Thursday, February 9, 2012

Linux kernel 3.2.5 fixed problems with energy consumption

The new release of Linux kernel finally fixed power regression and overheating. This bug comes from early 2.6.38 kernel and concerns great power consumption and overheating. There are many attempts for fixing it, including famous

acpi_osi="Linux" pcie_aspm=force boot line parameters.

I use them since 2.6.39 on my Arch Linux box and various Ubuntu instalations and I can say it partially works. Especially it works well on ArchLinux but not so good on Ubuntu or even OpenSuse.
But this new release has a patch, which solves the problem. Here is an announcement by Greg Kroah-Hartman about this patch. It will be available on 3.3 series and new Ubuntu and Fedora releases will benefit it.
The patch isn't tested very well (except on bleeding edge Fedora kernels). Greg says he is confident it will works. I want to believe him to.

The newly kernel 3.2.5 is also in Arch repos. I did not install it yet, but I will and I will use it very soon. Too bad I waste so much time in compiling 3.2.2 with GobiHide patch. Any way, I will do it one more time and I hope this newly 3.2.5 kernel will be the base for my AmeLinux distro.


  1. In my case (I have a Lenovo T60 laptop) the new kernel actually increased the power consumption by 25% (from 16W on idle to 20W on idle)! Note: I've been using the pcie_aspm=force kernel option since 2.6.39.

  2. What was your previous kernel version?
    Do you have laptop-mode-tools installed and running?

  3. I had 3.2.4-1. I also have laptop-mode-tools running. I don't see anything unusual in Powertop2 apart from the increased power consumption. I was wondering if you had a chance to install the new kernel and experienced something similar.

  4. Yes, I've installed 3.2.5 and I can't see any difference. I'm really in doubt about power regression fixes. Powertop2 gives me same consumptions ~11-13W on idle (compiz, KDE, chromium with 6-8 light pages open, display backlight at very low position, wireless on). Actually it gives me 1.28W, but I think the right value is 12.8W. My computer is Compaq 610 Laptop (CPU Celeron T1500 1.86GHz), no CPU governors loaded, cause they seems to not work at all.