[Bug 422858] Re: Atom N280 frequency scaling not supported

[rkagan]

On Wed, Nov 11, 2009 at 11:35:45PM -0000, Runar Ingebrigtsen wrote:
> "We have reached the conclusion that Intel's EIST power saving feature
> is the source of varying frequency for this model.

That's sorta telling the obvious.  The whole point of this feature is
to save power by varying the cpu clock rate.  E.g. on a mostly idle
system the clock sticks at its minimum, 800MHz.

The problem is not in the feature per se, but in the fact that the BIOS
reports the range of available frequencies smaller than the processor is
actually capable of.  As a result, the processor can't reach its maximum
speed when it's needed because the OS thinks that the maximum is lower.

Disabling the speed adjustment can be done by e.g. unloading the
acpi-cpufreq module (well, from your original post I conclude that this
may not be possible with Ubuntu kernel as it's apparently compiled in
the kernel).  However, you lose some of your on-battery time.

So consider their proposal as a temporary workaround, which I wouldn't
even apply myself becase I care more about the on-battery time than
about the max cpu speed.

A more likely reason for the problem is that their BIOS (InsydeH2O, as
in my Lenovo S10-2, right?) is older than the processor and doesn't
recognize its features, doing some defaults instead.  This would also
explain the other problem we both suffer from, the absense of NX bit
support (which BTW is a security feature).

-- 
Atom N280 frequency scaling not supported
https://bugs.launchpad.net/bugs/422858
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