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Cryptix_00

Member

Registered: 2008-07-16

Posts: 135

Different CPU reading on cpufreq

dual core processor normally runs at 2.20 GHz. it's on a thinkpad T61 so when it's not plugged in i like to set:

cpufreq-set -g ondemand. which is supposed to make both processors run at 0.8 GHz, then scale up accordingly.

but when i run it, it sets one proc at 0.8 and the other at 2.20. i didn't even know this was possible

output of cpufreq-info:

cpufrequtils 005: cpufreq-info (C) Dominik Brodowski 2004-2006
Report errors and bugs to cpufreq@vger.kernel.org, please.
analyzing CPU 0:
  driver: acpi-cpufreq
  CPUs which need to switch frequency at the same time: 0
  hardware limits: 800 MHz - 2.20 GHz
  available frequency steps: 2.20 GHz, 2.20 GHz, 1.60 GHz, 1.20 GHz, 800 MHz
  available cpufreq governors: powersave, ondemand, performance
  current policy: frequency should be within 800 MHz and 2.20 GHz.
                  The governor "ondemand" may decide which speed to use
                  within this range.
  current CPU frequency is 800 MHz.
analyzing CPU 1:
  driver: acpi-cpufreq
  CPUs which need to switch frequency at the same time: 1
  hardware limits: 800 MHz - 2.20 GHz
  available frequency steps: 2.20 GHz, 2.20 GHz, 1.60 GHz, 1.20 GHz, 800 MHz
  available cpufreq governors: powersave, ondemand, performance
  current policy: frequency should be within 800 MHz and 2.20 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency is 2.20 GHz.

Last edited by Cryptix_00 (2009-05-18 01:47:08)

bender02

Member

From: UK

Registered: 2007-02-04

Posts: 1,328

Re: Different CPU reading on cpufreq

You have to set if for both cores separately (see for instance how it is done in the "daemon" /etc/rc.d/cpufreq, which you can use to set the ondemand governor automatically at boot).
cpufreq -c 0 -g ondemand
cpufreq -c 1 -g ondemand

StaticPhilly

Member

From: UK

Registered: 2009-05-15

Posts: 53

Re: Different CPU reading on cpufreq

This could be wrong but its my understanding accross most distros,

On mobile devices (anything that uses a battry) then the system only uses what it needs, so if it dosnt need 2.20 GHz one second then it wont waste power doing so. If for example you start a game up it will then change it to what it needs say 2.20 GHz. Its purley a power-saving tweak. I personally have never had any problems nor noticed any diffrence in performance so i'd say this is a good thing.

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Lightweight software dose not mean less! It just means you have to get your finger out and make it do and look like you want!