Power management

From ArchWiki
Revision as of 03:58, 27 December 2012 by Daniel.noland (Talk | contribs) (Where To Change Power Settings)

Jump to: navigation, search

Tango-document-new.pngThis article is a stub.Tango-document-new.png

Notes: The purpose of this article currently overlaps other introductions like General Recommendations#Power management and Laptop#Power Management; application-specific information must be moved to the respective articles; only a generic introduction to power management in Arch and to related articles should stay here. (Discuss in Talk:Power management#)

The aim of this page is to try to gather all the informations which are available on the topic of linux power management features. There are several places where one can change power management settings:

Power settings you set in one place could be overwritten in another place.

Power saving

See power saving.

Where To Change Power Settings

One can pass a kernel command line parameter in the boot loader to activate power management features in certain kernel modules. If you are using systemd you can change some power management options in systemd config files or execute your own config file. pm-utils and upower work together. pm-utils is responsible for changing the power management options while upower informs pm-utils about system changes. For example, if you unplug your laptop from AC power then upower will signal to pm-utils that the laptop is running on battery. This will cause pm-utils to change some power management options according to its config files.

Have a look at the power management category to get an overview on what power management options exists in Archlinux:.

Kernel Command Line Parameters

Append the lines to your kernel command line parameter to enable these options. If you change settings for kernel modules make sure they are either compiled into your initrd (insert module name in MODULES in /etc/mkinitcpio.conf) or pass an option via a modprobe config file (Kernel_modules#Using_files_in_.2Fetc.2Fmodprobe.d.2F).



Enable RC6 Power Save Options


Where #Nr:

  • 1: enable rc6
  • 3: enable rc6 and deep rc6
  • 5: enable rc6 and deepest rc6
  • 7: enable rc6, deep and deepest rc6

Change Usbcore Autosuspend Time


pm-utils Settings

The pm-utils (see also: Pm-utils#Power_saving) package provides quirks for suspend to RAM and suspend to disk but also includes some scripts for power management. You need upower which registers power changes and signals that information to pm-utils.

Enable SATA Link Power Management

Execute the following command to enable SATA link power management when on battery:

 # echo SATA_ALPM_ENABLE=true > /etc/pm/config.d/sata_alpm

Scripts For Pm-utils Which Enable Power Management Options

These scripts have to be made executable via

 # chmod +x <script file>


Connection problems with Atheros AR9485 Wireless Network Adapter

You may experience connection problems with the Atheros AR9485 Wireless Network Adapter, which is caused by incorrect power management functioning. You can notice the problem if you're experiencing random disconnections in IM or other software that keeps connection alive for a long time. In case you're using laptop, first you must disable battery power-over-perfomance feature: Settings / Power Manager / On Battery / Prefer power savings over perfomance

Next thing to do is switch off power management for adapter: You should add

iwconfig wlan0 power off
(assuming wlan0 is your AR9485 adapter) anywhere it can be executed on system init (or simply run it once, to fix the problem for current session) and that should do it.

See Also

CPU Frequency Scaling