[LEAPSECS] Leap second smearing test results

[Zefram]

Martin Burnicki wrote:
>I've run some more tests with smearing of leap seconds,

These new ones, with variable polling interval on the client, are much
more useful than the former ones with fixed polling interval.  It seems
to me that these measurements should concentrate on clients with default
settings, because if one is able to configure the client to better follow
the smear then one could easily do an even better job by configuring
the client to follow an honest server and to introduce the smear itself.
Only the case where the client can't be specially configured is really
relevant to the concept of introducing the smear upstream.

I'd like to see a run of this client type with the 24 hour smears
that you used earlier, or of a fixed-polling-interval client with the
new 10 hour smears, so that variable polling interval can be directly
compared against fixed polling interval.  I'd interpreted your earlier
tests generally based on the poll=10 client, in the expectation that
the default variable polling interval would behave similarly, but it's
not clear whether the reductions of polling interval that you see would
result in a significant difference in performance.

It is strange that the polling interval varies so much more with the
linear smear than with the sinusoidal smear.  I would have expected them
to remain stable at poll=10 for the bulk of the smear, after they've
recovered from the initial frequency change.  There is a point 2.5
hours into the smear where all the clients have returned to poll=10;
can you explain why they reduce it again after that?

Also strange that the three clients had such different reactions to the
end of the linear smear, having been so similar in their reactions to
the start of it, and similar in all parts of the sinusoidal smear.

It is interesting that when the server suggests a smaller poll interval
the shape of the smear makes a big difference to the tracking accuracy.
This is much like the difference that we intuitively expected the shape
to make in the first place.

-zefram