[ltp] kernel detecting incorrect processor speed

[Paul Hahn]

Lai Zit Seng wrote:

> On Fri, 8 Sep 2000, dan kelley wrote:
>
> > I've just installed mandrake 7.1 on a new T20 (pIII 700).  install went
> > fine, just needed to replace the X server with a S3 Savage compatible
> > version.  the machine shipped with 1 128 meg chip, i added a 256 meg chip
> > to that.  oddly, the machine seemed slow, so i checked out /proc/cpuinfo:
> >
> > cpu MHz       :       145.076181
> > bogomips      :       311.30
> >
> > i've rebooted the machine several times, and it usually comes up with these
> > same values.  once or twice, it has come up with 586 MHz.
> >
> > anyone heard of anything like this happening?
>
> Yes, it seems to be happening to my T20 all the time. The number ranges
> from 147MHz, 148MHz, 284MHz, 293MHz, 530MHz, 547MHz etc... All this while
> booting on battery power.
>
> Anyone has any ideas why this is so?
>
> Regards,
>
> .lzs

Yes. This is so because of the IBM bios. You can control the speed of all
laptops, and thus their power consumption, by using the Fn+F9 key, or whatever
the water spigot character is over on your T20. This value is only determined
once in Linux, at boot up when bogomips is run. So if you change it after you
boot, or plug the power cable back in (which automatically speeds up your
proc) you will have to reboot inorder to "see" the change. The proccessor is
running faster however, you will just not be able to see the change on your
utilities because they use bogomips to determine this value, and since it only
runs once will not report the change. In Winblows you can use the Ibm utilities
to control the default values for whether or not your notebook slows down when
on battery or not. Forcing to stay on full flow will solve the "problem" of it
going slower on battery. This is a issue on all IBM laptops, not just speed
step, although it may compound the confusion.

Hoped that helped.

JollyEugene

>
>
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