0) >< 2006-01-01 00:00:03.273: 1000.0000 999.9954 +0.0046 156250 (+0) 2006-01-01 00:00:04.273: 1000.0000 999.9986 +0.0014 156250 (+0) 2006-01-01 00:00:05.273: 1000.0000 999.9985 +0.0015 156250 (+0) 2006-01-01 00:00:06.273: 1000.0000 999.9949 +0.0051 156250 (+0) This has been recorded using a simple program which does the following in a loop: - read the system time - read the performance counter - read current tick adjustment - process the values - sleep for 1000 milliseconds Output contains the system date and time (the time zone has been set to UTC here), then dt1 which is the difference between the last 2 readings of the system time, then dt2 which is the difference between the last 2 readings of the performance counter, and finally the current tick adjustment value and the difference from the standard tick adjustment value. We can see that immediately after the point of leap second insertion w32time slews the system clock over 3 or 4 seconds to account for the offset. I could also see, however, that normally the tickadjustment value is set to its default value (156250, i.e. 15.6250 millisecond timer tick interval) all the time which means that w32time does not discipline the system time continuously like ntpd does. Martin -- Martin Burnicki Meinberg Funkuhren Bad Pyrmont Germany _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
