Minimizing Power Consumption in Linux - Revision history

J at 20:30, 20 June 2008

2008-06-20T20:30:19Z

2007-12-27T05:48:29Z

‎Hardware Settings

2007-12-27T04:49:11Z

2007-12-17T22:49:15Z

‎Laptop-Mode

2007-12-17T04:23:52Z

‎CD-ROM Auto Poll

2007-12-17T04:23:37Z

‎CD-ROM Auto Poll

2007-12-17T04:23:20Z

‎CD-ROM Auto Poll

2007-12-17T01:02:29Z

‎Wireless Powersave Mode

2007-12-17T01:02:04Z

‎Wireless Powersave Mode

2007-12-17T00:43:31Z

‎The Linux "tickless" Kernel Feature

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 [[Category:Ubuntu]]
 [[Category:Ubuntu7.10]]
 Want to make your laptop battery last longer?  Want to lower the power consumption of that awesome Linux based media PC you have?  Here's where to start.
 This article is written specifically for Ubuntu 7.10 (Gusty Gibbon), but the ideas expressed here can apply to any Linux distribution.  Some of the higher-level thought can even be applied to other operating systems.
+|valign="top" |
 {{Incomplete2|Still working on finding ways to save power|Need to finish documenting others}}

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 ===Hardware Settings===
 It's possible to configure certain pieces of physical hardware to minimize power consumption.
 ====CD-ROM Auto Poll====
 The idea of this setting is to detect CDs or memory sticks being inserted or removed.  We can shut off the auto-poll for all drives to save even more power.  Keep in mind, this will affect any auto-mounting/program launching features that you have in place in your distribution.
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 </pre>
 [https://bugs.launchpad.net/ubuntu/+source/powertop/+bug/136549 apparently, it doesn't work in Ubuntu anyway]
 ===Automated Actions===
 ====File Access Time Update====

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 <pre>
 sudo hal-disable-polling --device /dev/scd0 --enable-polling
 </pre>
 ''PowerTOP detects this, and provides a shortcut key to turn off auto-poll.''
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 Note that decreasing the transmission power of your wireless device will decrease the device's effectiveness.  Try modes between 1 and 5 if you have problems - 1 for minimal power savings, 5 for maximum.
 <br><br>
-To undo this, set the power mode back to 6 (which is the same as mode 0):
+To undo this, set the power mode back to 0 (which is the same as mode 6):
 <pre>
-iwpriv eth1 set_power 6
+iwpriv eth1 set_power 0
 </pre>

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 ''PowerTOP detects this, and suggests this procedure.''
 ===Laptop-Mode===
-Laptop-mode allows you to switch your laptop in and out of power-saving mode automatically when power is disconnected or connected.  Need to figure out how to configure it.<ref>http://www.mjmwired.net/kernel/Documentation/laptop-mode.txt</ref>
+Laptop-mode, officially called "laptop-mode-tools", allows you to switch your kernel in and out of power-saving mode automatically when power is disconnected or connected.  The basic functionality is to spin down the hard drive when it's not in use, but it's also able to automatically enable/disable software services.  Laptop-mode is disabled by default in Ubuntu.
 <pre>
 /etc/laptop-mode/
 </pre>
-[http://ubuntudemon.wordpress.com/2007/10/26/laptop-hardrive-killer-bug/#comment-31234 major configuration bug with laptop-mode relating to hard drives]
 ==References==
 <references/>

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 sudo hal-disable-polling --device /dev/scd0 --enable-polling
 </pre>
 ''PowerTOP detects this, and provides a shortcut key to turn off auto-poll.''

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 ''PowerTOP detects this, and provides a simple method for you to turn off auto-poll.''
 ====Wireless Powersave Mode====
-Wireless transmission takes a huge amount of power.  If you don't need as much power - for instance, your laptop never gets very far from your access point - we can turn the transmission power down.
+Wireless transmission takes a huge amount of power.  If you don't need as much power - for instance, you're just browsing the web - we can turn the power saving mode to maximum, causing the wireless card to go into a sleep state when not in use:
 <pre>
 iwpriv eth1 set_power 5
 </pre>
-Note that decreasing the transmission power of your wireless device will decrease the device's effectiveness.
+Note that decreasing the transmission power of your wireless device will decrease the device's effectiveness.  Try modes between 1 and 5 if you have problems - 1 for minimal power savings, 5 for maximum.
 <br><br>
-''PowerTOP detects this, and provides a simple method for you to turn down the power temporarily.''
+''PowerTOP detects this, and provides a simple method for you to turn on power saving mode.''
 ====USB autosuspend====
 PowerTOP suggests this, I'm not sure exactly what it does yet:

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 ==How to Reduce Power Consumption==
 ===The Linux "tickless" Kernel Feature===
-Google this great feature.
+Also called ''CONFIG_NO_HZ'' or ''Dynamic Ticks'', this feature eliminates unnecessary timer ticks, resulting in lower CPU work, which in turn lowers power consumption and heat output.  This feature has been available since the 2.6.21 kernel, and is usually enabled by default.
 ===Intel PowerTOP===
 [http://www.intel.com/ Intel] makes an open source tool, called [http://www.linuxpowertop.org/ PowerTOP], which allows you to see which processes are forcing the computer to jump out of power save mode.  It also gives recommendations for other ways to save power and will even automatically implement some of the suggested measures for you if you like.