X301 Power Savings

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x301 Power Savings

The standard Fedora configuration provides for a lot of leeway in power savings. Here are the items I have modified that got me from around 11W to around 7W. powertop is an invaluable tool in figuring out how much power is being drawn by each component, not to mention seeing your progress. A lot of this information is covered in other pages, but this is specific to the x301. Note that these settings were tested on an x301 running a fresh Fedora 11 Beta install.

  • I don't use bluetooth on a regular day...

echo disabled > /proc/acpi/ibm/bluetooth

  • The video system keeps one or more of the external connectors powered up at all times.

Anything with a '*' next to the mode is powered on:

[root@x301 ~]# xrandr 
Screen 0: minimum 320 x 200, current 1440 x 900, maximum 8192 x 8192
VGA1 connected (normal left inverted right x axis y axis)
  1024x768       60.0  
  800x600        60.3  
  640x480        59.9  
LVDS1 connected 1440x900+0+0 (normal left inverted right x axis y axis) 287mm x 180mm
  1440x900       60.0*+   50.0  
DVI1 disconnected (normal left inverted right x axis y axis)
DVI2 connected (normal left inverted right x axis y axis)
  1024x768       60.0*  
  800x600        60.3  
  640x480        59.9 

So disable them with

xrandr --output DVI2 --off

  • By default, the wifi driver keeps the card at the maximum power setting for better performance. If you are just browsing the web or not using a lot of bandwidth significant savings can be had by reducing this setting.1

echo 5 > /sys/class/net/wlan0/device/power_level

  • Newer kernels are much smarter about how they load the cores on a CPU, this setting tells it to be more power efficient rather than performance oriented.2

echo 1 > /sys/devices/system/cpu/sched_mc_power_savings

  • Hal will constantly poll the cdrom to see if a disk has been inserted and if it should mount and open it for you in X. Disabling this allows the cpu to sleep longer.

hal-disable-polling --device /dev/cdrom

  • New features in the SATA driver allows it to power down the link when not utilized, make sure to enable on all paths with3

for foo in /sys/class/scsi_host/host*/link_power_management_policy;
do echo min_power > $foo;

  • Similar savings can be had by setting the pcie bus to a more power-friendly mode

echo powersave > /sys/module/pcie_aspm/parameters/policy

  • The sound hardware also has power savings settings

echo 5 > /sys/module/snd_hda_intel/parameters/power_save
echo Y > /sys/module/snd_hda_intel/parameters/power_save_controller

  • Turning off Wake-On-Lan will save some power while your system is suspended or hibernated

ethtool -s eth0 wol d

  • Powering down the usb bus while not in use is also beneficial



External Resources