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

[Kahlil Hodgson]

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

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