[CentOS] CentOS 6 : Tip for significantly increasing battery life / reducing power consumption (Thinkpad X220 Tablet)

On 03/08/12 17:05, Mathieu Baudier wrote:
> 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
>
> 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.)

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:
-------------------------------------
#!/bin/bash

echo 5 > /proc/sys/vm/laptop_mode
echo 0 > /proc/sys/kernel/nmi_watchdog
echo 1 > /sys/devices/system/cpu/sched_mc_power_savings
echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs
for i in /sys/bus/usb/devices/*/power/autosuspend; do echo 1 > $i; done
for i in /sys/bus/usb/devices/*/power/level; do echo auto > $i; done
echo min_power > /sys/class/scsi_host/host0/link_power_management_policy
echo min_power > /sys/class/scsi_host/host1/link_power_management_policy
echo Y > /sys/module/snd_hda_intel/parameters/power_save_controller
echo 1 > /sys/module/snd_hda_intel/parameters/power_save
for i in /sys/bus/{pci,i2c}/devices/*/power/control; do echo auto > $i; done

iwconfig wlan0 power on
-------------------------------------

Cheers,

Kal

-- 
Kahlil (Kal) Hodgson                       GPG: C9A02289
Head of Technology                         (m) +61 (0) 4 2573 0382
DealMax Pty Ltd                            (w) +61 (0) 3 9008 5281

Suite 1415
401 Docklands Drive
Docklands VIC 3008 Australia

"All parts should go together without forcing.  You must remember that
the parts you are reassembling were disassembled by you.  Therefore,
if you can't get them together again, there must be a reason.  By all
means, do not use a hammer."  -- IBM maintenance manual, 1925