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Date:      Tue, 20 Jul 1999 15:08:08 -0700
From:      "David Schwartz" <davids@webmaster.com>
To:        <stable@freebsd.org>
Subject:   Tuning the system's clock
Message-ID:  <000001bed2fc$593b6990$021d85d1@youwant.to>

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	FreeBSD's internal high-precision clock seems to be based on the
processor's instruction cycle counter. I've found that on one machine, the
clock is about 150 ppm fast. So I tried to reduce the machdep.tsc_freq
value. That was bad -- instant reboot.

	Is there a better way of adjusting that value? Changing 'tick' doesn't seem
to do much.

	Are the NTP pll values for mult/div documented anywhere? It seems to divide
before it multiplies, which means that using them for small offsets would
require high divisors, and hence a loss of accuracy.

	David Schwartz
	http://www.gpsclock.com/



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