[ntp:hackers] Bug in frequency calculations?
Hal Murray
hmurray at megapathdsl.net
Wed Jan 30 16:11:44 UTC 2008
There is a bug in the TSC calibration routine in the Linux 2.6 kernel.
Run
grep Det /var/log/messages | grep MHz
You will probably find things like this
Jan 25 10:10:00 shuksan kernel: Detected 2793.049 MHz processor.
Jan 25 22:45:41 shuksan kernel: Detected 2793.112 MHz processor.
Jan 25 22:47:44 shuksan kernel: Detected 2793.051 MHz processor.
Jan 25 22:49:34 shuksan kernel: Detected 2793.050 MHz processor.
Jan 25 22:51:07 shuksan kernel: Detected 2793.147 MHz processor.
That's basically jerking the drift file around. It takes ntpd a while to recover, maybe a half day for big jumps.
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