Re: Time of day clock runs at twice the speed on (old) laptop

[Magnus Eriksson <magetoo%fastmail.fm@localhost>]

On Mon, 24 Nov 2008, Jared D. McNeill wrote:

> > Hi Magnus --
> >
> > If you run the following command as root:
> >
> >   # sysctl -w kern.timecounter.hardware=i8254
> >
> > Does the problem go away?

Yup:

# date ; sleep 10 ; date
Mon Nov 24 14:41:07 CET 2008
Mon Nov 24 14:41:27 CET 2008
# sysctl -w kern.timecounter.hardware=i8254
kern.timecounter.hardware: ACPI-Safe -> i8254
# date ; sleep 10 ; date
Mon Nov 24 14:42:05 CET 2008
Mon Nov 24 14:42:15 CET 2008
#

Everything else seems to work as well.  What are the relevant options if I 
want to make this permanent in a custom kernel?  (short of disabling ACPI 
entirely)


On Mon, 24 Nov 2008, Andrew Doran wrote:

> FWIW, x86 timer calibration is unreliable in 4.0. It's fixed in -current,
> which may matter here.

I'll try a recent snapshot and get back to you with the results.  I 
realize that there is probably something wrong with the hardware here, but 
at least it might be interesting to know how the kernel would handle that 
case (I guess).


MAgnus