[ntp:questions] Re: ntpd PLL and clock overshoot
Richard B. Gilbert
rgilbert88 at comcast.net
Mon Oct 9 18:25:58 UTC 2006
user at domain.invalid wrote:
> 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.
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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