Re: System clock frequency offset changes drastically across reboots

[John Sigler <linux.kernel@free.fr>]

[ Expanding recipients list to include NTP mailing list ]

> John Sigler wrote:
>
> > I'm using 2.6.20.7-rt8 on a P3.
>
> (But some ntpd users have reported the problem with mainline kernels and 
> different versions.)
>
> > I've noticed that the frequency offset of my system clock (computed 
> > either by ntpd, or by hand) changes drastically across reboots.
> >
> > By drastically, I mean +/- 60 ppm every time I reboot.
> >
> > Apparently this is caused by some imprecision in the frequency 
> > estimation done in calculate_cpu_khz() (arch/i386/kernel/tsc.c)
> >
> > My brutally crude work-around was to skip the computation altogether 
> > and hard-code the "correct" value for cpu_khz.
> >
> > http://linux.kernel.free.fr/cpu_khz.adlink
> >
> > Has this issue been investigated more thoroughly by other users?

Is there, perhaps, more appropriate a forum to discuss such matters?

Regards.

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