On 03/08/12 08:05, Mathieu Baudier wrote:
> Hello,
>
> 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/?p=387, 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/
>
> Cheers,
>
> Mathieu
>
> PS: Do you think I should book a bug in the upstream bug tracker?
Rather than filing a bug upstream, I would think it more appropriate to
document the various settings on the CentOS Wiki in the laptops section:
http://wiki.centos.org/HowTos/Laptops
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