[ntp:hackers] Bug in frequency calculations?
Danny Mayer
mayer at ntp.isc.org
Thu Jan 31 13:47:50 UTC 2008
Hal Murray wrote:
> 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.
That's probably also affecting Bill Unruh's experiments.
Danny
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