On Wed, Sep 28, 2011 at 05:20 UTC, David J Taylor wrote:
* Added the NTPD_TICKADJ_PPM environment variable for specifying
baseline
clock slew on Microsoft Windows
Does NTPD_TICKADJ_PPM allow the use of clocks which are more than 500
ppm
out? Sorry if I missed any earlier discussion on this (and I don't run
Linux). How does one go about determining the value to set - just
guesswork?
Yes, it should, just as tickadj and similar capabilities do for POSIX
systems. You can determine the value to set any way you like, from
measurement to guesswork to dart throws. The adjustment is done at a
low level in the Windows ntpd port, invisible to the portable ntpd
code, but is expressed in PPM with the same sign ntpd uses. If ntpd
is bouncing up against the +500 PPM limit occasionally, using a
positive NTPD_TICKADJ_PPM should improve the situation.
I'm interested because someone has just reported problems with NTP on a
system which gain (or loses) 1 second in 10 minutes! 1 part on 600!
This
adjustment could be most helpful.
It might help, I hope so. Hopefully the clock rate error is
consistent enough that after the extreme compensation, it stays well
under 500 PPM.
Cheers,
Dave Hart
Dave,
That's brilliant! I didn't know about it, and I don't know how I missed
it. Anyway, it's now found, so I've passed on the information and
recommended this version:
http://davehart.net/ntp/win/x86/ntp-4.2.6p4-win-x86-bin.zip
The chap involved is a C programmer on Windows, so he should be able to
handle it OK. Of course, if the problem is missed interrupts rather than
a simple clock-rate issue, it may not help at all. I had not involved you
earlier as I feel I've loaded you enough already, and had hoped to solve
this problem directly.
Cheers,
David
--
SatSignal software - quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
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