Brian Utterback wrote: <snip>
> There is an algorithm for determining the optimal poll interval > given the frequency wander over time, and the jitter (error) > in the offset measurements. This is called the "Allan intercept", > after the late comic Fred Allen. No, wait, that can't be right. > Just a sec... > > Sorry, the Allan intercept is named for the still-very-much-with-us, > Mr. David W. Allan, timekeeper extraordinaire. > David Mills has some interesting stuff on his web site about Allan intercept. I was reading http://www.cis.udel.edu/~mills/database/papers/allan.pdf. I have to go over it more to understand it. > So, there you have it. I hope that helps you to understand how > a longer poll interval can lead to a more accurate clock, and > why it is a good idea to let NTP decide what the best poll interval > actually is. > > > I have noticed that with bad clock hardware, such as a SUN Sparc, > > it does a poor job of controlling the poll interval. > > > > Them's fightin' words. There's good Sparc hardware and bad Sparc > hardware. There's good software and bad software. I hope you > aren't casting aspersions on the whole product line are you? I worked at a place with 70 or so Sparc 2s. The clocks drifted badly which is why I got into messing with the maxpoll parameter. That was an informative post. I'll have to do more reading on the algorithms. - Mooron _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
