Re: Dual-core system will not create NTP peers
I have discovered the source of the problem: the file
/etc/default/adjtimex had a TICK value of 9750. That's 2.5% less than
the standard value of 10000 and accounts exactly for the clock skew I
observed.
I adjusted the tick back to a reasonable value (see below) and my clock
problems appear to be solved.
I have no idea how the file obtained this value. I suspect that when
adjtimex was installed, the package used /usr/sbin/adjtimexconfig and
that it somehow obtained completely incorrect values.
To adjust tick and frequency for maximum accuracy, I highly recommend
Larry Dolittle's ntpclient package at
<http://doolittle.icarus.com/ntpclient/>. In particular, the HOWTO file
not only explains the debug output of his tools but also gave me
invaluable information that I could use to resolve my own problem.
Math notes to future readers, since "tick" can be confusing: the tick is
"how many microseconds to add to the current clock reading." Ticks occur
100 times per what the system thinks is a second, and if the value of a
tick is set to 10000, then it will add 100 * 10,000 = 1,000,000
microseconds to the system clock each second. Because the value of the
tick in my system was set to 9750, each second I added only 975,000
microseconds to the system clock, for a deficit of 2.5%. See the
adjustimex man page as well as Larry's HOWTO page.
--
Moshe Yudkowsky * moshe@pobox.com * www.pobox.com/~moshe
"Only a fool fights in a burning house."
-- Ancient Klingon Proverb
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