[ntp:questions] Re: Best way to harness multiple stratum 1 servers

Richard B. Gilbert rgilbert88 at comcast.net
Thu Apr 6 18:48:23 UTC 2006


Terje Mathisen wrote:
> Richard B. Gilbert wrote:
> 
>>
>> I believe I have read the PHK has modified the ntpd PLL for use with 
>> refclocks such as GPS and Cesium.  I don't know PLL design from a hole 
>> in the ground but he might have improved the design for that specific 
>> purpose.  It's worth looking into!!
>>
>> BTW, what hardware and O/S are you using for this project?  Solaris 
>> 8/SPARC keeps time to a precision of one microsecond.  I don't know of 
>> any hardware/software that supports a higher precision but there may 
>> well be some.
> 
> 
> AFAIK, Sun was the first to implement nanosecond kernel time resolution, 
> it is definitely a standard part of all FreeBSD systems, and an absolute 
> requirement if you want sub-microsecond GPS/Cs performance.
> 
> Ulrich Windl have maintained a set of patches to Linux to get ns there 
> as well.
> 
> Terje

Terje,

Where does Solaris keep the nanoseconds?

The precision shows as "-21" or about 1 microsecond and, indeed, the 
smallest difference between two consecutive calls to gettimeofday() is 
one microsecond.

Is there some documented and supported way to access the nanosecond part 
  of the time?




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