Mailinglist Archive: opensuse-kernel (69 mails)

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Re: [opensuse-kernel] kernel & BIOS report (incorrectly?) different current/available speeds for overclocked CPU
  • From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
  • Date: Mon, 03 Aug 2009 08:34:05 +0100
  • Message-id: <4A76AF0D020000780000DA00@xxxxxxxxxxxxxxxxxx>
PGNet Dev <pgnet.dev+oskrn@xxxxxxxxx> 02.08.09 20:27 >>>
i've built up a new openSUSE server on a

mobo: ASUS M3A78-CM, BIOS r1903
cpu: AMD 2.8GHz Phenom II X4 920 (Black)

@ BIOS, i've overclocked the CPU by 33% from 2.8Hz -> 1.33 x 2.*8 = 3.7GHz.

booting to OS, the reported(/available) CPU freq is NOT that which the
BIOS reports.

questions:

(1) is this a bug, or expected behavior for OC'ing?
(2) if a bug, is it in kernel, or BIOS?

BIOS: Both this

available frequency steps: 2.80 GHz, 2.10 GHz, 1.60 GHz, 800 MHz

and (presumably, as you didn't show it) /var/log/messages would confirm
this. The identifiers for the corresponding frequencies are stored in ACPI
tables and/or MSRs, so if the BIOS "supported" overclocking, it would have
to update these tables/registers (the actual frequencies get calculated
from these identifiers).

The value /proc/cpuinfo reports is simply one of the frequencies reported
as available.

Jan

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