HowTo: Undervolt your notebook CPU for longer battery life

[excogitation]

Ok guys,

... give me step by step instructions.

Derived from the first post:

Step by step:

1. This howto depends on the kernel module acpi-cpufreq to control your cpu. To find out if you're using it try

lsmod | grep acpi_cpufreq

You should see sth. like this:

acpi_cpufreq           14892  2 
freq_table              5536  3 acpi_cpufreq,cpufreq_stats,cpufreq_ondemand
processor              36872  4 acpi_cpufreq,thermal

In case you don't see anything, you don't use acpi-cpufreq, but maybe the speedstep.centrino module.
Then this howto is not for you ...

2. You need to get a modified version of your acpi_cpufreq module, one with PHC support build in. PHC means processor hardware control and is the magic that makes it going. There are several ways to get this module.

... the precompiled modules I offer below are 32bit only.
It has to match your kernel. If there isn't the right one compile it yourself or wait for someone to provide it to the community.

3. There are right now versions for kernel 2.6.24-16-generic, 2.6.24-17-generic, 2.6.24-18-generic and 2.6.24-19-generic. To find out what kernel you have open a terminal and type:

uname -r

So once you know, download the right kernel module for 2.6.24-16-generic or 2.6.24-17-generic or 2.6.24-18-generic or 2.6.24-19-generic.
4. First backup your old module.

sudo cp /lib/modules/`uname -r`/kernel/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.ko /lib/modules/`uname -r`/kernel/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.ko.old

(basically copies it to a new name)



5. Then copy the downloaded file to the right place:

sudo cp acpi-cpufreq.ko /lib/modules/$(uname -r)/kernel/arch/x86/kernel/cpu/cpufreq

[/INDENT]

5. Reboot. If the module is installed correctly,

cat /sys/devices/system/cpu/cpu0/cpufreq/phc_controls

should give you sth like this:

12:38 10:30 8:24 6:18

The value before the : stands for the frequency, the later for the voltage.
[B]

I'd get the PHC tool to start tweaking after that.

[M4rotku]

At the line:

cat /sys/devices/system/cpu/cpu0/cpufreq/phc_controls

Is where I have the problem. Instead of four outputs, I only get two:

joey@joey-laptop:~$ cat /sys/devices/system/cpu/cpu0/cpufreq/phc_controls
9:43 6:19

I think that this is where the problem is coming from and I have no idea how to go about fixing it. I have not heard of anyone else having this problem and so I'm starting to wonder what's going wrong.

Can anyone tell me why I'm only getting 2 outputs and how I would go about adjusting the process because of this?

Much thanks,
M4rotku

[jocko]

At the line:



Is where I have the problem. Instead of four outputs, I only get two:



I think that this is where the problem is coming from and I have no idea how to go about fixing it. I have not heard of anyone else having this problem and so I'm starting to wonder what's going wrong.

Can anyone tell me why I'm only getting 2 outputs and how I would go about adjusting the process because of this?

Much thanks,
M4rotku

I don't think you need to adjust anything because of this.
How many "outputs" you get is built in to your cpu, there's no way you can change that. If the cpu can only be set to two different frequencies, you only get two outputs...

Exactly what is your problem? At which step does the howto fail, and what is the command line output from that step?

[M4rotku]

Ok jocko,

I got to the point at which I got confused. In the step in which the script is run, I get confused about how to do it with dual core.

Do I enter "burnMMX" in the same terminal in which I am running the script, or in a different terminal?

Much thanks,
M4rotku

[jocko]

Ok jocko,

I got to the point at which I got confused. In the step in which the script is run, I get confused about how to do it with dual core.

Do I enter "burnMMX" in the same terminal in which I am running the script, or in a different terminal?

Much thanks,
M4rotku

Either you run:

burnMMX &

before you start the script in the same terminal, or you run it in a different terminal after you have started the script. Doesn't really matter, as long as you have two burnMMX processes running (one started manually and one started by the script), both cores will be used.

But a little warning on using/trusting the script:
On some cpus it doesn't apply the settings to both cores (it doesn't on mine) and it also doesn't manage to keep control of the cpu frequency governor (mine gets reset to "ondemand" directly after the script claims it has succesfully set a lower frequency), so the script only tests the highest frequency and when it thinks it tests lower frequencies, the cpu still runs full speed...

[M4rotku]

Ok, I think I ran the script correctly and this was the eventual output:

Default VIDs: 43 19
Current VIDs: 0 19
Testing VID: 0 (700 mV)
..............................
Default VIDs: 43 19
Current VIDs: -1 19
Testing VID: -1 (684 mV)
./linux-phc-optimize.bash: line 161: printf: -1: invalid option
printf: usage: printf [-v var] format [arguments]


The lowest acceptable VID is 0.

Recovering CPU.

Run this script again to continue the optimization.
./linux-phc-optimize.bash: line 138: 8816 Terminated burnMMX
[1]+ Terminated burnMMX (wd: ~)
(wd now: ~/Desktop)

Then, when I tried to run the script again, I got this result:

joey@joey-laptop:~/Desktop$ sudo /.linux-phc-optimize.bash
sudo: /.linux-phc-optimize.bash: command not found

Then, I ls'ed to see if it was there and it was:

joey@joey-laptop:~/Desktop$ ls
acpi-cpufreq.ko functions.bash linux-phc-optimize.bash phc_cur_pos phc_tweaked_vids

What am I doing wrong? It didn't crash and I couldn't run the script again as it told me to.

[jocko]

joey@joey-laptop:~/Desktop$ sudo /.linux-phc-optimize.bash

sudo: /.linux-phc-optimize.bash: command not found

it should be:

sudo ./linux-phc-optimize.bash

Note that the point is before the slash, not after (which means "run the file "linux-phc-optimize.bash" which is in the current (./) directory", the way you wrote it it means "run the file ".linux-phc-optimize.bash" which is (hidden) in the root (/) directory", and as that file does not exist you get a command not found error).

[M4rotku]

I swear this script hates me. How does it know that it's me when I run it. Ok, here's the problem this time.

When I tried to run the script for the second time, I recieved the following error starting from where it would install cpuburn:

Install required packages.
Will use burnMMX (part of cpuburn package) to stress CPU.
Install: cpuburn
> SKIPPED: Already installed


Will use current directory to store/retrieve test results.

Read phc_default_vids:
> Success!

Load VIDs from 'phc_tweaked_vids'
> ERROR: Wrong VID count!
joey@joey-laptop:~/Desktop/Undervolt$

and then the script quits and I end up back where i started in my Undervolt folder. grr.

I think this is where I finally gave up the last time. I want to keep going though, so if anyone can tell me what to do, then I'll do it.

Much thanks,
M4rotku

[aldeby]

try deleting these files in your home directory (or in /root one if you are running the script from recovery console)

phc_cur_pos
phc_tweaked_vids

then run the script again.

as for burnMMX simply run

burnMMX &

in the terminal before running the script,
this way you are going to stress both cores of your dual core CPU.

cheers!

[M4rotku]

Don't I need those scripts to run it the second time so that the main script will know where it left off the last time?