Page 1 of 3 123 LastLast
Results 1 to 10 of 22

Thread: Linux Kernel Power Bug Now High Importance In Ubuntu

  1. #1
    Join Date
    Jan 2007
    Posts
    15,389

    Default Linux Kernel Power Bug Now High Importance In Ubuntu

    Phoronix: Linux Kernel Power Bug Now High Importance In Ubuntu

    The bug introduced during the development of the Linux 2.6.38 kernel causing excessive power consumption is very real, is occurring on many different hardware platforms, and has just been deemed a bug of high importance by the Ubuntu Kernel Team. This serious regression was just made widely known on Friday in my Mobile Users Beware: Linux Has Major Power Regression article and then further detailed in The Tests Showing Ubuntu 11.04 On A Power Consumption Binge...

    http://www.phoronix.com/vr.php?view=OTM3NQ

  2. #2
    Join Date
    Apr 2011
    Posts
    20

    Default scheduler

    Maybe its because of recent changes in scheduler. All in all its a shame!

  3. #3

    Default

    Ugh .. Still no evidence but the sky is certainly falling.

    Lenovo T400
    Fuduntu 14.9 (64bit)
    Kernel 2.6.38.4
    Completely idle on battery for ~15 minutes.
    6.36 Watts, 108 wakeups per second.



    Asus Eee PC 1015PEM
    Fuduntu 14.9 (32bit)
    Kernel 2.6.38.4
    Completely idle on battery (as before)
    7.31 Watts, 135.8 wakeups per second.



    As you can see from the images, even my Thinkpad is using only 6ish watts, and well under 200 wakeups per second (closer to 100 really!)..

    The only reason there are 33 reports is because you asked people in your forum to report it!

    http://phoronix.com/forums/showthrea...105#post201105

    Lets take a look at the data supplied in that bug report

    Code:
    Wakeups-from-idle per second : 542.9    interval: 10.0s
    Power usage (ACPI estimate): 14.1W (2.4 hours) (long term: 14.7W,/2.3h)
    
    Top causes for wakeups:
      25.7% (155.8)   [i915] <interrupt>
      13.3% ( 80.3)D  chromium-browse
      17.9% (108.5)   [extra timer interrupt]
       5.7% ( 34.7)   [iwlagn] <interrupt>
       5.1% ( 31.2)   PS/2 keyboard/mouse/touchpad interrupt
       5.0% ( 30.2)   [kernel scheduler] Load balancing tick
       4.9% ( 29.9)   kworker/0:0
       4.4% ( 26.5)   [Rescheduling interrupts] <kernel IPI>
       3.3% ( 20.1)   compiz
       0.0% (  0.0)D  flush-8:0
       3.2% ( 19.6)   desktopcouch-se
       0.1% (  0.7)D  ntop
       1.2% (  7.3)D  thunderbird-bin
       1.7% ( 10.0)   gwibber-service
       1.6% (  9.9)   ubuntuone-syncd
       1.4% (  8.6)   [TLB shootdowns] <kernel IPI>
       1.4% (  8.3)   [acpi] <interrupt>
       0.6% (  3.9)   [ahci] <interrupt>
    The program 'flush-8:0' is writing to file 'ECRYPTFS_FNEK_ENCRYPTED.FWY-tcU' on /dev/sda1.
    This prevents the disk from going to powersave mode.
    - https://launchpadlibrarian.net/69300044/hardcopy.0

    Code:
      25.7% (155.8)   [i915] <interrupt>
      13.3% ( 80.3)D  chromium-browse
      17.9% (108.5)   [extra timer interrupt]
       5.1% ( 31.2)   PS/2 keyboard/mouse/touchpad interrupt
    These are all related.

    375.8 wakeups per second contribute to applications

    What's not reported in the bug though (and probably the root cause), top output.

  4. #4

    Default

    Oh, and .. PowerTOP version 1.13

    PowerTOP 1.97 is required to take report on and take advantage of the new powersaving features of kernel 2.6.37 and newer.

    http://lists.lesswatts.org/pipermail...ry/000509.html

    The most common of these have been built into Jupiter.

    Has the Phoronix test suite been updated to use the kernel "perf" infrastructure?

  5. #5
    Join Date
    Mar 2009
    Location
    in front of my box :p
    Posts
    817

    Default

    So is this a bug that affects all kernels or just Ubuntu patched ones? I don't understand this fixation on Ubuntu here (and generally). If this happens in vanilla kernels it should not just be reported to Ubuntu but to upstream Kernel development and maybe other distributors. Or did I miss something?

  6. #6
    Join Date
    Jan 2008
    Location
    Have a good day.
    Posts
    678

    Default

    Quote Originally Posted by fewt View Post
    Ugh .. Still no evidence but the sky is certainly falling.
    Did you see the plots?

  7. #7

    Default

    Quote Originally Posted by yotambien View Post
    Did you see the plots?
    Yes. It doesn't change my opinion (or my evidence) that this is not a kernel problem.

  8. #8
    Join Date
    Jan 2008
    Location
    Have a good day.
    Posts
    678

    Default

    Quote Originally Posted by fewt View Post
    Yes. It doesn't change my opinion (or my evidence) that this is not a kernel problem.
    It was rhetorical. I assume you read the article and saw the plots. How do you explain them?

  9. #9

    Default

    Quote Originally Posted by yotambien View Post
    It was rhetorical. I assume you read the article and saw the plots. How do you explain them?
    I can't explain them (there isn't enough data), however I believe that the problem could be:

    A) The build options between kernel versions may be different
    B) Something in userspace
    C) The Phoronix test suite itself
    (2.6.37 pretty much required a new version of Powertop, Phoronix test suite probably also needs an update)
    D) The kernel doesn't tune itself for power / battery (requiring a userspace tool like Jupiter)

    It is most likely that this is just a misconfiguration blown grossly out of proportion.

  10. #10

    Default

    Quote Originally Posted by fewt View Post
    C) The Phoronix test suite itself
    (2.6.37 pretty much required a new version of Powertop, Phoronix test suite probably also needs an update)
    Nope, it doesn't need any update. And users have reported the issue independent of PTS - hence the original Canonical bug report completely independent of that, etc. Most users don't even know how to use the power monitoring features in PTS.

Posting Permissions

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