Richard,
I know why they changed the design and why Linux did, too. It allows
quick adjustments with large offsets when done manually. From what
evidence I have, they use an exponential algorithm, which is simple to
implement. However, the extra pole that algorithm introduces conflicts
with the NTP PLL. There really should be a way to turn the algorithm on
and off, but I don't expect much sympathy from the kernelmongers.
Dave
Richard B. Gilbert wrote:
[EMAIL PROTECTED] wrote:
Richard,
The overshoot is the result of a misdirected Solaris/Linux design of
the adjtime() system call. The design added a poll to the transfer
function in order to speed the response to a programmed offset. The
result completely torpedoes the PLL transient response and there is
nothing that can be done to correct it in ntpd itself. What you see is
what you get. The problem is most apparent with large initial
frequency offsets, which are guaranteed to result in pinball behavior.
Note the overshoots do not occur in FreeBSD or Tru64, which have a
reasonable design.
Dave
Dave,
Have you reported this to Sun as a bug?
It seems to me that they should fix it and, perhaps, create a new
function, say, adjtime_fast() that would add the functionality without
breaking ntpd. It might not get you anywhere but he who does not ask
does not get!
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