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