Date: Sat, 28 Mar 1998 10:51:52 -0600 From: Dan Nelson <dnelson@emsphone.com> To: dennis <dennis@etinc.com> Cc: hackers@FreeBSD.ORG Subject: Re: Setting time from bios Message-ID: <19980328105152.A17527@emsphone.com> In-Reply-To: <3.0.32.19980328105113.00e3b550@etinc.com>; from "dennis" on Sat Mar 28 10:51:14 GMT 1998 References: <3.0.32.19980328105113.00e3b550@etinc.com>
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In the last episode (Mar 28), dennis said: > At 05:08 PM 3/27/98 -0600, you wrote: > >In the last episode (Mar 27), dennis said: > >> > >> Our servers run rather fast...is there a way to get them to read > >> the time from the bios (other than rebooting of course). > > > >Do you mean the clocks are running too fast for xntpd to keep accurate > >time? > > Why do I need to run "yet another deamon" on my servers when I have a > perfectly accurate clock in the machine? > > I suppose the answer is that you can't do it, correct? Well, the RTC only has a resolution of one second, doesn't it? So even though it may drift less than the CPU's internal clock, you probably don't want do be using it as your primary clock after the system comes up. Try adding the following options to your kernel; it looks like they try to calibrate some other timers against the RTC. With both options set, my machines are recording clock drifts of under 6 ppm (hourly clock adjustments of +/- 0.00005 sec according to xntpd). options "CLK_USE_I8254_CALIBRATION" options "CLK_USE_I586_CALIBRATION" If you don't want to run xntpd, you can always run ntpdate once an hour (or once a day) from cron. If you really wanted to, you could probably hack the kernel to watch for RTC clock updates (that occur once per second), and reset the kernel's clock to that. -Dan Nelson dnelson@emsphone.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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