[LinuxPPS] Why is my ATOM clock a falseticker?

[Cirilo Bernardo]

On Sat, Jan 31, 2009 at 9:46 AM, Paul Simons <paul at thesimonet.org> wrote:
> Oops, here is the relevant section:
>
> server 127.127.22.1 minpoll 4 maxpoll 4 # ATOM (PPS)
> fudge 127.127.22.1 flag2 1              # Use the "clear" edge of the signal
>
> # "PPS pulses are usually short, and the leading edge is the on-time mark,
> # so by looking at the time of two adjacent edges with cat
> /sys/class/pps/pps1/{assert,clear},
> # you can see which one leads the other."
>
> server 127.127.5.0 prefer               # TrueTime clock
> #No fudge
>

I suspect the problem is with putting 'prefer' into the 127.127.5.0
source.  If that is an ASCII string then there will be a lot of jitter
in it and may have an unwanted effect on NTP.  If that is a problem
then ntp or Linux has a bug because the interval between PPS pulses
should be much more stable than the ascii string put out by a clock.

What is your setting for CONFIG_HZ in the kernel options?

- Cirilo