Undervolting the Atom for less heat, more battery life.

Discussion in 'Linux' started by hardran3, Sep 13, 2008.

  1. hardran3

    hardran3

    Joined:
    Aug 11, 2008
    Messages:
    73
    Likes Received:
    0
    Location:
    Swift Current, SK, Canada
    I am running Ubuntu 8.04.1 and using the acerfand script, and it works great. I have also played around with undervolting and after some testing it makes a difference to heat and power usage, at high CPU usage anyway.

    I tested with burnMMX, running 2 instances to max out the CPU. Powertop to check power use, and the acerfand script to check tempurature.I have my fan set to kick in at 65 degrees, and turn off at 55.

    Without undervolting tested temp and power usage with powertop.

    Power = 12.4 watts avg over 5 minutes
    Temp ranged between 65 - 68 degrees, even after the fan kicked in.

    After I undervolted, things got better.

    When set to 12:24 10:17 8:10 6:3
    Power = 11.3 watts avg over 5 minutes
    Temp ramped up to 65, but after the fan kicked in it drops down to 61 - 63 degrees.

    When set to 12:17 10:17 8:10 6:3
    Power = 11.0 watts over 5 minutes
    Temp ranged between 60 - 63 degrees.

    It doesn't save power at 800MHz, but 1.1 watts and 4 degrees while in high CPU usage is worth the few minutes to set up PHC undervolting in my opinion.

    If you are using ubuntu here is a great tutorial
    http://ubuntuforums.org/showthread.php?t=786402

    Then I put this into my /etc/rc.local
    Code:
    echo "12:17 10:17 8:10 6:3" > /sys/devices/system/cpu/cpu0/cpufreq/phc_controls
    echo "12:17 10:17 8:10 6:3" > /sys/devices/system/cpu/cpu1/cpufreq/phc_controls
    If anyone tries this please leave feedback.
     
    hardran3, Sep 13, 2008
    #1
    1. Advertisements

  2. hardran3

    axcairns

    Joined:
    Aug 8, 2008
    Messages:
    92
    Likes Received:
    0
    Any idea how much this helps battery life?

    Cheers,

    Allan
     
    axcairns, Sep 15, 2008
    #2
    1. Advertisements

  3. hardran3

    2manydjs

    Joined:
    Jul 16, 2008
    Messages:
    300
    Likes Received:
    0
    Does undervolting have influence on the performance of the Atom? (both in theory and practice)
     
    2manydjs, Sep 16, 2008
    #3
  4. hardran3

    muaB

    Joined:
    Aug 27, 2008
    Messages:
    26
    Likes Received:
    0
    no, undervolting too much will cause the cpu not to work, so most cpus draw a bit more volts as the have to (just to be on the save side).
    what would cuase the cpu speed is the fsb. is the core undervoltet too much, ud have to lower the fsb which causes the cpu to be slower. on the other side, if u would want to make it faster, ud need to set a higher fsb, which would need to overvolt the cpu (thats why all those overclockers need such amazing heatsinks ,p)

    (sry for my poor english ;p)
     
    muaB, Sep 16, 2008
    #4
  5. hardran3

    aabxx

    Joined:
    Aug 9, 2008
    Messages:
    13
    Likes Received:
    0
    At idle with lowest screen brightness I get 7.1 - 7.4 watt.
    At highest brightness it's around 9.5 or something I don't recall exactly.
    When working with documents + browsing at lowest brightness right now it goes up and down between 8 and 9 watts usually.

    I like this idea of undervolting and will look more into it (i would love to get under 7 watts!) but for you, maybe you should look at tweaking other places first?
    EDIT: I see now it wouldn't work at 800 mhz...

    But maybe you're measuring consumption when running heavy apps/doing other fancy stuff I don't know...
     
    aabxx, Sep 17, 2008
    #5
  6. hardran3

    draft

    Joined:
    Jan 1, 2009
    Messages:
    13
    Likes Received:
    0
    PHC works on my AA1 with the latest kernel from sickboy. However, the most I can save under high load is a bit less than 1W. For the number I have, see viewtopic.php?f=28&t=9608&start=130
     
    draft, Jan 23, 2009
    #6
  7. hardran3

    jango

    Joined:
    Aug 2, 2008
    Messages:
    307
    Likes Received:
    0
    Does it worth? because with SICKBOY 0.2 i have problems with sound delay...or not working sound...

    Thanks
     
    jango, Jan 23, 2009
    #7
  8. hardran3

    jango

    Joined:
    Aug 2, 2008
    Messages:
    307
    Likes Received:
    0
    Another question:

    I have applyed all the teaks of powersaving on my rc.local in Ubuntu 8.10, now i have installed SICKBOY Kernel with undervolting support and i have to put on rc.local undervolting config values, should i leave the older powersaving teaks???

    Thanks
     
    jango, Jan 24, 2009
    #8
  9. hardran3

    hardran3

    Joined:
    Aug 11, 2008
    Messages:
    73
    Likes Received:
    0
    Location:
    Swift Current, SK, Canada
    Easy answer. Yes.

    Sickboys's kernel has Intel audio powersaving enabled by default. recompile with that option turned off and your problem will be fixed.
     
    hardran3, Jan 24, 2009
    #9
  10. hardran3

    spinnekopje

    Joined:
    Aug 13, 2008
    Messages:
    83
    Likes Received:
    0
    My AA1 freezes from the moment I do that. It seems I need different values to keep my AA1 running nicely. Most probably I'll try to find them within the next few days...
     
    spinnekopje, Jan 25, 2009
    #10
  11. hardran3

    rlaliberty

    Joined:
    Nov 9, 2008
    Messages:
    19
    Likes Received:
    0
    WOuld there be any reason to do this on a 6 cell battery? Would it save even a negligible amount of time?
     
    rlaliberty, Jan 27, 2009
    #11
  12. hardran3

    hardran3

    Joined:
    Aug 11, 2008
    Messages:
    73
    Likes Received:
    0
    Location:
    Swift Current, SK, Canada
    My AA1 runs much cooler with phc enabled.
     
    hardran3, Jan 27, 2009
    #12
  13. hardran3

    jango

    Joined:
    Aug 2, 2008
    Messages:
    307
    Likes Received:
    0
    Can someone tell that are right values ???
     
    jango, Jan 27, 2009
    #13
  14. hardran3

    exwannabe

    Joined:
    Dec 30, 2008
    Messages:
    42
    Likes Received:
    0
    I believe they are some variations across Atoms. Try cat'ing the phc_default_controls file and see what it says.

    In my case, I get "12:30 10:25 8:20 6:15"

    I changed this to "12:25 10:20 8:15 6:15" and all works fine

    The second number is the voltage (in some form). Try just reducing them somewhat. at first.

    You can not go below the lowest value (15 in my case).
     
    exwannabe, Jan 28, 2009
    #14
  15. hardran3

    jango

    Joined:
    Aug 2, 2008
    Messages:
    307
    Likes Received:
    0
    jango, Jan 30, 2009
    #15
  16. hardran3

    jango

    Joined:
    Aug 2, 2008
    Messages:
    307
    Likes Received:
    0
    bump
     
    jango, Jan 31, 2009
    #16
  17. hardran3

    mrybczyn

    Joined:
    Jan 23, 2009
    Messages:
    1
    Likes Received:
    0
    mrybczyn, Feb 1, 2009
    #17
  18. hardran3

    jango

    Joined:
    Aug 2, 2008
    Messages:
    307
    Likes Received:
    0
    Ok I read the tutorial but the test may cause damage to partitions mounted, as have my HOME partition an SDHC afraid that might be corrupt, it is safe to do the test?
     
    jango, Feb 1, 2009
    #18
  19. hardran3

    BazookaAce

    Joined:
    Nov 23, 2008
    Messages:
    115
    Likes Received:
    0
    Location:
    Bergen, Norway
    68 degrees!? I'm using a stock AAO A150 with Ubuntu 8.10, and the temperature has never gone beyond 45 degrees. Now it's been running for about 12 hours, and the temperature is 40 degrees. I don't use fancontrol and stuff.
     
    BazookaAce, Feb 3, 2009
    #19
  20. hardran3

    hardran3

    Joined:
    Aug 11, 2008
    Messages:
    73
    Likes Received:
    0
    Location:
    Swift Current, SK, Canada
    That is because you are not running at 1.6 GHz with 100% processor used. I maxed out the cpu for these tests using burnMMX, as I stated in my original post.
     
    hardran3, Feb 3, 2009
    #20
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.