CentOS 6 : Tip For Significantly Increasing Battery Life / Reducing Power Consumption (Thinkpad X220 Tablet)

Home » CentOS » CentOS 6 : Tip For Significantly Increasing Battery Life / Reducing Power Consumption (Thinkpad X220 Tablet)
CentOS 8 Comments

I was not happy with the power consumption of CentOS 6 x86_64 on a new Lenovo Thinkpad x220 Tablet and I worked on reducing it. I just wanted to share with the list one of the changes which gave me the most significant improvement.

As per http://www.williambrownstreet.net/blog/?p87, add the following kernel arguments to the GRUB boot configuration:

pcie_aspm=force i915.i915_enable_rc6=1 i915.lvds_downclock=1 i915.i915_enable_fbc=1

(in /boot/efi/EFI/redhat/grub.conf since I use EFI, /boot/grub/grub.conf otherwise)

As measured using PowerTop, this made the power consumption decrease from 20W to 11W ! (I had already decreased it from 25W to 20W with the usual tips of disabling hardware, shutting down services, switching tuned profiles, etc.)

All in all, battery time was more than multiplied by two, and the computer is now much more silent since the fan is not always running like mad in order to cool the processor. The bottom of the laptop is not anymore hot as hell.

I don’t know whether this would have an impact on other hardware, but it may be worth looking at it (even on servers?), since the above link points to descriptions of a regression in the kernel which seems more general.

As a side note, the Power Management Guide of Red Hat is a good resource (analysis tools + tuned profiles): http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html-single/Power_Management_Guide/


PS: Do you think I should book a bug in the upstream bug tracker?

8 thoughts on - CentOS 6 : Tip For Significantly Increasing Battery Life / Reducing Power Consumption (Thinkpad X220 Tablet)

  • I did not notice any change in performance so far.
    (Tested with parallelized, offline, Java build and unit tests)

  • I have made many tests with tuned and written small scripts to switch from one profile to the other (laptop-battery-powersave on battery, default on AC). Gains where in the 1W to 2W range vs. 9W gain with the kernel arguments (which is nice now that I’m around 12W, but it was 25W at the beginning!)

    They are related to Intel graphic drivers (follow links in OP):

    I don’t know much more, but what I know is that this single change increased battery life on my laptop by a factor of two, that the fan is not running at full speed all the time (it also was on AC), and that nothing was broken for the last two days I have been working with it.

    Definitely, these could be bad options for some users (or, more likely, irrelevant ones). I posted to the list, so that when somebody will search for ‘CentOS 6 thinkpad power consumption too high’ he will bump into the Ubuntu related post I linked to (which provides additional links to the root cause) but also that this person will see that it worked pretty well in my particular case.

    The above links rather point to a regression.

    I assume that CentOS users are experienced enough to do their own risks/benefits analysis before applying such tweaks. We can probably agree that we disagree on that point.

  • Thanks for the tips. I’ve got a X220 and power consumption is typically less than 10W, with various powertop tweaks on Fedora 17, giving me
    8-9hrs of battery life.

    The biggest win was setting i915.i915_enable_rc6=1 on the kernel command line, although I’ve read that this can cause some instability, depending on you kernel and usage — had a couple of crashes/freezes a 6 months ago, but it seems pretty stable now. The benefits for a laptop definitely out-weigh the inconvenience or a few rare freezes, but it would be different for a server.

    Might try out the other kernel line options and see if I can do better :-)

    Here’s my /etc/rc.d/rc.local file in case you are interested:

  • Just a quick note to say that I’m indeed experiencing stability issues. The X server sometimes freezes and I have to reboot. Also Firefox crashes more often than not.

    I’m slowly trying to find out if this is due to these kernel arguments or to the combination with Compiz and docking etc. I’ll post it here, if I gather more information.

    As James pointed out, caution is required before applying these kernel arguments.

  • As a follow-up: since the update to 6.4, these kernel arguments are
    *no longer required* in order to have a reasonable power consumption on a Thinkpad X220.

    With tuned profile ‘laptop-battery-powersave’, the idle laptop consumes a bit more than 10W (with display turned of: 8W)