[ntp:questions] improving ntpd performance on Windows

David J Taylor david-taylor at blueyonder.neither-this-bit.nor-this.co.uk
Mon Mar 2 13:46:57 UTC 2009

Dave Hart wrote:
> I'm particularly interested in how it works on systems with 100 Hz
> system clock interrupts (10 msec period).  All my test flock are 64
> Hz.  This version (and my prior test versions going back weeks) tells
> you your system clock period in the event log or configured log file:
> Enjoy,
> Dave Hart


Dave Hart asked that I post this information:

Very briefly, I happen to have a 100Hz system, and have been playing with 
the improved version of ntpd.exe on a Windows 2000 system.  Working with 
Dave, we found that it did have some issues, and it seems that these 
issues have probably been resolved by setting the sample interval to 26 
milliseconds instead of the default 43 milliseconds.

Although with a Windows XP or later system, you could do this by setting a 
System environment variable:


String value:

You would do this by right clicking on my computer and pick properties. 
Use the Environment Variables button in the Advanced tab of the Computer 
Properties dialog, and be sure to add a System variable rather than a User 

However, in a Windows 2000 system, it seems that the environment is not 
read again when your stop and restart a service, so Dave advised me to run 
ntpd.exe interactively, so I ended up with a command file like:

CD <where-ntpd.exe lives>
ntpd -n -g -c "c:\ntp\ntp.conf" -M

I hope that may help those of you testing this rather good new version.


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