[ntp:questions] ntp-4.2.6p5 on Win 7 x64

Martin Burnicki martin.burnicki at meinberg.de
Thu Jul 24 10:14:21 UTC 2014

Nick wrote:
>> What have I missed?
> Having read all the recent posts I have installed 4.2.7p450 binary from
> satsignal.eu to run with -M switch.

Have you also tested without -M switch?

> Disabled the following drivers;
> - delta 44 soundcard
> - pe0fko Si570
> - com0com
> Everything else looks standard; I'm using the on board Intel G31 graphics,
> and the disks use DMA.
> The only non-standard services are Adobe Update and NTPD.
> The box is very lightly loaded.
> ntp runs well on Mint 17 and the drift is reported to be -17ppm.
> ntp does not run well on Win 7 x64 and the drift is reported to be +493ppm.
> What makes ntpd think that the frequency error on Windows is +493?

 From my experience such frequency error under Windows is simply wrong 
because the time stamps read from the system time provide too much jitter.

What's the output of "ntpq -p" in this case? I'm assuming the numbers 
both for jitter and offset are very lare, eventually more than 1000 ms.

> wclkres64 reports that performance counter frequency is 2.734MHz.  The QPC
> execution time for 1000 calls varies between 26ns and 37ns.

This should only matter at all if ntpd interpolates the system time 
using APC timer callbacks and QPC calls.

ntpd-dev should not use interpolation at all if it detects that the 
system time increments in 1 ms steps. If interpolation is *not* used 
then after startup of the NTP service there should be a message in the 
Windows application event log reading "using windows clock directly".

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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