Date: Sun, 21 Feb 1999 14:56:40 -0800 From: "Dan O'Connor" <dan@jgl.reno.nv.us> To: "freebsd-questions" <freebsd-questions@freebsd.org> Subject: Q: Timecounter "TSC" and drifting clock and calcru neg time Message-ID: <01f501be5ded$7278bc20$0200000a@danco.home>
next in thread | raw e-mail | index | archive | help
Good Sunday, everyone,
I'm running 3.1-STABLE on a Pentium 90 machine.
I have a clock that drifts badly (fast by almost 2 min per hour), although
after some reboots, it drifts just a few seconds per hour. Occasionally
after a reboot, I'll get 'calcru negative time' messages.
I've traced this problem to the following symptom: During boot, the line
Timecounter "TSC" frequency xxxxxxxxx Hz
is displayed. The routine that clocks the system seems more like a random
number generator, and I've seen the following values:
90.2 MHz
87.7 MHz
77.5 MHz
At 90.2 MHz, the system clock is pretty accurate.
At 87.7 MHz, the clock runs fast by over 90 seconds per hour.
(And 90MHz / 87.7 MHz * 3600 - 3600 = +94 seconds per hour, imagine that!)
At 77.5 MHz, the 'calcru negative time' errors pop up.
I know that, as reported on this list, the timekeeping code is broken, but
my question is this:
Is there somewhere I can tell the system to use a TSC frequency of 90000000
Hz and have it skip it's internal calibration? I don't envision changing
CPUs too often, so I'm not worried about hardcoding it...
--Dan
** The thing I like most about Windows 98 is...
** You can download FreeBSD with it!
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?01f501be5ded$7278bc20$0200000a>