HOWTO: Configure CPU scaling to decrease heat and increase battery life

[thebert]

Wow guys thanks for all of the replies. I wrote this months ago and totally forgot all about this thread and just found it again. If anyone has any improvements or suggestions I will be happy to add them.

[midnightray]

Thanks for guide worked great.

[lutra]

Wow guys thanks for all of the replies. I wrote this months ago and totally forgot all about this thread and just found it again. If anyone has any improvements or suggestions I will be happy to add them.

Hi All,
thanks for the guide!

I was noticing that on my core 2 duo processor laptop it is not possible to set different frequencies for the two cores. Is that normal?

PS
I'm not even sure that it can be somehow useful, just asking.

[Bad_Byte]

To op: Heres a simple script that allows one to select the modes without the manual hassle of cat <governor> /sys/.... for each core or without having to go overkill and use kpowersave. n00b scripting but it gets the job done =)

To lutra: yes, for C2D/Q all cores have to be set to the same governor to be in effect. Think the upcoming Phenoms from AMD will allow seperate core speeds.

Download link

#!/bin/bash
# cpu_speed.sh
# Last edit: 2008-02-28

if [ $1 = auto ] ; then MODE=ondemand
    elif [ $1 = max ] ; then MODE=performance
    elif [ $1 = min ] ; then MODE=powersave
    elif [ $1 = user ] ; then MODE=userspace
    elif [ $1 = laptop ] ; then MODE=conservative # Said to only work on laptop processors.
    else
        echo "No mode selected"
        exit
fi

CORES=$(ls /sys/devices/system/cpu | grep cpu | wc -l) # Outputs number of cores
let CORES=CORES-1 # Core adjustment for further use

COUNTER=0
while [ $COUNTER -le $CORES ]; do
    echo $MODE | sudo tee /sys/devices/system/cpu/cpu$COUNTER/cpufreq/scaling_governor > /dev/null 
    # Confused?. Tee reads std.out and writes that into file and std.out, that
    # part we don't need so the black hole /dev/null can eat that part
    echo Core $COUNTER mode: $MODE
    let COUNTER=COUNTER+1
done

[chochem]

For the XFCE4 people:

sudo apt-get install xfce4-cpu-freq-plugin xfce4-governor-plugin

and a thread:
http://ubuntuforums.org/showthread.php?t=516383

[beercz]

Great guide - thanks for this. Should now be able to extend my hp laptop's battery life a little bit more.

[GijsH]

After all the praise on this HowTo, a slightly more negative note: on my Feisty system (Sony Vaio) the very 1st command fails with:

gijs@gijs:~$ ls /sys/devices/system/cpu/cpu0/cpufreq
ls: /sys/devices/system/cpu/cpu0/cpufreq: No such file or directory


Now what I do to reduce the heat my laptop is emitting?

[handsomeDave]

After all the praise on this HowTo, a slightly more negative note: on my Feisty system (Sony Vaio) the very 1st command fails with:

gijs@gijs:~$ ls /sys/devices/system/cpu/cpu0/cpufreq
ls: /sys/devices/system/cpu/cpu0/cpufreq: No such file or directory

I get that too

I've got a Pentium M 1.6Ghz

[albasheers]

anybody please help me

i have changed the setting to performance ,
and when just restarted my laptop its unable to start
its making teet teet sound and then no display

my laptop is hp dv2000 and its configuration is

intel core 2 duo 1.83 ghz

1gm ram and 128 mb nvidia graphic card

[InfinityCircuit]

Sorry to break it to you, but ondemand is superior to conservative on intel chipsets. Intel's own kernel developer explains why:

http://www.bughost.org/pipermail/pow...ay/000166.html
http://www.bughost.org/pipermail/pow...ay/000073.html
http://www.bughost.org/pipermail/pow...ay/000071.html

The basic idea is this: Since you always have to keep the northbridge running, power usages scale slower than cpu speed increases. This means it is faster to jump to the highest speed and then back down to idle, because it takes longer to perform the same operations at a slower speed.