[ntp:questions] Preffered OS for a GPS based stratum 1

Kevin Oberman oberman at es.net
Fri Oct 31 17:48:13 UTC 2008

> From: Terje Mathisen <terje.mathisen at hda.hydro.com>
> Date: Fri, 31 Oct 2008 08:59:06 +0100
> Sender: questions-bounces+oberman=es.net at lists.ntp.org
> Spiffed wrote:
> > I've dug up an Oncore GT+ GPS receiver, matching antenna, and PPS 
> > stretching converter box. WinOncore shows a 'Time Solution one sigma' of 
> > 38ns, so it seems to be an acceptable ref clock for my purposes.
> > 
> > After surveying the computing hardware available, a Sun Ultra10 seems to 
> > keep the best time and is otherwise unused.
> > 
> > What OS do you recomend for the Ultra? Off the top of my head, I'm 
> > considering Solaris (is there PPS support in Solaris 10?), FreeBSD or 
> > NetBSD. My understanding is Linux 2.6 PPS support is rough at best.
> FreeBSD is the canonical OS for a PPS box, search for some of phk's 
> articles on this subject!

Seconded. FreeBSD has taken ntp and timing as a priority for a very long
time. I know that back in the days when BSD was still being developed at
Berkeley, they counted the instructions used by the PPS kernel code and
then used the clock frequency to correct the time for that delay.

N.B., with any system, don't expect really good time if the CPU uses
power management tools that change the frequency of the CPU while NTP is
running. Your probably better off with a single CPU system.
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751
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