[ntp:questions] refclock on Windows graphs

David J Taylor david-taylor at blueyonder.neither-this-bit.nor-this.co.uk
Wed Mar 18 10:38:28 UTC 2009

Dave Hart wrote:
> The 150us offsets are while slewing to try to catch up with the 3ppm
> frequency shift as the heat comes on.  I have to imagine a Windows PC
> with a more stable oscillator (lower temperature coefficient to
> frequency) would do better, though I'm not deluding myself that it
> would match the performance of FreeBSD, with its advantage of knowing
> the precise relationship between the counter and the system clock.

Yes, it would be nice to have a more stable crystal in that system. 
Agreed on the comparison with FreeBSD.  Isn't there an NTP simulator where 
someone could model jitter and offset against a 2.5ppm sinusoidal or 
triangular frequency swing?

> I have no familiarity with 4.2.0 but keep in mind it's even older than
> 2005, that's the FreeBSD release date and they were not keeping up wth
> NTPv4 builds very closely then.  From my perspective comparing its
> performance to the new Windows stuff, it would be awfully nice to get
> 4.2.4p6 on your FreeBSD box.  There are plenty of helpful FreeBSD
> wizards hanging around here who could help with any issues you have
> building the reference implementation and installing it in place of
> the system-provided one on that FreeBSD box.  At least I think they
> would, but given your treacherous discussion of moving away from
> FreeBSD in favor of Windows maybe you'd get the cold shoulder ;)

Yes, it would be most interesting to know whether 4.2.2p6 has traded 
offset for the sake of jitter.  I don't propose to make any changes on a 
working box right now, though.

>> I have checked for a temperature monitoring SNMP plug-in, but not
>> found a compatible one as yet.
> SNMP is ideal, but anything that could read a temperature that had a
> high degree of correlation with your osciallator's crystal temperature
> would be enough to build upon.  I'm afraid anything built in to your
> hardware (like CPU core temp) is not well-enough correlated the
> crystal temp.
> Cheers,
> Dave Hart

I'm happy to play if anyone knows anything for a Dell 4400.  It needs to 
have an interface I can read - either via SNMP or a Perl script so that I 
can get it into MRTG to plot.  Using the WMI/MSAcpi_ThermalZoneTemperature 
approach doesn't work, so I'm probably stuck.


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