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Thread: HowTo: Undervolt your notebook CPU for longer battery life

  1. #481
    Join Date
    Sep 2008
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    20
    Distro
    Ubuntu 9.10 Karmic Koala

    Exclamation Re: HowTo: Undervolt your notebook CPU for longer battery life

    :guitar
    LOOK here
    http://openmindedbrain.info/09/05/20...-04-lucid-lts/

    Instructions copied below....
    1. As we are going to use a custom kernel, we need to add the linux-phc PPA repository, so just open a terminal and execute:

    1 $ sudo add-apt-repository ppa:linux-phc/ppa
    2 $ sudo apt-get update
    Basically they provide the same kernel as the Ubuntu one but with the patch that is capable for Undervolting.
    2. Next we need to install the phc kernel, with headers:

    1 $ sudo apt-get install linux-generic-phc linux-headers-generic-phc
    Ok, now we need to restart and use the installed phc kernel when booting. After restarting, you can check if you are using the phc kernel by using

    1 $ uname -r
    2 2.6.32-21-generic-phc
    If no "phc" appears, then you have to configure grub2 to allow you to chose boot options and select the phc kernel at boot time. This can be done many ways one would be:
    (This section was NOT necessary for me.... zcats)

    1 sudo update-grub
    and count the number of lines that says "Found linux image" (first one is 0) and, when you found the phc one, do:

    1 sudo gedit /etc/default/grub
    then just change the "GRUB_DEFAULT=0" to the number of the entry you found that has phc. Save the file and do a update-grub command again like in the first step. Now you can reboot into the phc kernel.
    3. Great, we are using a phc kernel, now we need to add the actual undervolt module, as the kernel comes only with support for it, not the actual module. First download phc-intel offtree module from here. Right now they have "phc-intel-0.3.2-10 offtree" version. Direct link to the tar.bz2 file here. Unpack the files anywhere and point the terminal to the directory where you extracted the files and do:

    1 $ make prepare
    2 $ make
    3 $ sudo make install
    Right now you should have the module installed, check if everything worked by typing:

    1 $ cat /sys/devices/system/cpu/cpu0/cpufreq/phc_default_vids
    2 40 34 31 27 23 15
    If everything worked, you should see some numbers (the ones above are the default ones for my CPU). If not, you may try to restart and check back to see if it works.
    4. So right now we are set, the only thing we have to do is... undervolt the CPU.
    Now we have to discover the limits of the CPU by lowering it's current voltage one step at a time and set the voltage 4 steps above the critical limit (where the cpu starts to give wrong calculations or the PC simply crashes).

    Why four? Well the recommendation was 2 steps above, but with this limit the PC crashed in the same day hours later, so I made it 3 steps, then some days after it crashed again. So I think 4 steps should actually do it. If not, you may increase this value until it suits you.

    Ok great now how to find the actual critical limit? There exists a script, created by the community, but it's old and it does not work for multi core CPU's and also in my particular case it sets the voltage directly below this critical limit so the PC crashes instantly.

    I updated this script and made it work on multi core CPU's (hopefully it will work for you too), so you just have to download the script, then give it execution permissions and execute it and follow on-screen indications see http://openmindedbrain.info/wp-conte...ndervolt.bash:

    1 $ chmod +x intel-phc-undervolt.bash
    2 $ ./intel-phc-undervolt.bash
    Oh and make sure you close as many applications as possible when executing the script as the system may actually turn instable (it is intended actually) just to prevent any data loss. The script treats all CPU's cores with the same voltages, so if one of them is weaker than the other (does not support such a aggressive undervolting) is this the critical value that the script uses for all of the others, even if they could possibly use a even lower value.
    5. After you finished with the script, now you should have a "phc_tweaked_vids" file, containing the acceptable steps for your CPU. Now you only have to make changes permanent (load them at every boot of the pc) by editing /etc/rc.local file:

    1 $ sudo gedit /etc/rc.local
    and adding one entry for every core you have, something like:

    1 echo "23 20 4 4 4 4" > /sys/devices/system/cpu/cpu0/cpufreq/phc_vids
    2 echo "23 20 4 4 4 4" > /sys/devices/system/cpu/cpu1/cpufreq/phc_vids

    just before the "exit 0". Note that "23 20 4 4 4 4" are my values, you have to replace the above with your values, that came from the "phc_tweaked_vids" file. So that's about it. Not too easy, not too complicated.

    So... is it worth it? I have done some tests to see if the above actually works as said, so first I tested to see if on battery using powertop application and the CPU temperature I could see any differences. None actually, if the CPU is in idle state, there is no actual gain using undervolting, be it battery or temperature.

    But when I've done the test under full load (using 2 burnMMX instances, one for every core) and with the CPU set at it's maximum 2.4Ghz I could see a very very noticeable difference.

    see website for data of temp and energy (W) saved
    Last edited by zcats; June 1st, 2010 at 08:14 PM.

  2. #482
    Join Date
    Nov 2009
    Beans
    13

    Re: HowTo: Undervolt your notebook CPU for longer battery life

    Please, who can tell me, what is wrong?
    Code:
    vladimir@vladimir-laptop:~/Downloads/phc-intel-0.3.2-10$ make prepare
    FOUND AVAILABLE PATCHSET. PREPARING.
    patching file phc-intel.c
    vladimir@vladimir-laptop:~/Downloads/phc-intel-0.3.2-10$ make
    make -C /lib/modules/`uname -r`/build SUBDIRS=/home/vladimir/Downloads/phc-intel-0.3.2-10 modules
    make[1]: Entering directory `/usr/src/linux-headers-2.6.32-22-generic-phc'
      CC [M]  /home/vladimir/Downloads/phc-intel-0.3.2-10/phc-intel.o
      Building modules, stage 2.
      MODPOST 1 modules
      CC      /home/vladimir/Downloads/phc-intel-0.3.2-10/phc-intel.mod.o
      LD [M]  /home/vladimir/Downloads/phc-intel-0.3.2-10/phc-intel.ko
    make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-22-generic-phc'
    vladimir@vladimir-laptop:~/Downloads/phc-intel-0.3.2-10$ sudo make install
    install -m 644 -o root -g root phc-intel.modprobe /etc/modprobe.d/phc-intel.conf
    mkdir -p /lib/modules/2.6.32.11+drm33.2/extra
    install -m 644 -o root -g root phc-intel.ko /lib/modules/2.6.32.11+drm33.2/extra/
    depmod 2.6.32.11+drm33.2 -a
    vladimir@vladimir-laptop:~/Downloads/phc-intel-0.3.2-10$ cat /sys/devices/system/cpu/cpu0/cpufreq/phc_default_vids
    cat: /sys/devices/system/cpu/cpu0/cpufreq/phc_default_vids: No such file or directory
    vladimir@vladimir-laptop:~/Downloads/phc-intel-0.3.2-10$
    Ubuntu 10.04. My CPU is Core2Duo T5600 (Mobile) And i used manual in previous post by zcats(#481)

    Thank You!
    Last edited by Vladimir_S; June 28th, 2010 at 03:42 PM.

  3. #483
    Join Date
    May 2008
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    62

    Re: HowTo: Undervolt your notebook CPU for longer battery life

    I am having the same problem that Vladimir_S. I am using a Core 2 Duo T5550 laptop on Ubuntu 10.4 amd64.

    Any ideas??

  4. #484
    Join Date
    Nov 2005
    Location
    Uppsala, Sweden
    Beans
    2,181
    Distro
    Ubuntu 12.10 Quantal Quetzal

    Re: HowTo: Undervolt your notebook CPU for longer battery life

    Quote Originally Posted by Vladimir_S View Post
    Please, who can tell me, what is wrong?
    Code:
    vladimir@vladimir-laptop:~/Downloads/phc-intel-0.3.2-10$ make prepare
    FOUND AVAILABLE PATCHSET. PREPARING.
    patching file phc-intel.c
    vladimir@vladimir-laptop:~/Downloads/phc-intel-0.3.2-10$ make
    make -C /lib/modules/`uname -r`/build SUBDIRS=/home/vladimir/Downloads/phc-intel-0.3.2-10 modules
    make[1]: Entering directory `/usr/src/linux-headers-2.6.32-22-generic-phc'
      CC [M]  /home/vladimir/Downloads/phc-intel-0.3.2-10/phc-intel.o
      Building modules, stage 2.
      MODPOST 1 modules
      CC      /home/vladimir/Downloads/phc-intel-0.3.2-10/phc-intel.mod.o
      LD [M]  /home/vladimir/Downloads/phc-intel-0.3.2-10/phc-intel.ko
    make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-22-generic-phc'
    vladimir@vladimir-laptop:~/Downloads/phc-intel-0.3.2-10$ sudo make install
    install -m 644 -o root -g root phc-intel.modprobe /etc/modprobe.d/phc-intel.conf
    mkdir -p /lib/modules/2.6.32.11+drm33.2/extra
    install -m 644 -o root -g root phc-intel.ko /lib/modules/2.6.32.11+drm33.2/extra/
    depmod 2.6.32.11+drm33.2 -a
    vladimir@vladimir-laptop:~/Downloads/phc-intel-0.3.2-10$ cat /sys/devices/system/cpu/cpu0/cpufreq/phc_default_vids
    cat: /sys/devices/system/cpu/cpu0/cpufreq/phc_default_vids: No such file or directory
    vladimir@vladimir-laptop:~/Downloads/phc-intel-0.3.2-10$
    Ubuntu 10.04. My CPU is Core2Duo T5600 (Mobile) And i used manual in previous post by zcats(#481)

    Thank You!
    Quote Originally Posted by nicocarbone View Post
    I am having the same problem that Vladimir_S. I am using a Core 2 Duo T5550 laptop on Ubuntu 10.4 amd64.

    Any ideas??
    You need to reboot.

  5. #485
    Join Date
    May 2008
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    62

    Re: HowTo: Undervolt your notebook CPU for longer battery life

    The problem cannot be solved by rebooting (is the first thing I tried), but I found the solution.

    The problem is related to a bug in the phc modified kernel 2.6.32-24-generic-pch. The file utsrelease.h, located in "/usr/src/linux-headers-2.6.32-24-generic-phc/include/linux" is used by the install script oh the intel-phc module to locate the kernel in use, but the string UTS_RELEASE is badly defined (http://www.linux-phc.org/forum/viewtopic.php?f=9&t=211) Where it says "2.6.32.15+drm33.5", it should say "2.6.32-24-generic-phc".

    Changing this line, and the repeating the install process, I could load the intel-phc module and I successfully undervolted my CPU. Now it uses 10w less under load and the temperatures are around 10-15C lower.

  6. #486
    Join Date
    May 2008
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    62

    Re: HowTo: Undervolt your notebook CPU for longer battery life

    Another question: Will it be necessary to repeat all the installation/undervolt process every time Ubuntu releases a new kernel?

    Sorry If this was explained before, I couldn't read the 49 pages.

  7. #487
    Join Date
    May 2008
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    62

    Re: HowTo: Undervolt your notebook CPU for longer battery life

    Me again, with another question:
    Everytime I suspend/resume the laptop, the volts are restored to defaults (at least I think this is what happens, because the watts used under load increase after a suspend/resume cycle). Is there a way to avoid this?

    Thanks

  8. #488
    Join Date
    Dec 2009
    Beans
    25

    Re: HowTo: Undervolt your notebook CPU for longer battery life

    I'm Running:-

    Toshiba q505 888

    Ubuntu 10.04 lucid 64Bit

    Core 7i q740
    Nvidia Gts 360m 1gb
    4 Gb Ram


    I Updated to 256.35 = Excellent / perfect

    Then my updates from X-swat and Xorg Egders updated to 256.44 this = my world falling apart.

    My system completely locks up / hags / kills its self within 4 mins of logging in.

    If I load anything I.E wine to run a game.

    It really doesnt like that... My problem is i'm only a year into ubuntu and I have done manual updates before, but what im doing isnt working as I have tried purge remove nvidia .44 and disabling the two ppa's then manually installing .35 ..

    BUT

    when I start the gdm = great it works, then when I restart = not great....because I'm on failsafe graphics and the x sever setting not in menu (if it is in menu then theres nothing in there; apart from that msg to restart X) and when I load Hardware drivers the nvidia card isnt there..

    I would like to think that some of your reading this are laughing because you are what I would call a pro in the ubuntu area and that you could / will post a detailed step by step to help me install .35 through the x-swat or x-org egder ppa or even manually download it and install it that way, so when I restart it works, and more to the point I can keep those two ppa's in my system so when i hit the update button I can see ubuntu wants to update to .44 which I WONT DO....

    One year into ubuntu and I haven't logged into windows since.

    As I find theres always someone will to help fix something in ubuntu..

    anyway thats that, Mr/Mrs pro.... can you post that guide please.

    P.S im currently on Linux-x86_64 NVIDIA Driver Version: 195.36.24 Server Version Number: 11.0 and Server Vendor Version: 1.8.2 NV-CONTROL Version: 1.22
    gnome 2.30.2 and kernel linux 2.6.32-24 generic
    platform X86_64



    Thanks
    Last edited by phazixc; August 4th, 2010 at 01:52 PM.

  9. #489
    Join Date
    May 2008
    Beans
    62

    Re: HowTo: Undervolt your notebook CPU for longer battery life

    phazixc:

    I would like to help you, but I have no experience in Nvidia drivers under Ubuntu. I would suggest you to purge the ppa, but you already did this, so I am out of ideas.

    What I suggest you is to open a new thread posting you problem, because it is completely off-topic here. Posting a new topic (in Absolute Beginner Talk, or maybe one of the Main Support Categories, like Multimedia and Video) will surely make it viewable to more people, and I am sure someone with the required experience in Nvidia drivers will help you.

  10. #490
    Join Date
    Dec 2009
    Beans
    25

    Re: HowTo: Undervolt your notebook CPU for longer battery life

    yeap no problem, i thought i posted this in a different form, sorry and thanks anyway.

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