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Date: Thu, 19 Oct 1995 22:51:40 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199510191251.WAA16201@godzilla.zeta.org.au>
To: freebsd-current@FreeBSD.ORG, jhay@mikom.csir.co.za
Subject: Re: clock running faster?
Sender: owner-current@FreeBSD.ORG
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>Yesterday I rebooted my current machine (90M Pentium) with a new kernel. The
>previous kernel was build on the 13th. Now suddenly the clock gains almost
>30 second in an hour. Previously the clock was very stable. I have even
>rebooted and it still does it.

>Has anybody seen something like this? I see there were changes made to
>i386/isa/clock.c and kern/kern_clock.c.

The changes have the effect of making the Pentium clock the reference.
Apparently your 8254 clock's frequency is closer to its nominal value
(1193182 Hz) than your Pentium clock's frequency is to its measured
value (pentium_mhz = N MHz where N is as reported at boot time).  The
measurement and use of N depends on N being an integer for accuracy.
Apparently the measured value is too small by a factor of 90/90.75.

Bruce