[ntp:questions] Time server question

Thomas Laus lausts at acm.org
Fri Jun 21 13:14:41 UTC 2019

On 2019-06-21, David Woolley <david at ex.djwhome.demon.invalid> wrote:
> On 21/06/2019 12:26, Thomas Laus wrote:
>> Will either isolation solution have direct access to the computer
>> CPU?  The GPS clock will need the ability to directly adjust the
>> frequency of the CPU to achieve expected results for a Stratum 1
>> serve
> I'm not aware of anything in ntpd that directly adjusts the CPU 
> frequency and there generally isn't any fine grained way of doing that. 
> ntpd normally works by adjusting how many cycles of a fixed frequency 
> represent a certain time period, and that is a software operation.
I guess that I should have stated this reply a little differently.  I
meant to say that ntpd will need direct access to the hardware that
it runs on.  That means a hardware serial port for pulse per second
and the running system clock frequency.  The ntpd program does not
perform well when running on a virtual machine nor in a isolated
security environment similar to a freebsd jail.  My advice to the
original poster is to get ntpd running as a stratum 1 source and
then connect it to the internet with the fewest number of inter-
mediate hops in between.  I doubt that this is possible if the
Stratum 1 time source can be connected through any buffer device
to the internet and still serve Stratum 1 time.

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