Results 1 to 3 of 3

Thread: new kernels take more power

  1. #1
    Join Date
    Nov 2005
    Location
    USA
    Beans
    38
    Distro
    Ubuntu 14.04 Trusty Tahr

    new kernels take more power

    I notice that my system (Compaq 6715b) idle power goes up with new kernels.
    I start the system, disable bluet1ooth (sudo hciconfig hci0 down) and set ati driver to power state 1 (sudo aticonfig --set-powerstate=1).
    Next I run powertop and wait until the display dims, then I wait for powertop to update 3 times and record the power.

    Wakeups-from-idle per second : 137.1 interval: 10.0s
    Power usage (ACPI estimate): 14.5W (3.4 hours)
    2.6.24-16-generic

    Wakeups-from-idle per second : 153.0 interval: 10.0s
    Power usage (ACPI estimate): 16.7W (2.9 hours)
    2.6.24-18-generic

    Wakeups-from-idle per second : 142.1 interval: 10.0s
    Power usage (ACPI estimate): 15.9W (2.9 hours)
    2.6.24-19-generic

    I see the fewest wake-ups per sec with the 2.6.24-16-generic kernel and the lowest power.
    Battery life is important so I went back to the old kernel.
    I changed the /grub/menu.lst to make the default kernel 2.6.24-16-generic.
    Computer
    CPU i5-4460 , Motherboard GA-B85M-DS3H-A
    8GB Memory, 1TB /Home, 128GB SSD /
    Samsung 19" DVI, Acer 19" VGA

  2. #2
    Join Date
    Jan 2007
    Location
    $here ? $here : $there
    Beans
    3,717
    Distro
    Ubuntu 8.04 Hardy Heron

    Re: new kernels take more power

    I don't think it's generally the case that newer kernels are inherently worse for power savings (in fact, they are often better). As a better test, I would cleanly boot the machine with a particular kernel, log in, use the power savings features you mentioned, wait 1-2 minutes and then, with no windows open (well, a terminal) and the machine completely idle:

    Code:
    sudo powertop -d -t 300
    Let the machine sit for 5 minutes without touching it (that command lets powertop run for 5 minutes and then dumps the output) and then compare those numbers over all three kernels.

    Also, to find out more about power savings, check www.lesswatts.org
    Don't try to make something "fast" until you are able to quantify "slow".

  3. #3
    Join Date
    Nov 2005
    Location
    USA
    Beans
    38
    Distro
    Ubuntu 14.04 Trusty Tahr

    Re: new kernels take more power

    I re-ran the test using your recommended procedure and this is what I get.


    Wakeups-from-idle per second : 156.2 interval: 300.0s
    Power usage (ACPI estimate): 15.8W (3.2 hours)
    2.6.24-16-generic

    Wakeups-from-idle per second : 158.7 interval: 300.0s
    Power usage (ACPI estimate): 17.8W (2.7 hours)
    2.6.24-18-generic

    Wakeups-from-idle per second : 155.2 interval: 300.0s
    Power usage (ACPI estimate): 15.8W (3.0 hours)
    2.6.24-19-generic

    I ran update manager before I started.
    I ran a script which turns off hci0 and set ati powerstate to 1.
    then I waited 1 min and ran powertop -d -t 300.
    between and before runs I charged the battery.
    Computer
    CPU i5-4460 , Motherboard GA-B85M-DS3H-A
    8GB Memory, 1TB /Home, 128GB SSD /
    Samsung 19" DVI, Acer 19" VGA

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •