[ntp:questions] OS recomendations for stratum 2 clocks

Brad Knowles brad at stop.mail-abuse.org
Wed Sep 7 21:01:11 UTC 2005


At 4:17 PM -0400 2005-09-07, Joshua Coombs wrote:

>  Using standard PC hardware, and no directly connected reference clocks
>  as limitations, is there a general recommendation for OS on a box that
>  will be dedicated to NTP?  My current background has me most comfortable
>  with FreeBSD, but if using a true RTOS will give me any tangible
>  improvements in the quality of time pushed out of these boxes (stratum
>  issues not withstanding) then I'm willing to learn a new setup.

	Choosing the right hardware platform, with the right kernel 
configuration, Poul-Henning Kamp has gotten FreeBSD configurations 
down to the nanosecond range for accuracy -- note that most of the 
rest of us have to make do with accuracy down only as far as the 
millisecond range.

	Of course, he had a good-quality Stratum-1 GPS directly 
connected, but the same hardware platform/kernel configuration should 
likely do as well as can reasonably be expected for a Stratum-2 time 
server without any directly connected refclocks.


	You could probably do the same or somewhat better with an RTOS, 
but the real kicker is that you have to be very careful with your 
hardware and OS configuration -- just any random PC ain't gonna be 
able to get you anywhere close to that level, no matter what the OS 
looks like.

-- 
Brad Knowles, <brad at stop.mail-abuse.org>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

     -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
     Assembly to the Governor, November 11, 1755

   SAGE member since 1995.  See <http://www.sage.org/> for more info.



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