[ntp:questions] Re: -M ntpd Option

Heiko Gerstung heiko.gerstung_removeme_ at meinberg.de
Wed Jun 28 06:48:31 UTC 2006


Charles Elliott schrieb:
> When the installer installed nptd on my Win XP SP2 machine as a service it 
> added the -M option.  I cannot find where this option is documented.  Does 
> anyone know what it does?
> 
> Charles Elliott 
> 
> 

This switch has been added by my colleague, Martin Burnicki, and is only 
available in our ports of the ntpd for Windows. The necessary additions 
to the sourcecode of ntpd have been submitted to the ntp project and - 
as far as I know - will be added in one of the upcoming dev releases. It 
is included in our "xmas"-Edition, the currently available version on 
our homepage (see http://www.meinberg.de/english/sw/ntp.htm). Our time 
server monitor application 
(http://www.meinberg.de/english/sw/time-server-monitor.htm) detects this 
and allows you to switch it on or off without directly messing with the 
registry.

As David already explained, the switch enables the Windows Multimedia 
Timer when ntpd starts. If this is not done and you start an application 
that needs it, it will turn it on and ntpd will experience a significant 
time jump (20-40ms) at that point. After you closed the last application 
using the MMT, the time jump will happen again - in the opposite direction.

Quite a number of applications make use of the MMT, including Quicktime, 
Windows Media Player and several browser plugins.

We did not experience any significant drawbacks when enabling the MMT at 
the start of ntpd, therefore it makes sense to switch it on permanently 
and avoid the described time jumps.

Kind regards,
Heiko



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