[LinuxPPS] ntpd synchronization issues

[Miroslav Lichvar]

On Sun, Aug 08, 2010 at 06:55:08PM +0200, Felix Joussein wrote:
> # PPS1
> server 127.127.22.1 iburst minpoll 4 maxpoll 4 prefer
> fudge  127.127.22.1 stratum 0 refid ATOM flag3 1

"flag3 1" means ntp should enable the kernel PPS discipline, but
current kernels don't have a PPS discipline included yet. This is
probably the reason why you see such big difference in initial
synchronization when compared to the old PPSkit.

Search the archives for Alexander's patches posted here week ago,
amongst other things they add a PPS discipline.

Please note that with fast convergence you lose some accuracy. If this
is a concern, you might want to consider having two ntp configs, one
with "flag3 1" that will be used only for few minutes to settle down
the frequency and offset and a second config not using the PPS
discipline which will take over.

-- 
Miroslav Lichvar