Rob,
With due respect, I don't think you know what you are talking about. The
original discipline loop described in rfd1305 was refined as described
in my 1995 paper and further refined over the years since then. For each
and every refinement a series of tests, both in simulation and in situ,
were performed with initial offsets up to +-500 PPM and +-100 ms to
verify correct behavior with the original parameters. The daemon loop is
required to operate over a time constant between 8 s and 36 h, which is
an extremely large range as verified by ongoing configurations here.
The kernel loop is designed to replicate the daemon loop over a much
narrower range between 8s and 1024 s. The ideal poll interval is 16 and
64 s matching the Allan intercept as described in the literature. It was
first implemented for the Alpha in 1992 and refined as described in my
1995 paper and not changed since then. Correct behavior must be
confirmed by an experiment such as I suggested in a previous message.
Sound engineering principles project that the behavior at other time
constants will be as I described. If you don't believe those principles,
you are not exercising sound engineering judgment.
Dr. Dave
Rob wrote:
Miroslav Lichvar <mlich...@redhat.com> wrote:
On Wed, Jun 30, 2010 at 10:00:06PM +0000, David L. Mills wrote:
Is there somebody around here that understands feedback control
theory? You are doing extreme violence to determine a really simple
thing, the discipline loop impulse response. There is a much simpler
way.
It was a demonstration of what clknetsim can do. You may be able
to predict the result, but I'm not. I think being able to verify a
theory with simulations is always a good thing.
Mr Mills is of the school that says "the design predicts that the
program behaves like that, and the implementation has not changed
for 10 years, so it must be correct". While I normally adhere to the
same principles, it happened just a week or two ago that he had to
admit that there was a bug in code that he firmly believed was
correct and that an observed behaviour "could not possibly happen".
So I agree with you that it never hurts to test something that theory
has already proved to be correct. Maybe the actually released program
does not really implement the mechanism that was designed, without
the programmer knowing it.
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