Date: Thu, 16 Dec 1999 18:51:27 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: mjacob@feral.com Cc: Ollivier Robert <roberto@eurocontrol.fr>, "FreeBSD Current Users' list" <freebsd-current@FreeBSD.ORG> Subject: Re: HEADSUP: ntp4 to replace xntpd Message-ID: <16818.945366687@critter.freebsd.dk> In-Reply-To: Your message of "Thu, 16 Dec 1999 09:34:50 PST." <Pine.BSF.4.05.9912160934230.23583-100000@semuta.feral.com>
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In message <Pine.BSF.4.05.9912160934230.23583-100000@semuta.feral.com>, Matthew Jacob writes: > >Huh? What about the impact on all ntp.conf files? Or is this seamless? I was just about to start to compose an email with some info on this one when you email arrived. /etc/ntp.conf is the same unless you have a refclock. If you have a refclock you need to revisit your setup. About NTPv4 in general I can say that a lot of things have changed under the hood. Between the two of us Dave Mills and I have managed to get the "nanokernel" to act sensibly in the domain inside +/- 1usec which the old one didn't. (See http://gps.freebsd.dk for what kind of performance this can result in, given appropriate hardware). A lot of changes in the "control" code in ntpd has also changed, and as far as I can tell for the better all around. There is support for *very* long poll intervals (18hours I belive a lot cheaper if you sync by dialup) and burst mode which is more suitable for dial-on-demand kind of lines. There is a new API for PPS kind of signals (I'm also partly guilty here, but I must admit that I think the result is far too rococco for my taste). One thing which is new, is the initial synchronization: it can look broken, but it isn't. You will likely see something like this: 1. Ntpd starts 2. Home in on some server, steps the clock to zero offset. in the process we loose sync again. 3. Catch sync again. Very light and slow adaptation of frequency the clock slowly drifts off to +/- 128msec. 4. Clock is steped again and frequency set to slope of the drift from step 3. 5. Business as usual. Depending on your clock step three can take hours to complete, the better your clock the longer it takes. Dave Mills old rule of thumb applies even more than before: Only tweak your ntp.conf right before lunch. That gives it 24hours to settle before you fiddle it again. You can find much more about NTPv4 on www.ntp.org -- Poul-Henning Kamp FreeBSD coreteam member phk@FreeBSD.ORG "Real hackers run -current on their laptop." FreeBSD -- It will take a long time before progress goes too far! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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