[ntp:questions] Allan deviation survey

David L. Mills mills at udel.edu
Sat Sep 11 15:39:12 UTC 2010


David,

I have no idea where you are coming from. At my feet are two GPS/CDMA 
time servers running embedded Linux systems. I have two more on campus 
plus two dedicated Unix machines connected to GPS receivers. NIST has 
about a dozen dedicated time servers running FreeBSD. USNO has about a 
dozen running HP-UX. The NRC in Canada runs at least two of them, as 
does an unknown number in Europe, Japan and Australia. There is even one 
in Antarctica and occasionally one or two in space and oone on the 
seafloor of the Pacific Ocean. Maybe they are abnormal in your view, but 
they are the ones I am concerned about and they are the ones the Allan 
deviation analysis is intended for. If you want to run NTP in a virtual 
machines, the performance will depend on many factors, but none of which 
have to do with Allan deviation.

Dave

David Woolley wrote:

> David L. Mills wrote:
>
>>
>> I beg to differ. All the machines I used are PCs or similar 
>> workstations. They really and truly behave according to an exponential 
>
>
> As you note in another reply, you seem to use them in a way that is 
> abnormal for most users of NTP, i.e. as dedicated real machines in 
> well controlled environments.
>
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