[ntp:questions] Timekeeping broken on Windows XP with multimedia timer enabled (-M option)

Alan greigaln at netscape.net
Wed Jan 20 12:08:44 UTC 2010


I downloaded the latest prebuilt binary from Meinberg (4.2.4p4)and 
installed on XP Service Pack 3. NTPD was not only completely unable to 
keep the clock in synch but actually made things far worse with time 
drifiting backwards by up to a second every few minutes and NTPD 
continually stepping the clock forward with the "exceeds 500ppm message".

I then downloaded the pre-built 4.2.6 from Dave Harrt's site and it did 
exactly the same. Then I tried turning off the "-M" option and 
restarting (both versions). The clock quickly achieved synch to within a 
few milliseconds. The drift frequency was calculated at 4.764 (rather 
than above 500) and the jitter reduced to a few milliseconds. Now when I 
run certain applications the clock jumps by a few millseconds (which the 
-M option is supposed to cure but I can live with this under windows) 
but my question  is why is NTPD broken in my environment when installed 
withe the default Meinberg installation option of setting the timer to 
highest resolution? Anyone else seen this?

This on a dual core AMD-64 with WIndows XP Professional fully patched.




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