[ntp:questions] Win7: ntpd adjusting time backwards

Jeroen Mostert jmostert at xs4all.nl
Thu Dec 13 05:53:57 UTC 2012

On 2012-12-13 02:41, E-Mail Sent to this address will be added to the BlackLists 
> Jeroen Mostert wrote:
>> GetSystemTimePreciseAsFileTime() is available, but most
>>   of our machines are still Windows Server 2008/2008 R2
>>   (even with some 2003 server still hanging around).
>> On the physical machines, GetSystemTimeAsFileTime() will
>>   get the time with 1 ms resolution since the MM timer
>>   will be enabled, which is good enough.
>> On the virtual machines, however, GSTAFT cannot do better
>>   than the 15.625 ms resolution it has by default.
> ntpq -c "rv&0 precision"
>   should give a clue how close you can expect to get on a given machine.
I assume you mean 'ntpq -c "rv 0 precision"'. Your command gives me an error.

I'm not sure that means much. On the physical machines I get precision=-10, 
which makes sense since the multimedia timer is on and the resolution of GSTAFT 
is 1 ms. On the virtuals, however, I get -19 (ntpd 4.2.6p5) and -20 (ntpd 
4.2.7p310). That may reflect the numerical precision of the interpolated clock, 
but that doesn't mean actually reading it with that precision is useful.


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