Date: Thu, 17 Jun 2004 02:42:01 +0100 From: "Martin O'Nions" <martin.o'nions@catch22.demon.co.uk> To: "'David Magda'" <dmagda@ee.ryerson.ca>, "'Harlan Stenn'" <Harlan.Stenn@pfcs.com> Cc: freebsd-stable@freebsd.org Subject: RE: NTPD and SecureLevel Message-ID: <026c01c4540c$496bd180$021f1fac@ironchurch.com> In-Reply-To: <A8F402E4-BFF6-11D8-AF71-000A95B96FF8@ee.ryerson.ca>
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It's configurable. By default, ntpd will step or 'jump' corrections = greater than 128ms and slew anything smaller. Since it's normally running continually in the background, I'd consider it unusual for ntpd to need = to make a >128ms correction except perhaps on boot (when any drift in the = CMOS clock will need to be rectified). You can however force it to always = correct time using slewing by specifying the -x option (bearing in mind it takes = 33 minutes to slew 1 second). You can also change the step threshold from = 128ms if you really feel the need, using the tinker command in ntp.conf IIRC. If your machine is going to be regularly powered down for a period, then = an ntpdate at startup seems reasonable. If it'll be running most of the = time though with ntpd active, it shouldn't be making anything more than very minor slewed corrections, albeit on a frequent basis. At least, that's how it's always worked for me... > -----Original Message----- > From: owner-freebsd-stable@freebsd.org [mailto:owner-freebsd- > stable@freebsd.org] On Behalf Of David Magda > Sent: 17 June 2004 01:39 > To: Harlan Stenn > Cc: freebsd-stable@freebsd.org > Subject: Re: NTPD and SecureLevel >=20 >=20 > On Jun 16, 2004, at 20:03, Harlan Stenn wrote: >=20 > >> ntpd(8) doesn't actually change the time by making it 'jump' to the > >> correct time; it slows down or speeds up the rate at which the = timer > >> runs at. > > > > Sometimes ntpd will step (jump) the time. >=20 > Yes, I've noticed that as well (it appears in my logs). AFAICT there's > a period of time in which NTPd needs to 'stabilize' and then it slews > the time after that point. It's been a while since I've looked into = the > NTP algorithm in detail though. >=20 > You may want to ask about it in the Usenet group > comp.protocols.time.ntp for details. >=20 > _______________________________________________ > freebsd-stable@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to = "freebsd-stable-unsubscribe@freebsd.org"
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