dmesg showing wrong frequency (IBM T30)

[Poul-Henning Kamp]

In message <20030718141239.GB19817 at speedy.unibe.ch>, Tobias Roth writes:
>Hi
>
>On my IBM T30 1.8GHz, dmesg (with both 4.8 and 5.1) shows me this line:
>
>CPU: Intel(R) Pentium(R) 4 Mobile CPU 1.8GHz (1196.13-MHz 686-class CPU)
>
>Various windows utilities also claim that the cpu identification string
>marks my cpu as 1.8 GHz unit, while the maximum frequency always gets
>detected as something just below 1.2GHz.
>
>What is wrong here? To other IBM T30 users: Is your CPU identification
>correct?

What's "wrong" here is that the BIOS/ACPI firmware in your laptop
runs your CPU at a reduced rate in order to make the battery last
longer.

Manufactureres have taken great care to not make it clear that the
specs they give you are all reachable, _just_not_at_the_same_time_.

You may be able to twiddle things in the BIOS or using ACPI and
get faster CPU but less battery lifetime.

It can also be that the case that the "cooling solution" (ie: fans,
fins etc) does not work well enough and the ACPI code has slowed
down the CPU in order to not melt anything [*].

In particular our ACPI code does not seem to always start fans when
they should due to high temperatures.

Poul-Henning

[*] Known in certain circles as a "Warnering your laptop" :-)

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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Never attribute to malice what can adequately be explained by incompetence.