Date: Thu, 06 Apr 2000 20:24:53 -0500 From: David Kelly <dkelly@hiwaay.net> To: Sheldon Hearn <sheldonh@uunet.co.za> Cc: Greg Black <gjb-freebsd@gba.oz.au>, FreeBSD-questions@FreeBSD.ORG Subject: Re: Kernel adjustment for clock drift Message-ID: <200004070124.UAA11635@nospam.hiwaay.net> In-Reply-To: Message from Sheldon Hearn <sheldonh@uunet.co.za> of "Thu, 06 Apr 2000 13:35:50 %2B0200." <13835.955020950@axl.ops.uunet.co.za>
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Sheldon Hearn writes: > > > On Thu, 06 Apr 2000 20:09:50 +1000, Greg Black wrote: > > > I have a machine that drifts about 7 seconds a day and I'd like to > > tweak something in the kernel to keep it closer to the truth. The > > clock gets corrected once a day by ntpdate, but I'd like to avoid such > > big adjustments. > > This is not a direct answer to the question you asked. :-) > > Is it impossible for you to > > a) run ntpdate at more regular intervals > > or > > b) use ntpd, also in the base system? > > Presumably you're talking about a frequently unconnected host using > automatic ppp? If so, you could run ntpdate out of ppp.linkup. > Alternatively, you could run ntpd and set up ppp's dial and active > filters so that ntpd's synchronization attempts do not cause a dial > attempt nor keep an existing connection alive. See my other posting to this list. I ran xntpd for years on a dialup connection. Connected an hour or two or three per day. Xntpd doesn't seem to have any problems resuming when the connection resumes. Xntpd *does* spit a message into syslogd whenever it first loses its connections. Observed xntpd disappeared with FreeBSD 4.0 and now we have ntpd. Seems to work exactly the same. I didn't change anything. One "gotcha" is that xntpd didn't like to be started unless it had a nework connection. So don't put it in an rc startup file. I start ntpd now by hand first time I think of it when connected after a reboot. The other "gotcha" is that you don't want [x]ntpd keeping your dialup ppp link active. I manually invoke pppd and kill it. There are filtering rules for pppd and ppp so auto-dial will not be triggered by ntp. [X]ntpd will calculate your system clock drift and apply pre-emptive adjustments to keep it tuned. Looks like ntpd has been adjusting my clock back 1 second about once per day when its connected. Its only had 4 days since I changed over from xntpd and the driftfile value may have changed units. -- David Kelly N4HHE, dkelly@hiwaay.net ===================================================================== The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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