Date: Fri, 4 Jun 1999 12:30:03 -0700 (PDT) From: Chris Dillon <cdillon@wolves.k12.mo.us> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/12022: System clock timewarps Message-ID: <199906041930.MAA79278@freefall.freebsd.org>
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The following reply was made to PR kern/12022; it has been noted by GNATS.
From: Chris Dillon <cdillon@wolves.k12.mo.us>
To: dwhite@pond.net
Cc: freebsd-gnats-submit@FreeBSD.ORG
Subject: Re: kern/12022: System clock timewarps
Date: Fri, 4 Jun 1999 14:20:11 -0500 (CDT)
On Fri, 4 Jun 1999 dwhite@pond.net wrote:
> I've also tried setting kern.timecounter.method=1 with no effect.
> >How-To-Repeat:
> . Find a PC.
> . Boot 3.1 or later on it a few times.
> . Watch the TSC go nuts.
> >Fix:
On the one 3.1+ (actually 3.2-STABLE) PIII-500 box I have here at
work, TSC is extremely stable. Over 30 boots, I see it has ranged
from 498830507 Hz to 498831075 Hz. I assume a total deviation of less
than 1KHz (actually 568Hz, .000001% deviation) on a 500MHz clock is
pretty darn stable. (Almost too stable... did I get that percentage
right? I'm no statistician).
I did experience just one time on my box at home a serious deviation,
but overall it seems to be very stable. I don't have the actual
figures from my box at home available right now, but ntpdate never
adjusted the time more than about a couple of seconds a day until that
one time the reported TSC was about 50% of the actual clockrate
(Celeron 433), making the wall clock run extremely fast.
-- Chris Dillon - cdillon@wolves.k12.mo.us - cdillon@inter-linc.net
FreeBSD: The fastest and most stable server OS on the planet.
For Intel x86 and Alpha architectures (SPARC under development).
( http://www.freebsd.org )
"One should admire Windows users. It takes a great deal of
courage to trust Windows with your data."
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