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Rewrite some parts around the cpufreq comparison table. I missed these in the last commit when I switched stuff over to cpufrequtils as the default. Also added more examples on how to use cpufrequtils to show its flexibility. Other improvements elsewhere.

1 swift 1.1 <?xml version='1.0' encoding="UTF-8"?>
2     <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3 nightmorph 1.41 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/power-management-guide.xml,v 1.40 2009/08/05 14:51:17 nightmorph Exp $ -->
4 so 1.15 <guide link="/doc/en/power-management-guide.xml">
5 swift 1.1 <title>Power Management Guide</title>
6    
7 swift 1.4 <author title="Author">
8 nightmorph 1.17 <mail link="earthwings@gentoo.org">Dennis Nienhüser</mail>
9 swift 1.1 </author>
10 rane 1.19 <author title="Editor">
11     <mail link="chriswhite@gentoo.org">Chris White</mail>
12     </author>
13 nightmorph 1.26 <author title="Editor">
14     <mail link="nightmorph@gentoo.org">Joshua Saddler</mail>
15     </author>
16 swift 1.1
17     <abstract>
18     Power Management is the key to extend battery run time on mobile systems like
19     laptops. This guide assists you setting it up on your laptop.
20     </abstract>
21    
22     <!-- The content of this document is licensed under the CC-BY-SA license -->
23 so 1.15 <!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
24 swift 1.1 <license/>
25    
26 nightmorph 1.41 <version>1.44</version>
27     <date>2009-08-11</date>
28 swift 1.1
29     <chapter>
30     <title>Introduction</title>
31     <section>
32     <body>
33    
34     <p>
35 so 1.15 Capacity and lifetime of laptop batteries have improved much in the last years.
36 swift 1.1 Nevertheless modern processors consume much more energy than older ones and
37     each laptop generation introduces more devices hungry for energy. That's why
38     Power Management is more important than ever. Increasing battery run time
39     doesn't necessarily mean buying another battery. Much can be achieved applying
40     intelligent Power Management policies.
41     </p>
42    
43     </body>
44     </section>
45     <section>
46 rane 1.19 <title>A Quick Overview</title>
47 swift 1.1 <body>
48    
49     <p>
50     Please notice that this guide describes Power Management for <e>laptops</e>.
51     While some sections might also suite for <e>servers</e>, others do not and may
52     even cause harm. Please do not apply anything from this guide to a server
53     unless you really know what you are doing.
54     </p>
55    
56     <p>
57     As this guide has become rather long, here's a short overview helping you to
58     find your way through it.
59     </p>
60    
61     <p>
62 rane 1.19 The <uri link="#doc_chap2">Prerequisites</uri> chapter talks about some
63     requirements that should be met before any of the following device individual
64     sections will work. This includes BIOS settings, kernel configuration and some
65     simplifications in user land. The following three chapters focus on devices
66     that typically consume most energy - processor, display and hard drive. Each
67     can be configured seperately. <uri link="#doc_chap3">CPU Power Management</uri>
68     shows how to adjust the processor's frequency to save a maximum of energy
69 rane 1.21 without losing too much performance. A few different tricks prevent your hard
70 rane 1.19 drive from working unnecessarily often in <uri link="#doc_chap5">Disk Power
71     Management</uri> (decreasing noise level as a nice side effect). Some notes on
72 rane 1.20 graphics cards, Wireless LAN and USB finish the device section in <uri
73     link="#doc_chap6">Power Management For Other Devices</uri> while another
74 rane 1.19 chapter is dedicated to the (rather experimental) <uri link="#doc_chap7">sleep
75 rane 1.20 states</uri>. Last not least <uri link="#doc_chap8">Troubleshooting</uri> lists
76     common pitfalls.
77 swift 1.1 </p>
78    
79     </body>
80     </section>
81     <section>
82 rane 1.19 <title>Power Budget For Each Component</title>
83 swift 1.1 <body>
84    
85 swift 1.2 <figure link="/images/energy-budget.png" short="Which component consumes how
86 swift 1.1 much energy?" caption="Power budget for each component"/>
87    
88     <p>
89     Nearly every component can operate in different states - off, sleep, idle,
90     active to name a few - consuming a different amount of energy. Major parts are
91     consumed by the LCD display, CPU, chipset and hard drives. Often one is able to
92     activate OS-independent Power Management in the BIOS, but an intelligent setup
93     in the operating system adapting to different situations can achieve much more.
94     </p>
95    
96     </body>
97     </section>
98     </chapter>
99    
100     <chapter>
101     <title>Prerequisites</title>
102     <section>
103     <body>
104    
105     <p>
106 nightmorph 1.17 Before discussing the details of making individual devices Power Management
107 rane 1.20 aware, make sure certain requirements are met. After controlling BIOS settings,
108     some kernel options want to be enabled - these are in short ACPI, sleep states
109     and CPU frequency scaling. As power saving most of the time comes along with
110     performance loss or increased latency, it should only be enabled when running
111     on batteries. That's where a new runlevel <e>battery</e> comes in handy.
112 swift 1.1 </p>
113    
114     </body>
115     </section>
116     <section>
117 rane 1.19 <title>The BIOS Part</title>
118 swift 1.1 <body>
119    
120     <p>
121     First have a look into your BIOS Power Management settings. The best way is to
122     combine BIOS and operating system policies, but for the moment it's better to
123     disable most of the BIOS part. This makes sure it doesn't interfere with your
124     policies. Don't forget to re-check BIOS settings after you configured
125     everything else.
126     </p>
127    
128     </body>
129     </section>
130     <section>
131 rane 1.19 <title>Setting USE Flags</title>
132 nightmorph 1.17 <body>
133    
134     <p>
135     Please check that the <c>acpi</c> USE flag is set in
136     <path>/etc/make.conf</path>. Other USE flags that might be interesting for your
137     system are <c>apm</c>, <c>lm_sensors</c>, <c>nforce2</c>, <c>nvidia</c>,
138     <c>pmu</c>. See <path>/usr/portage/profiles/use*.desc</path> for details. If
139     you forgot to set one of these flags, you can recompile affected packages using
140 rane 1.19 the <c>--newuse</c> flag in <c>emerge</c>, see <c>man emerge</c>.
141 nightmorph 1.17 </p>
142    
143     </body>
144     </section>
145     <section>
146 rane 1.19 <title>Configuring The Kernel</title>
147 swift 1.1 <body>
148    
149     <p>
150     ACPI (Advanced Configuration and Power Interface) support in the kernel is
151     still work in progress. Using a recent kernel will make sure you'll get the
152     most out of it.
153     </p>
154    
155     <p>
156 rane 1.20 There are different kernel sources in Portage. I'd recommend using
157 jkt 1.33 <c>gentoo-sources</c> or <c>tuxonice-sources</c>. The latter contains patches
158 jkt 1.34 for TuxOnIce, see the chapter about <uri link="#doc_chap7">sleep states</uri>
159     for more details. When configuring the kernel, activate at least these options:
160 swift 1.1 </p>
161    
162     <pre caption="Minimum kernel setup for Power Management (Kernel 2.6)">
163 nightmorph 1.39 Power management and ACPI options ---&gt;
164 nightmorph 1.40 [*] Power Management support
165 swift 1.1 [ ] Software Suspend
166    
167     ACPI( Advanced Configuration and Power Interface ) Support ---&gt;
168 nightmorph 1.39 [ ] Deprecated /proc/acpi/ files
169 neysx 1.12 [*] AC Adapter
170     [*] Battery
171 swift 1.1 &lt;M&gt; Button
172 so 1.15 &lt;M&gt; Video
173     [ ] Generic Hotkey
174 swift 1.1 &lt;M&gt; Fan
175     &lt;M&gt; Processor
176     &lt;M&gt; Thermal Zone
177     &lt; &gt; ASUS/Medion Laptop Extras
178 so 1.15 &lt; &gt; IBM ThinkPad Laptop Extras
179 swift 1.1 &lt; &gt; Toshiba Laptop Extras
180 so 1.15 (0) Disable ACPI for systems before Jan 1st this year
181 swift 1.1 [ ] Debug Statements
182 so 1.15 [*] Power Management Timer Support
183     &lt; &gt; ACPI0004,PNP0A05 and PNP0A06 Container Driver (EXPERIMENTAL)
184 rane 1.20
185 swift 1.1 CPU Frequency Scaling ---&gt;
186     [*] CPU Frequency scaling
187 so 1.15 [ ] Enable CPUfreq debugging
188     &lt; &gt; CPU frequency translation statistics
189     [ ] CPU frequency translation statistics details
190 swift 1.1 Default CPUFreq governor (userspace)
191     &lt;*&gt; 'performance' governor
192     &lt;*&gt; 'powersave' governor
193 swift 1.8 &lt;*&gt; 'ondemand' cpufreq policy governor
194 so 1.15 &lt;*&gt; 'conservative' cpufreq governor
195 swift 1.1 &lt;*&gt; CPU frequency table helpers
196     &lt;M&gt; ACPI Processor P-States driver
197     &lt;*&gt; <i>CPUFreq driver for your processor</i>
198     </pre>
199    
200     <p>
201 so 1.15 Decide yourself whether you want to enable Software Suspend, and Sleep States
202     (see below). If you own an ASUS, Medion, IBM Thinkpad or Toshiba laptop, enable
203 neysx 1.12 the appropriate section.
204 swift 1.8 </p>
205    
206     <p>
207 rane 1.20 The kernel has to know how to enable CPU frequency scaling on your processor.
208     As each type of CPU has a different interface, you've got to choose the right
209 rane 1.19 driver for your processor. Be careful here - enabling <c>Intel Pentium 4 clock
210     modulation</c> on a Pentium M system will lead to strange results for example.
211 swift 1.8 Consult the kernel documentation if you're unsure which one to take.
212 swift 1.1 </p>
213    
214     <p>
215     Compile your kernel, make sure the right modules get loaded at startup and boot
216 rane 1.20 into your new ACPI-enabled kernel. Next run <c>emerge sys-power/acpid</c> to
217     get the acpi daemon. This one informs you about events like switching from AC
218     to battery or closing the lid. Make sure the modules are loaded if you didn't
219     compile them into the kernel and start acpid by executing <c>/etc/init.d/acpid
220     start</c>. Run <c>rc-update add acpid default</c> to load it on startup. You'll
221     soon see how to use it.
222 swift 1.1 </p>
223    
224     <pre caption="Installing acpid">
225 yoswink 1.10 # <i>emerge sys-power/acpid</i>
226 swift 1.1 # <i>/etc/init.d/acpid start</i>
227     # <i>rc-update add acpid default</i>
228     </pre>
229    
230     </body>
231     </section>
232     <section>
233 rane 1.19 <title>Creating A "battery" Runlevel</title>
234 swift 1.1 <body>
235    
236     <p>
237     The default policy will be to enable Power Management only when needed -
238     running on batteries. To make the switch between AC and battery convenient,
239 rane 1.19 create a runlevel <c>battery</c> that holds all the scripts starting and
240 swift 1.1 stopping Power Management.
241     </p>
242    
243     <note>
244     You can safely skip this section if you don't like the idea of having another
245     runlevel. However, skipping this step will make the rest a bit trickier to set
246 rane 1.19 up. The next sections assume a runlevel <c>battery</c> exists.
247 swift 1.1 </note>
248    
249     <pre caption="Creating a battery runlevel">
250     # <i>cd /etc/runlevels</i>
251     # <i>cp -a default battery</i>
252     </pre>
253    
254     <p>
255 rane 1.19 Finished. Your new runlevel <c>battery</c> contains everything like
256     <c>default</c>, but there is no automatic switch between both yet. Time to
257 swift 1.1 change it.
258     </p>
259    
260     </body>
261     </section>
262     <section>
263 rane 1.19 <title>Reacting On ACPI Events</title>
264 swift 1.1 <body>
265    
266     <p>
267     Typical ACPI events are closing the lid, changing the power source or pressing
268 swift 1.8 the sleep button. An important event is changing the power source, which should
269 so 1.15 cause a runlevel switch. A small script will take care of it.
270     </p>
271    
272     <p>
273     First you need a script which changes the runlevel to <c>default</c>
274     respectively <c>battery</c> depending on the power source. The script uses the
275     <c>on_ac_power</c> command from <c>sys-power/powermgmt-base</c> - make sure the
276     package is installed on your system.
277     </p>
278    
279     <pre caption="Installing powermgt-base">
280 rane 1.19 # <i>emerge powermgmt-base</i>
281 so 1.15 </pre>
282    
283     <p>
284 rane 1.20 You are now able to determine the power source by executing <c>on_ac_power
285     &amp;&amp; echo AC available || echo Running on batteries</c> in a shell. The
286     script below is responsible for changing runlevels. Save it as
287 so 1.15 <path>/etc/acpi/actions/pmg_switch_runlevel.sh</path>.
288 swift 1.8 </p>
289    
290 neysx 1.12 <pre caption="/etc/acpi/actions/pmg_switch_runlevel.sh">
291 swift 1.8 #!/bin/bash
292    
293 neysx 1.12 <comment># BEGIN configuration</comment>
294 swift 1.8 RUNLEVEL_AC="default"
295     RUNLEVEL_BATTERY="battery"
296 neysx 1.12 <comment># END configuration</comment>
297 swift 1.8
298 swift 1.1
299 neysx 1.12 if [ ! -d "/etc/runlevels/${RUNLEVEL_AC}" ]
300     then
301 nightmorph 1.17 logger "${0}: Runlevel ${RUNLEVEL_AC} does not exist. Aborting."
302     exit 1
303 neysx 1.12 fi
304 swift 1.8
305 neysx 1.12 if [ ! -d "/etc/runlevels/${RUNLEVEL_BATTERY}" ]
306     then
307 nightmorph 1.17 logger "${0}: Runlevel ${RUNLEVEL_BATTERY} does not exist. Aborting."
308     exit 1
309 neysx 1.12 fi
310 swift 1.1
311 neysx 1.12 if on_ac_power
312     then
313 rane 1.19 if [[ "$(&lt;/var/lib/init.d/softlevel)" != "${RUNLEVEL_AC}" ]]
314 nightmorph 1.17 then
315     logger "Switching to ${RUNLEVEL_AC} runlevel"
316     /sbin/rc ${RUNLEVEL_AC}
317     fi
318 rane 1.19 elif [[ "$(&lt;/var/lib/init.d/softlevel)" != "${RUNLEVEL_BATTERY}" ]]
319 neysx 1.12 then
320 nightmorph 1.17 logger "Switching to ${RUNLEVEL_BATTERY} runlevel"
321     /sbin/rc ${RUNLEVEL_BATTERY}
322 neysx 1.12 fi
323 swift 1.8 </pre>
324    
325 so 1.15 <p>
326     Dont forget to run <c>chmod +x /etc/acpi/actions/pmg_switch_runlevel.sh</c> to
327     make the script executable. The last thing that needs to be done is calling the
328     script whenever the power source changes. That's done by catching ACPI events
329     with the help of <c>acpid</c>. First you need to know which events are
330     generated when the power source changes. The events are called
331 rane 1.19 <c>ac_adapter</c> and <c>battery</c> on most laptops, but it might be different
332 so 1.15 on yours.
333     </p>
334    
335     <pre caption="Determining ACPI events for changing the power source">
336 swift 1.32 # <i>tail -f /var/log/messages | grep "received event"</i>
337 so 1.15 </pre>
338    
339     <p>
340 rane 1.20 Run the command above and pull the power cable. You should see something like
341     this:
342 so 1.15 </p>
343    
344     <pre caption="Sample output for power source changes">
345     [Tue Sep 20 17:39:06 2005] received event "ac_adapter AC 00000080 00000000"
346     [Tue Sep 20 17:39:06 2005] received event "battery BAT0 00000080 00000001"
347     </pre>
348    
349     <p>
350 rane 1.19 The interesting part is the quoted string after <c>received event</c>. It will
351 so 1.15 be matched by the event line in the files you are going to create below. Don't
352     worry if your system generates multiple events or always the same. As long as
353     any event is generated, runlevel changing will work.
354     </p>
355    
356 swift 1.8 <pre caption="/etc/acpi/events/pmg_ac_adapter">
357 neysx 1.12 <comment># replace "ac_adapter" below with the event generated on your laptop</comment>
358 so 1.15 <comment># For example, ac_adapter.* will match ac_adapter AC 00000080 00000000</comment>
359 swift 1.8 event=ac_adapter.*
360 neysx 1.12 action=/etc/acpi/actions/pmg_switch_runlevel.sh %e
361 swift 1.8 </pre>
362    
363     <pre caption="/etc/acpi/events/pmg_battery">
364 neysx 1.12 <comment># replace "battery" below with the event generated on your laptop</comment>
365 so 1.15 <comment># For example, battery.* will match battery BAT0 00000080 00000001</comment>
366 swift 1.8 event=battery.*
367 neysx 1.12 action=/etc/acpi/actions/pmg_switch_runlevel.sh %e
368 swift 1.8 </pre>
369 swift 1.1
370 swift 1.8 <p>
371 so 1.15 Finally acpid has to be restarted to recognize the changes.
372 swift 1.8 </p>
373 swift 1.1
374 swift 1.8 <pre caption="Finishing runlevel switching with acpid">
375 rane 1.19 # <i>/etc/init.d/acpid restart</i>
376 swift 1.1 </pre>
377    
378     <p>
379     Give it a try: Plug AC in and out and watch syslog for the "Switching to AC
380 rane 1.20 mode" or "Switching to battery mode" messages. See the <uri
381     link="#doc_chap8">Troubleshooting section</uri> if the script is not able to
382     detect the power source correctly.
383 swift 1.1 </p>
384    
385     <p>
386     Due to the nature of the event mechanism, your laptop will boot into runlevel
387 rane 1.19 <c>default</c> regardless of the AC/battery state. This is fine when running
388 rane 1.20 from AC, but we'd like to boot into the battery runlevel otherwise. One
389     solution would be to add another entry to the boot loader with the parameter
390 so 1.15 <c>softlevel=battery</c>, but it's likely to forget choosing it. A better way
391 rane 1.20 is faking an ACPI event in the end of the boot process and letting
392     <path>pmg_switch_runlevel.sh</path> script decide whether a runlevel change is
393     necessary. Open <path>/etc/conf.d/local.start</path> in your favourite editor
394     and add these lines:
395 swift 1.1 </p>
396    
397 so 1.15 <pre caption="Runlevel adjustment at boot time by editing local.start">
398 swift 1.1 <comment># Fake acpi event to switch runlevel if running on batteries</comment>
399 neysx 1.12 /etc/acpi/actions/pmg_switch_runlevel.sh "battery/battery"
400 swift 1.1 </pre>
401    
402     <p>
403 rane 1.20 Prepared like this you can activate Power Management policies for individual
404 swift 1.1 devices.
405     </p>
406    
407     </body>
408     </section>
409     </chapter>
410    
411     <chapter>
412     <title>CPU Power Management</title>
413     <section>
414 nightmorph 1.17 <body>
415    
416     <p>
417     Mobile processors can operate at different frequencies. Some allow changing
418     voltage as well. Most of the time your CPU doesn't need to run at full speed
419     and scaling it down will save much energy - often without any performance
420     decrease.
421     </p>
422    
423     </body>
424     </section>
425     <section>
426 rane 1.19 <title>Some Technical Terms</title>
427 swift 1.8 <body>
428    
429     <p>
430     CPU frequency scaling brings up some technical terms that might be unknown to
431     you. Here's a quick introduction.
432     </p>
433    
434     <p>
435 so 1.15 First of all, the kernel has to be able to change the processor's frequency.
436 rane 1.19 The <b>CPUfreq processor driver</b> knows the commands to do it on your CPU.
437 rane 1.20 Thus it's important to choose the right one in your kernel. You should already
438     have done it above. Once the kernel knows how to change frequencies, it has to
439     know which frequency it should set. This is done according to the <b>policy</b>
440     which consists of a <b>CPUfreq policy</b> and a <b>governor</b>. A CPUfreq
441     policy are just two numbers which define a range the frequency has to stay
442     between - minimal and maximal frequency. The governor now decides which of the
443     available frequencies in between minimal and maximal frequency to choose. For
444     example, the <b>powersave governor</b> always chooses the lowest frequency
445     available, the <b>performance governor</b> the highest one. The <b>userspace
446     governor</b> makes no decision but chooses whatever the user (or a program in
447     userspace) wants - which means it reads the frequency from
448 swift 1.8 <path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed</path>.
449     </p>
450    
451     <p>
452     This doesn't sound like dynamic frequency changes yet and in fact it isn't.
453 rane 1.20 Dynamics however can be accomplished with various approaches. For example, the
454     <b>ondemand governor</b> makes its decisions depending on the current CPU load.
455     The same is done by various userland tools like <c>cpudyn</c>, <c>cpufreqd</c>,
456     <c>powernowd</c> and many more. ACPI events can be used to enable or disable
457     dynamic frequency changes depending on power source.
458 swift 1.8 </p>
459    
460     </body>
461     </section>
462     <section>
463 nightmorph 1.41 <title>Setting The Frequency</title>
464 swift 1.1 <body>
465    
466     <p>
467     Decreasing CPU speed and voltage has two advantages: On the one hand less
468     energy is consumed, on the other hand there is thermal improvement as your
469     system doesn't get as hot as running on full speed. The main disadvantage is
470     obviously the loss of performance. Decreasing processor speed is a trade off
471     between performance loss and energy saving.
472     </p>
473    
474     <note>
475     Not every laptop supports frequency scaling. If unsure, have a look at the list
476 rane 1.19 of supported processors in the <uri link="#doc_chap8">Troubleshooting</uri>
477     section to verify yours is supported.
478 swift 1.1 </note>
479    
480     <p>
481 neysx 1.12 It's time to test whether CPU frequency changing works. Let's install another
482 nightmorph 1.41 tool: <c>sys-power/cpufrequtils</c>.
483 swift 1.1 </p>
484    
485 neysx 1.12 <pre caption="Checking CPU frequency">
486     # <i>emerge cpufrequtils</i>
487     # <i>cpufreq-info</i>
488 swift 1.1 </pre>
489    
490     <p>
491 neysx 1.12 Here is an example output:
492 swift 1.1 </p>
493    
494 neysx 1.12 <pre caption="Sample output from cpufreq-info">
495 so 1.15 cpufrequtils 0.3: cpufreq-info (C) Dominik Brodowski 2004
496 neysx 1.12 Report errors and bugs to linux@brodo.de, please.
497     analyzing CPU 0:
498     driver: centrino
499     CPUs which need to switch frequency at the same time: 0
500     hardware limits: 600 MHz - 1.40 GHz
501     available frequency steps: 600 MHz, 800 MHz, 1000 MHz, 1.20 GHz, 1.40 GHz
502 so 1.15 available cpufreq governors: conservative, ondemand, powersave, userspace, performance
503 neysx 1.12 current policy: frequency should be within 924 MHz and 1.40 GHz.
504     The governor "performance" may decide which speed to use
505     within this range.
506 so 1.15 current CPU frequency is 1.40 GHz.
507 neysx 1.12 </pre>
508    
509 swift 1.1 <p>
510 neysx 1.12 Now play around with <c>cpufreq-set</c> to make sure frequency switching works.
511     Run <c>cpufreq-set -g ondemand</c> for example to activate the ondemand
512     governor and verify the change with <c>cpufreq-info</c>. If it doesn't work as
513 rane 1.20 expected, you might find help in the <uri link="#doc_chap8">Troubleshooting
514     section</uri> in the end of this guide.
515 swift 1.1 </p>
516    
517 nightmorph 1.41 <p>
518     <c>cpufrequtils</c> can operate in an automatic mode (when you use the
519     <b>ondemand</b> governor), you can also switch to the <b>userspace</b> governor
520     if you want to manually set a specific speed. You can also statically set your
521     CPU to its highest or lowest frequency by using the <b>performance</b>
522     and <b>powersave</b> governors, respectively.
523     </p>
524    
525     <pre caption="Changing CPU speeds">
526     <comment>(Set the highest available frequency)</comment>
527     # <i>cpufreq-set -g performance</i>
528     <comment>(Set the lowest available frequency)</comment>
529     # <i>cpufreq-set -g powersave</i>
530     <comment>(Set a specific frequency)</comment>
531     # <i>cpufreq-set -g userspace</i>
532     # <i>cpufreq-set -f 2.00ghz</i>
533     </pre>
534    
535 swift 1.1 </body>
536     </section>
537     <section>
538 nightmorph 1.41 <title>Other CPU Speed Utilities</title>
539 swift 1.1 <body>
540    
541     <p>
542 nightmorph 1.41 While <c>cpufrequtils</c> may be the best all-around program, there are some
543     other choices available in Portage. The following table gives a quick overview
544     of available CPU speed utilities. It's roughly separated in three categories
545     <b>kernel</b> for approaches that only need kernel support, <b>daemon</b> for
546     programs that run in the background and <b>graphical</b> for programs that
547     provide a GUI for easy configuration and changes.
548 swift 1.1 </p>
549    
550     <table>
551     <tr>
552     <th>Name</th>
553 swift 1.8 <th>Category</th>
554     <th>Switch decision</th>
555     <th>Kernel governors</th>
556     <th>Further governors</th>
557     <th>Comments</th>
558     </tr>
559     <tr>
560     <ti>'ondemand' governor</ti>
561     <ti>Kernel</ti>
562     <ti>CPU load</ti>
563     <ti>N.A.</ti>
564     <ti>N.A.</ti>
565     <ti>
566 so 1.15 Chooses maximal frequency on CPU load and slowly steps down when the CPU is
567     idle. Further tuning through files in
568 swift 1.8 <path>/sys/devices/system/cpu/cpu0/cpufreq/ondemand/</path>. Still requires
569     userland tools (programs, scripts) if governor switching or similar is
570     desired.
571     </ti>
572 swift 1.1 </tr>
573     <tr>
574 so 1.15 <ti>'conservative' governor</ti>
575     <ti>Kernel</ti>
576     <ti>CPU load</ti>
577     <ti>N.A.</ti>
578     <ti>N.A.</ti>
579     <ti>
580 neysx 1.16 Unlike the ondemand governor, conversative doesn't jump to maximum
581     frequency when CPU load is high, but increases the frequency step by step.
582     Further tuning through files in
583     <path>/sys/devices/system/cpu/cpu0/cpufreq/ondemand/</path>. Still requires
584     userland tools (programs, scripts) if governor switching or similar is
585     desired.
586 so 1.15 </ti>
587     </tr>
588     <tr>
589 swift 1.1 <ti><uri link="http://mnm.uib.es/~gallir/cpudyn/">cpudyn</uri></ti>
590 swift 1.8 <ti>Daemon</ti>
591     <ti>CPU load</ti>
592 neysx 1.12 <ti>Performance, powersave</ti>
593 swift 1.8 <ti>Dynamic</ti>
594     <ti>
595     Also supports disk standby - notice however that <e>laptop mode</e> in most
596     cases will do a better job.
597     </ti>
598 swift 1.1 </tr>
599     <tr>
600 swift 1.8 <ti><uri link="http://sourceforge.net/projects/cpufreqd/">cpufreqd</uri></ti>
601     <ti>Daemon</ti>
602 nightmorph 1.17 <ti>Battery state, CPU load, temperature, running programs and more</ti>
603 swift 1.8 <ti>All available</ti>
604     <ti>None</ti>
605     <ti>
606 nightmorph 1.17 Sophisticated (but somewhat complicated) setup. Extendible through plugins
607     like sensor monitoring (lm_sensors) or coordinating some NVidia based
608     graphics card memory and core. Cpufreqd is SMP aware and can optionally be
609     controlled manually at runtime.
610 swift 1.8 </ti>
611     </tr>
612     <tr>
613     <ti>
614     <uri link="http://www.deater.net/john/powernowd.html">powernowd</uri>
615     </ti>
616     <ti>Daemon</ti>
617     <ti>CPU load</ti>
618     <ti>None</ti>
619     <ti>Passive, sine, aggressive</ti>
620     <ti>
621     Supports SMP.
622     </ti>
623 swift 1.1 </tr>
624     <tr>
625 nightmorph 1.31 <ti>
626     <uri
627     link="http://projects.simpledesigns.com.pl/project/ncpufreqd/">ncpufreqd</uri>
628     </ti>
629 so 1.15 <ti>Daemon</ti>
630     <ti>Temperature</ti>
631     <ti>None</ti>
632     <ti>Powersave, performance</ti>
633     <ti>
634     Toggles the used governor between performance and powersave depending on
635     system temperature. Very useful on laptops with notorious heat problems.
636     </ti>
637     </tr>
638     <tr>
639 swift 1.1 <ti><uri link="http://www.goop.org/~jeremy/speedfreq/">speedfreq</uri></ti>
640 swift 1.8 <ti>Daemon</ti>
641     <ti>CPU load</ti>
642     <ti>None</ti>
643     <ti>Dynamic, powersave, performance, fixed speed</ti>
644     <ti>
645 so 1.15 Easy to configure with a nice client/server interface. Requires a 2.6
646     kernel. Unmaintained, broken and thus removed from Portage. Please switch
647     to cpufreqd if you're still using it.
648 swift 1.8 </ti>
649     </tr>
650     <tr>
651     <ti><uri link="http://cpuspeedy.sourceforge.net/">gtk-cpuspeedy</uri></ti>
652     <ti>Graphical</ti>
653     <ti>None</ti>
654     <ti>None</ti>
655     <ti>None</ti>
656 swift 1.1 <ti>
657 swift 1.8 Gnome application, a graphical tool to set CPU frequency manually. It does
658 neysx 1.12 not offer any automation.
659 swift 1.1 </ti>
660     </tr>
661     <tr>
662 swift 1.8 <ti>klaptopdaemon</ti>
663     <ti>Graphical</ti>
664     <ti>Battery state</ti>
665     <ti>All available</ti>
666     <ti>None</ti>
667     <ti>
668     KDE only, 'ondemand' governor required for dynamic frequency scaling.
669     </ti>
670 swift 1.1 </tr>
671     </table>
672    
673     <p>
674 so 1.15 While adjusting the frequency to the current load looks simple at a first
675     glance, it's not such a trivial task. A bad algorithm can cause switching
676     between two frequencies all the time or wasting energy when setting frequency
677 rane 1.20 to an unnecessary high level.
678 swift 1.1 </p>
679    
680     <p>
681 neysx 1.12 Which one to choose? If you have no idea about it, try <c>cpufreqd</c>:
682 swift 1.1 </p>
683    
684     <pre caption="Installing cpufreqd">
685     # <i>emerge cpufreqd</i>
686     </pre>
687    
688     <p>
689 neysx 1.12 <c>cpufreqd</c> can be configured by editing <path>/etc/cpufreqd.conf</path>.
690     The default one that ships with cpufreqd may look a bit confusing. I recommend
691 nightmorph 1.22 replacing it with the one from former Gentoo developer Henrik Brix Andersen
692     (see below). Please notice that you need cpufreqd-2.0.0 or later. Earlier
693     versions have a different syntax for the config file.
694 swift 1.1 </p>
695    
696 nightmorph 1.17 <pre caption="/etc/cpufreqd.conf (cpufreqd-2.0.0 and later)">
697 swift 1.1 [General]
698     pidfile=/var/run/cpufreqd.pid
699 nightmorph 1.17 poll_interval=3
700     enable_plugins=acpi_ac, acpi_battery
701 nightmorph 1.18 enable_remote=1
702     remote_group=wheel
703 neysx 1.12 verbosity=5
704 nightmorph 1.17 [/General]
705 swift 1.1
706     [Profile]
707 neysx 1.12 name=ondemand
708     minfreq=0%
709     maxfreq=100%
710     policy=ondemand
711 nightmorph 1.17 [/Profile]
712 swift 1.1
713     [Profile]
714 so 1.15 name=conservative
715     minfreq=0%
716     maxfreq=100%
717     policy=conservative
718 nightmorph 1.17 [/Profile]
719 so 1.15
720     [Profile]
721 neysx 1.12 name=powersave
722     minfreq=0%
723     maxfreq=100%
724 swift 1.1 policy=powersave
725 nightmorph 1.17 [/Profile]
726 swift 1.1
727     [Profile]
728 neysx 1.12 name=performance
729     minfreq=0%
730     maxfreq=100%
731     policy=performance
732 nightmorph 1.17 [/Profile]
733 swift 1.1
734     [Rule]
735 neysx 1.12 name=battery
736     ac=off
737 so 1.15 profile=conservative
738 nightmorph 1.17 [/Rule]
739 swift 1.1
740     [Rule]
741 neysx 1.12 name=battery_low
742 swift 1.1 ac=off
743 neysx 1.12 battery_interval=0-10
744     profile=powersave
745 nightmorph 1.17 [/Rule]
746 swift 1.1
747     [Rule]
748 neysx 1.12 name=ac
749     ac=on
750 so 1.15 profile=ondemand
751 nightmorph 1.17 [/Rule]
752 neysx 1.12 </pre>
753    
754     <p>
755 rane 1.19 Now you can start the cpufreqd daemon. Add it to the <c>default</c> and
756     <c>battery</c> runlevel as well.
757 swift 1.1 </p>
758    
759 neysx 1.12 <pre caption="Starting cpufreqd">
760     # <i>rc-update add cpufreqd default battery</i>
761 nightmorph 1.41 # <i>/etc/init.d/cpufreqd start</i>
762 neysx 1.12 </pre>
763    
764 nightmorph 1.17 <p>
765     Sometimes it can be desirable to select another policy than the daemon chooses,
766     for example when battery power is low, but you know that AC will be available
767 rane 1.20 soon. In that case you can turn on cpufreqd's manual mode with <c>cpufreqd-set
768     manual</c> and select one of your configured policies (as listed by
769     <c>cpufreqd-get</c>). You can leave manual mode by executing <c>cpufreqd-set
770     dynamic</c>.
771 nightmorph 1.17 </p>
772    
773 neysx 1.12 <warn>
774     Do not run more than one of the above programs at the same time. It may cause
775     confusion like switching between two frequencies all the time.
776     </warn>
777    
778 swift 1.8 </body>
779     </section>
780     <section>
781     <title>Verifying the result</title>
782     <body>
783    
784 swift 1.1 <p>
785     The last thing to check is that your new policies do a good job. An easy way to
786 swift 1.8 do so is monitoring CPU speed while working with your laptop:
787 swift 1.1 </p>
788    
789     <pre caption="Monitoring CPU speed">
790 yoswink 1.13 # <i>watch grep \"cpu MHz\" /proc/cpuinfo</i>
791 swift 1.1 </pre>
792    
793     <p>
794 rane 1.20 If <path>/proc/cpuinfo</path> doesn't get updated (see <uri
795 swift 1.32 link="#doc_chap8">Troubleshooting</uri>), monitor the CPU frequency with
796     <c>sys-apps/x86info</c>:
797 swift 1.1 </p>
798    
799     <pre caption="Alternative CPU speed monitoring">
800 neysx 1.12 # <i>watch x86info -mhz</i>
801 swift 1.1 </pre>
802    
803     <p>
804     Depending on your setup, CPU speed should increase on heavy load, decrease on
805 rane 1.19 no activity or just stay at the same level. When using <c>cpufreqd</c> and
806 rane 1.20 verbosity set to 5 or higher in <path>cpufreqd.conf</path> you'll get
807     additional information about what's happening reported to <c>syslog</c>.
808 swift 1.1 </p>
809    
810     </body>
811     </section>
812     </chapter>
813    
814     <chapter>
815     <title>LCD Power Management</title>
816     <section>
817     <body>
818    
819     <p>
820 rane 1.20 As you can see in <uri link="#doc_chap1_fig1">figure 1.1</uri>, the LCD
821     display consumes the biggest part of energy (might not be the case for
822     non-mobile CPU's). Thus it's quite important not only to shut the display off
823     when not needed, but also to reduce it's backlight if possible. Most laptops
824     offer the possibility to control the backlight dimming.
825 swift 1.1 </p>
826    
827 nightmorph 1.17 </body>
828     </section>
829     <section>
830     <title>Standby settings</title>
831     <body>
832    
833 swift 1.1 <p>
834 nightmorph 1.17 The first thing to check is the standby/suspend/off timings of the display. As
835     this depends heavily on your windowmanager, I'll let you figure it out
836 rane 1.20 yourself. Just two common places: Blanking the terminal can be done with
837 nightmorph 1.17 <c>setterm -blank &lt;number-of-minutesM&gt;</c>, <c>setterm -powersave on</c>
838     and <c>setterm -powerdown &lt;number-of-minutesM&gt;</c>. For X.org, modify
839     <path>/etc/X11/xorg.conf</path> similar to this:
840 swift 1.1 </p>
841    
842 nightmorph 1.35 <pre caption="LCD suspend settings in X.org">
843     Section "ServerFlags"
844     Option "blank time" "5" <comment># Blank the screen after 5 minutes (Fake)</comment>
845     Option "standby time" "10" <comment># Turn off screen after 10 minutes (DPMS)</comment>
846     Option "suspend time" "20" <comment># Full suspend after 20 minutes</comment>
847     Option "off time" "30" <comment># Turn off after half an hour</comment>
848 swift 1.1 [...]
849     EndSection
850    
851     [...]
852    
853     Section "Monitor"
854     Identifier [...]
855 nightmorph 1.35 Option "DPMS"
856 swift 1.1 [...]
857     EndSection
858     </pre>
859    
860 nightmorph 1.17 </body>
861     </section>
862     <section>
863     <title>Backlight dimming</title>
864     <body>
865    
866 swift 1.1 <p>
867     Probably more important is the backlight dimming. If you have access to the
868     dimming settings via a tool, write a small script that dims the backlight in
869 rane 1.19 battery mode and place it in your <c>battery</c> runlevel. The following script
870 nightmorph 1.17 should work on most IBM Thinkpads and Toshiba laptops. You've got to enable the
871 rane 1.20 appropriate option in your kernel (IBM Thinkpads only). For Toshiba laptops,
872 nightmorph 1.35 install <c>sys-power/acpitool</c> and skip configuration of <c>thinkpad_acpi</c>
873     (formerly called <c>ibm_acpi</c>) as described below.
874 neysx 1.12 </p>
875    
876     <warn>
877 swift 1.36 Support for setting brightness is marked experimental in thinkpad_acpi. It
878     accesses hardware directly and may cause severe harm to your system. Please
879     read the <uri link="http://ibm-acpi.sourceforge.net/">thinkpad_acpi
880     website</uri>
881 neysx 1.12 </warn>
882    
883     <p>
884 swift 1.36 To be able to set the brightness level, the thinkpad_acpi module has to be
885     loaded with the experimental parameter.
886 neysx 1.12 </p>
887    
888 nightmorph 1.35 <pre caption="automatically loading the thinkpad_acpi module">
889 neysx 1.12 <comment>(Please read the warnings above before doing this!)</comment>
890 nightmorph 1.37 # <i>echo "options thinkpad_acpi experimental=1" >> /etc/modprobe.d/thinkpad_acpi</i>
891     # <i>update-modules</i>
892 nightmorph 1.35 # <i>echo thinkpad_acpi >> /etc/modules.autoload.d/kernel-2.6</i>
893     # <i>modprobe thinkpad_acpi</i>
894 neysx 1.12 </pre>
895    
896     <p>
897     This should work without error messages and a file
898     <path>/proc/acpi/ibm/brightness</path> should be created after loading the
899 rane 1.20 module. An init script will take care of choosing the brightness according to
900     the power source.
901 neysx 1.12 </p>
902    
903     <pre caption="/etc/conf.d/lcd-brightness">
904     <comment># See /proc/acpi/ibm/brightness for available values</comment>
905 nightmorph 1.35 <comment># Please read /usr/src/linux/Documentation/thinkpad-acpi.txt</comment>
906 neysx 1.12
907 nightmorph 1.23 <comment># brightness level in ac mode. Default is 7.</comment>
908 neysx 1.12 BRIGHTNESS_AC=7
909    
910     <comment># brightness level in battery mode. Default is 4.</comment>
911     BRIGHTNESS_BATTERY=4
912     </pre>
913    
914     <pre caption="/etc/init.d/lcd-brightness">
915     #!/sbin/runscript
916    
917     set_brightness() {
918     if on_ac_power
919     then
920     LEVEL=${BRIGHTNESS_AC:-7}
921     else
922     LEVEL=${BRIGHTNESS_BATTERY:-4}
923     fi
924    
925     if [ -f /proc/acpi/ibm/brightness ]
926     then
927     ebegin "Setting LCD brightness"
928     echo "level ${LEVEL}" > /proc/acpi/ibm/brightness
929     eend $?
930 nightmorph 1.17 elif [[ -e /usr/bin/acpitool &amp;&amp; -n $(acpitool -T | grep "LCD brightness") ]]
931     then
932     ebegin "Setting LCD brightness"
933     acpitool -l $LEVEL >/dev/null || ewarn "Unable to set lcd brightness"
934     eend $?
935 neysx 1.12 else
936     ewarn "Setting LCD brightness is not supported."
937 nightmorph 1.35 ewarn "For IBM Thinkpads, check that thinkpad_acpi is loaded into the kernel"
938 nightmorph 1.23 ewarn "For Toshiba laptops, you've got to install sys-power/acpitool"
939 neysx 1.12 fi
940     }
941    
942     start() {
943     set_brightness
944     }
945    
946     stop () {
947     set_brightness
948     }
949     </pre>
950    
951     <p>
952     When done, make sure brightness is adjusted automatically by adding it to the
953     battery runlevel.
954 swift 1.1 </p>
955    
956 neysx 1.12 <pre caption="Enabling automatic brightness adjustment">
957 rane 1.19 # <i>chmod +x /etc/init.d/lcd-brightness</i>
958     # <i>rc-update add lcd-brightness battery</i>
959     # <i>rc</i>
960 neysx 1.12 </pre>
961    
962 swift 1.1 </body>
963     </section>
964     </chapter>
965    
966     <chapter>
967     <title>Disk Power Management</title>
968     <section>
969 nightmorph 1.17 <body>
970 rane 1.19
971 nightmorph 1.17 <p>
972     Hard disks consume less energy in sleep mode. Therefore it makes sense to
973     activate power saving features whenever the hard disk is not used for a certain
974     amount of time. I'll show you two alternative possibilities to do it. First,
975     laptop-mode will save most energy due to several measures which prevent or at
976     least delay write accesses. The drawback is that due to the delayed write
977     accesses a power outage or kernel crash will be more dangerous for data loss.
978     If you don't like this, you have to make sure that there are no processes which
979     write to your hard disk frequently. Afterwards you can enable power saving
980 rane 1.19 features of your hard disk with <c>hdparm</c> as the second alternative.
981 nightmorph 1.17 </p>
982    
983     </body>
984     </section>
985     <section>
986     <title>Increasing idle time - laptop-mode</title>
987 swift 1.1 <body>
988    
989     <p>
990 nightmorph 1.27 Recent 2.6 kernels include the so-called <c>laptop-mode</c>. When activated,
991     dirty buffers are written to disk on read calls or after 10 minutes (instead of
992     30 seconds). This minimizes the time the hard disk needs to be spun up.
993 swift 1.1 </p>
994    
995 nightmorph 1.17 <pre caption="Automated start of laptop-mode">
996     # <i>emerge laptop-mode-tools</i>
997     </pre>
998 swift 1.1
999 nightmorph 1.17 <p>
1000     <c>laptop-mode-tools</c> has its configuration file in
1001     <path>/etc/laptop-mode/laptop-mode.conf</path>. Adjust it the way you like it,
1002     it's well commented. Run <c>rc-update add laptop_mode battery</c> to start it
1003     automatically.
1004     </p>
1005    
1006     <p>
1007     Recent versions (1.11 and later) of laptop-mode-tools include a new tool
1008     <c>lm-profiler</c>. It will monitor your system's disk usage and running
1009     network services and suggests to disable unneeded ones. You can either disable
1010     them through laptop-mode-tools builtin runlevel support (which will be reverted
1011 rane 1.19 by Gentoo's <c>/sbin/rc</c>) or use your <c>default</c>/<c>battery</c>
1012 nightmorph 1.17 runlevels (recommended).
1013     </p>
1014    
1015     <pre caption="Sample output from running lm-profiler">
1016 rane 1.19 # <i>lm-profiler</i>
1017 nightmorph 1.17 Profiling session started.
1018     Time remaining: 600 seconds
1019     [4296896.602000] amarokapp
1020     Time remaining: 599 seconds
1021     [4296897.714000] sort
1022     [4296897.970000] mv
1023     Time remaining: 598 seconds
1024     Time remaining: 597 seconds
1025     [4296900.482000] reiserfs/0
1026     </pre>
1027    
1028     <p>
1029     After profiling your system for ten minutes, lm-profiler will present a list of
1030     services which might have caused disk accesses during that time.
1031     </p>
1032    
1033     <pre caption="lm-profiler suggests to disable some services">
1034     Program: "atd"
1035     Reason: standard recommendation (program may not be running)
1036     Init script: /etc/init.d/atd (GUESSED)
1037    
1038 rane 1.19 Do you want to disable this service in battery mode? [y/N]: <i>n</i>
1039 swift 1.1 </pre>
1040    
1041     <p>
1042 nightmorph 1.17 To disable atd as suggested in the example above, you would run <c>rc-update
1043     del atd battery</c>. Be careful not to disable services that are needed for
1044 rane 1.20 your system to run properly - <c>lm-profiler</c> is likely to generate some
1045     false positives. Do not disable a service if you are unsure whether it's
1046     needed.
1047 nightmorph 1.17 </p>
1048    
1049     </body>
1050     </section>
1051     <section>
1052 rane 1.19 <title>Limiting Write Accesses</title>
1053 nightmorph 1.17 <body>
1054    
1055     <p>
1056     If you don't want to use laptop-mode, you must take special care to disable
1057     services that write to your disk frequently - <c>syslogd</c> is a good
1058     candidate, for example. You probably don't want to shut it down completely, but
1059     it's possible to modify the config file so that "unnecessary" things don't get
1060 rane 1.20 logged and thus don't create disk traffic. <c>Cups</c> writes to disk
1061     periodically, so consider shutting it down and only enable it manually when
1062     needed.
1063 nightmorph 1.17 </p>
1064    
1065     <pre caption="Disabling cups in battery mode">
1066     # <i>rc-update del cupsd battery</i>
1067     </pre>
1068    
1069     <p>
1070     You can also use <c>lm-profiler</c> from laptop-mode-tools (see above) to find
1071     services to disable. Once you eliminated all of them, go on with configuring
1072     hdparm.
1073     </p>
1074    
1075     </body>
1076     </section>
1077     <section>
1078     <title>hdparm</title>
1079     <body>
1080    
1081     <p>
1082 nightmorph 1.28 The second possibility is using <c>hdparm</c>. Skip this if
1083     you are using laptop-mode. Otherwise, edit <path>/etc/conf.d/hdparm</path> and
1084     add the following values to your drive entries. This example assumes your hard
1085     drive is called <b>hda</b>:
1086 swift 1.1 </p>
1087    
1088 nightmorph 1.28 <pre caption="Using /etc/conf.d/hdparm for disk standby">
1089     hda_args="-q -S12"
1090     </pre>
1091 neysx 1.12
1092 nightmorph 1.28 <p>
1093     This will activate power management for your hard drive. If you ever want to
1094     deactivate power management, you can edit <path>/etc/conf.d/hdparm</path> and
1095     change the values to <c>-q -S0</c>, or just run <c>hdparm -q -S0 /dev/hda</c>.
1096     </p>
1097 swift 1.1
1098     <p>
1099 nightmorph 1.28 See <c>man hdparm</c> for the options. Though you can always start <c>hdparm</c>
1100     manually when you are on battery power by running <c>/etc/init.d/hdparm
1101     start</c>, it's much easier to automate its startup and shutdown. To do so, add
1102     <c>hdparm</c> to the battery runlevel so that it will automatically enable power
1103     management.
1104 swift 1.1 </p>
1105    
1106     <pre caption="Automate disk standby settings">
1107 nightmorph 1.28 # <i>rc-update add hdparm battery</i>
1108 swift 1.1 </pre>
1109    
1110     <impo>
1111     Be careful with sleep/spin down settings of your hard drive. Setting it to
1112     small values might wear out your drive and lose warranty.
1113     </impo>
1114    
1115     </body>
1116     </section>
1117     <section>
1118     <title>Other tricks</title>
1119     <body>
1120    
1121     <p>
1122     Another possibility is to deactivate swap in battery mode. Before writing a
1123     swapon/swapoff switcher, make sure there is enough RAM and swap isn't used
1124     heavily, otherwise you'll be in big problems.
1125     </p>
1126    
1127     <p>
1128     If you don't want to use laptop-mode, it's still possible to minimize disk
1129 rane 1.19 access by mounting certain directories as <c>tmpfs</c> - write accesses are not
1130 swift 1.1 stored on a disk, but in main memory and get lost with unmounting. Often it's
1131     useful to mount <path>/tmp</path> like this - you don't have to pay special
1132     attention as it gets cleared on every reboot regardless whether it was mounted
1133     on disk or in RAM. Just make sure you have enough RAM and no program (like a
1134     download client or compress utility) needs extraordinary much space in
1135     <path>/tmp</path>. To activate this, enable tmpfs support in your kernel and
1136     add a line to <path>/etc/fstab</path> like this:
1137     </p>
1138    
1139     <pre caption="Editing /etc/fstab to make /tmp even more volatile">
1140     none /tmp tmpfs size=32m 0 0
1141     </pre>
1142    
1143     <warn>
1144     Pay attention to the size parameter and modify it for your system. If you're
1145 rane 1.21 unsure, don't try this at all, it can become a performance bottleneck easily. In
1146 swift 1.1 case you want to mount <path>/var/log</path> like this, make sure to merge the
1147     log files to disk before unmounting. They are essential. Don't attempt to mount
1148 rane 1.19 <path>/var/tmp</path> like this. Portage uses it for compiling...
1149 swift 1.1 </warn>
1150    
1151     </body>
1152     </section>
1153     </chapter>
1154    
1155     <chapter>
1156 rane 1.19 <title>Power Management For Other Devices</title>
1157 swift 1.1 <section>
1158 rane 1.19 <title>Graphics Cards</title>
1159 so 1.15 <body>
1160    
1161     <p>
1162     In case you own an ATI graphics card supporting PowerPlay (dynamic clock
1163 nightmorph 1.25 scaling for the graphics processing unit GPU), you can activate this
1164 rane 1.20 feature in X.org. Open <path>/etc/X11/xorg.conf</path> and add (or enable) the
1165     <c>DynamicClocks</c> option in the Device section. Please notice that this
1166     feature will lead to crashes on some systems.
1167 so 1.15 </p>
1168    
1169     <pre caption="Enabling ATI PowerPlay support in X.org">
1170     Section "Device"
1171     [...]
1172     Option "DynamicClocks" "on"
1173     EndSection
1174     </pre>
1175    
1176     </body>
1177     </section>
1178     <section>
1179 swift 1.1 <title>Wireless Power Management</title>
1180     <body>
1181    
1182     <p>
1183 nightmorph 1.17 Wireless LAN cards consume quite a bit of energy. Put them in Power Management
1184 nightmorph 1.28 mode just like your hard drives.
1185 swift 1.1 </p>
1186    
1187 nightmorph 1.17 <note>
1188     This script assumes your wireless interface is called <c>wlan0</c>; replace
1189     this with the actual name of your interface.
1190     </note>
1191    
1192 nightmorph 1.28 <p>
1193 nightmorph 1.29 Add the following option to <path>/etc/conf.d/net</path> to automatically enable
1194 nightmorph 1.28 power management for your wireless card:
1195     </p>
1196 swift 1.1
1197 nightmorph 1.28 <pre caption="Automated WLAN Power Management">
1198     iwconfig_wlan0="power on"
1199 swift 1.1 </pre>
1200    
1201     <p>
1202 nightmorph 1.28 See <c>man iwconfig</c> for details and more options like the period between
1203     wakeups or timeout settings. If your driver and access point support changing
1204     the beacon time, this is a good starting point to save even more energy.
1205 swift 1.1 </p>
1206    
1207     </body>
1208     </section>
1209     <section>
1210     <title>USB Power Management</title>
1211     <body>
1212    
1213     <p>
1214     There are two problems with USB devices regarding energy consumption: First,
1215     devices like USB mice, digital cameras or USB sticks consume energy while
1216     plugged in. You cannot avoid this (nevertheless remove them in case they're not
1217     needed). Second, when there are USB devices plugged in, the USB host controller
1218     periodically accesses the bus which in turn prevents the CPU from going into
1219 rane 1.20 sleep mode. The kernel offers an experimental option to enable suspension of
1220 so 1.15 USB devices through driver calls or one of the <path>power/state</path> files
1221     in <path>/sys</path>.
1222 swift 1.1 </p>
1223    
1224 so 1.15 <pre caption="Enabling USB suspend support in the kernel">
1225     Device Drivers
1226     USB support
1227     [*] Support for Host-side USB
1228     [*] USB suspend/resume (EXPERIMENTAL)
1229     </pre>
1230    
1231 swift 1.1 </body>
1232     </section>
1233     </chapter>
1234    
1235     <chapter>
1236 rane 1.19 <title>Sleep States: sleep, standby, and suspend to disk</title>
1237 swift 1.1 <section>
1238     <body>
1239    
1240     <p>
1241     ACPI defines different sleep states. The more important ones are
1242     </p>
1243    
1244 rane 1.20 <ul>
1245 swift 1.1 <li>S1 aka Standby</li>
1246     <li>S3 aka Suspend to RAM aka Sleep</li>
1247     <li>S4 aka Suspend to Disk aka Hibernate</li>
1248     </ul>
1249    
1250     <p>
1251     They can be called whenever the system is not in use, but a shutdown is not
1252     wanted due to the long boot time.
1253     </p>
1254    
1255     </body>
1256     </section>
1257     <section>
1258 so 1.15 <title>Sleep (S3)</title>
1259 swift 1.1 <body>
1260    
1261     <p>
1262 so 1.15 The ACPI support for these sleep states is marked experimental for good reason.
1263     APM sleep states seem to be more stable, however you can't use APM and ACPI
1264     together.
1265     </p>
1266    
1267     <pre caption="Kernel configuration for the various suspend types">
1268     Power Management Options ---&gt;
1269     [*] Power Management support
1270 nightmorph 1.40 [*] Suspend to RAM and standby
1271 so 1.15 </pre>
1272    
1273     <p>
1274 nightmorph 1.17 Once your kernel is properly configured, you can use the
1275 so 1.15 <c>hibernate-script</c> to activate suspend or sleep mode. Let's install that
1276     first.
1277     </p>
1278    
1279     <pre caption="Installing the hibernate-script">
1280 rane 1.19 # <i>emerge hibernate-script</i>
1281 so 1.15 </pre>
1282    
1283     <p>
1284 nightmorph 1.25 Some configuration has to be done in <path>/etc/hibernate</path>. The default
1285 nightmorph 1.24 package introduces a few configuration files for each sleep state. Options that
1286     are common to all suspend methods are placed in <path>common.conf</path>; make
1287     sure this file is properly set up for your system.
1288 so 1.15 </p>
1289    
1290     <p>
1291 nightmorph 1.24 To configure sleep, edit <path>sysfs-ram.conf</path> in
1292     <path>/etc/hibernate</path>. <c>UseSysfsPowerState mem</c> is already setup
1293 nightmorph 1.25 correctly, but if you need to make further changes to this particular sleep
1294     state (or any other sleep state) you should add them to
1295 nightmorph 1.24 <path>/etc/hibernate/hibernate.conf</path>. The comments and option names will
1296     guide you. If you use nfs or samba shares over the network, make sure to
1297     shutdown the appropriate init scripts to avoid timeouts.
1298 so 1.15 </p>
1299    
1300 nightmorph 1.24 <note>
1301     For more information on setting up sleep states, read <c>man
1302     hibernate.conf</c>.
1303     </note>
1304    
1305 so 1.15 <p>
1306     Ready? Now is the last chance to backup any data you want to keep after
1307     executing the next command. Notice that you probably have to hit a special key
1308 rane 1.19 like <c>Fn</c> to resume from sleep.
1309 so 1.15 </p>
1310    
1311     <pre caption="Calling sleep">
1312 rane 1.19 # <i>hibernate-ram</i>
1313 so 1.15 </pre>
1314    
1315     <p>
1316 rane 1.20 If you're still reading, it seems to work. You can also setup standby (S1) in a
1317 nightmorph 1.24 similar way by editing <path>sysfs-ram.conf</path> and changing
1318     "UseSysfsPowerState mem" to "UseSysfsPowerState standby". S3 and S4 are the more
1319     interesting sleep states due to greater energy savings however.
1320 so 1.15 </p>
1321    
1322     </body>
1323     </section>
1324     <section>
1325     <title>Hibernate (S4)</title>
1326     <body>
1327    
1328     <p>
1329     This section introduces hibernation, where a snapshot of the running system is
1330     written to disk before powering off. On resume, the snapshot is loaded and you
1331     can go on working at exactly the point you called hibernate before.
1332 swift 1.1 </p>
1333    
1334     <warn>
1335 so 1.15 Don't exchange non hot-pluggable hardware when suspended. Don't attempt to load
1336     a snapshot with a different kernel image than the one it was created with.
1337     Shutdown any NFS or samba server/client before hibernating.
1338 swift 1.1 </warn>
1339    
1340     <p>
1341 so 1.15 There are two different implementations for S4. The original one is swsusp,
1342 nightmorph 1.39 then there is the newer tuxonice (formerly suspend2) with a nicer interface
1343 swift 1.36 (including fbsplash support). A <uri
1344 nightmorph 1.39 link="http://tuxonice.net/features.html#compare">feature comparison</uri> is
1345     available at the <uri link="http://www.tuxonice.net">tuxonice homepage</uri>.
1346 swift 1.36 There used to be Suspend-to-Disk (pmdisk), a fork of swsusp, but it has been
1347     merged back.
1348 swift 1.1 </p>
1349    
1350     <p>
1351 jkt 1.33 TuxOnIce is not included in the mainline kernel yet, therefore you either have
1352 rane 1.20 to patch your kernel sources with the patches provided by <uri
1353 nightmorph 1.39 link="http://www.tuxonice.net">tuxonice.net</uri> or use
1354 jkt 1.33 <c>sys-kernel/tuxonice-sources</c>.
1355 swift 1.1 </p>
1356    
1357     <p>
1358 jkt 1.33 The kernel part for both swusp and TuxOnIce is as follows:
1359 swift 1.1 </p>
1360    
1361     <pre caption="Kernel configuration for the various suspend types">
1362 nightmorph 1.40 Power Management support ---&gt;
1363 swift 1.1 <comment>(hibernate with swsusp)</comment>
1364 nightmorph 1.39 [*] Hibernation (aka 'suspend to disk')
1365 so 1.15 <comment>(replace /dev/SWAP with your swap partition)</comment>
1366     (/dev/SWAP) Default resume partition
1367 rane 1.20
1368 jkt 1.33 <comment>(hibernate with TuxOnIce)</comment>
1369     Enhanced Hibernation (TuxOnIce)
1370 nightmorph 1.39 --- Image Storage (you need at least one allocator)
1371     [*] File Allocator
1372     [*] Swap Allocator
1373 so 1.15 --- General Options
1374 nightmorph 1.39 [*] Compression support
1375 so 1.15 [ ] Allow Keep Image Mode
1376 nightmorph 1.39 [*] Replace swsusp by default
1377 swift 1.1 </pre>
1378    
1379     <p>
1380 so 1.15 The configuration for swsusp is rather easy. If you didn't store the location
1381     of your swap partition in the kernel config, you can also pass it as a
1382     parameter with the <c>resume=/dev/SWAP</c> directive. If booting is not
1383     possible due to a broken image, use the <c>noresume</c> kernel parameter. The
1384 rane 1.20 <c>hibernate-cleanup</c> init script invalidates swsusp images during the boot
1385     process.
1386 swift 1.1 </p>
1387    
1388 so 1.15 <pre caption="Invalidating swsusp images during the boot process">
1389 rane 1.19 # <i>rc-update add hibernate-cleanup boot</i>
1390 so 1.15 </pre>
1391    
1392 swift 1.1 <p>
1393 so 1.15 To activate hibernate with swsusp, use the hibernate script and set
1394 nightmorph 1.24 <c>UseSysfsPowerState disk</c> in <path>/etc/hibernate/sysfs-disk</path>.
1395 swift 1.1 </p>
1396    
1397     <warn>
1398     Backup your data before doing this. Run <c>sync</c> before executing one of the
1399     commands to have cached data written to disk. First try it outside of X, then
1400     with X running, but not logged in.
1401     </warn>
1402 rane 1.20
1403 swift 1.1 <p>
1404     If you experience kernel panics due to uhci or similar, try to compile USB
1405     support as module and unload the modules before sending your laptop to sleep
1406 nightmorph 1.24 mode. There are configuration options for this in <path>common.conf</path>
1407 swift 1.1 </p>
1408    
1409 so 1.15 <pre caption="Hibernating with swsusp">
1410 nightmorph 1.24 # <i>nano -w /etc/hibernate/common.conf</i>
1411 so 1.15 <comment>(Make sure you have a backup of your data)</comment>
1412 rane 1.19 # <i>hibernate</i>
1413 so 1.15 </pre>
1414    
1415 swift 1.1 <p>
1416 jkt 1.34 The following section discusses the setup of TuxOnIce including fbsplash support
1417     for a nice graphical progress bar during suspend and resume.
1418 so 1.15 </p>
1419    
1420     <p>
1421 rane 1.20 The first part of the configuration is similar to the configuration of swsusp.
1422     In case you didn't store the location of your swap partition in the kernel
1423     config, you have to pass it as a kernel parameter with the
1424 jkt 1.33 <c>resume=swap:/dev/SWAP</c> directive. If booting is not possible due to a
1425     broken image, append the <c>noresume</c> parameter. Additionally, the
1426 jkt 1.34 <c>hibernate-cleanup</c> init script invalidates TuxOnIce images during the boot
1427     process.
1428 so 1.15 </p>
1429    
1430 jkt 1.33 <pre caption="Invalidating TuxOnIce images during the boot process">
1431 rane 1.19 # <i>rc-update add hibernate-cleanup boot</i>
1432 so 1.15 </pre>
1433    
1434 rane 1.20 <p>
1435 nightmorph 1.39 Now edit <path>/etc/hibernate/tuxonice.conf</path>, enable the <c>TuxOnIce</c>
1436 nightmorph 1.24 options you need. Do not enable the <c>fbsplash</c> options in
1437     <c>common.conf</c> just yet.
1438 swift 1.1 </p>
1439    
1440 jkt 1.33 <pre caption="Hibernating with TuxOnIce">
1441 nightmorph 1.39 # <i>nano -w /etc/hibernate/tuxonice.conf</i>
1442 so 1.15 <comment>(Make sure you have a backup of your data)</comment>
1443 rane 1.19 # <i>hibernate</i>
1444 swift 1.8 </pre>
1445    
1446 so 1.15 <p>
1447 rane 1.20 Please configure <c>fbsplash</c> now if you didn't do already. To enable
1448 jkt 1.34 fbsplash support during hibernation, the <c>sys-apps/tuxonice-userui</c> package
1449     is needed. Additionally, you've got to enable the <c>fbsplash</c> USE flag.
1450 so 1.15 </p>
1451    
1452 jkt 1.33 <pre caption="Installing tuxonice-userui">
1453     # <i>echo "sys-apps/tuxonice-userui fbsplash" >> /etc/portage/package.use</i>
1454 nightmorph 1.24 <comment>(It may be marked ~arch, so first it must be keyworded)</comment>
1455 jkt 1.33 # <i>echo "sys-apps/tuxonice-userui" >> /etc/portage/package.keywords</i>
1456     # <i>emerge tuxonice-userui</i>
1457 so 1.15 </pre>
1458    
1459     <p>
1460     The ebuild tells you to make a symlink to the theme you want to use. For
1461     example, to use the <c>livecd-2005.1</c> theme, run the following command:
1462     </p>
1463    
1464     <pre caption="Using the livecd-2005.1 theme during hibernation">
1465 nightmorph 1.39 # <i>ln -sfn /etc/splash/livecd-2005.1 /etc/splash/tuxonice</i>
1466 so 1.15 </pre>
1467    
1468     <p>
1469     If you don't want a black screen in the first part of the resume process, you
1470 jkt 1.33 have to add the <c>tuxoniceui_fbsplash</c> tool to your initrd image. Assuming
1471 so 1.15 you created the initrd image with <c>splash_geninitramfs</c> and saved it as
1472 rane 1.20 <path>/boot/fbsplash-emergence-1024x768</path>, here's how to do that.
1473 so 1.15 </p>
1474    
1475 jkt 1.33 <pre caption="Adding tuxoniceui_fbsplash to an initrd image">
1476 rane 1.19 # <i>mount /boot</i>
1477     # <i>mkdir ~/initrd.d</i>
1478     # <i>cp /boot/fbsplash-emergence-1024x768 ~/initrd.d/</i>
1479     # <i>cd ~/initrd.d</i>
1480     # <i>gunzip -c fbsplash-emergence-1024x768 | cpio -idm --quiet -H newc</i>
1481     # <i>rm fbsplash-emergence-1024x768</i>
1482 jkt 1.33 # <i>cp /usr/sbin/tuxoniceui_fbsplash sbin/</i>
1483     # <i>find . | cpio --quiet --dereference -o -H newc | gzip -9 > /boot/fbsplash-tuxonice-emergence-1024x768</i>
1484 so 1.15 </pre>
1485    
1486     <p>
1487 nightmorph 1.24 Afterwards adjust <path>grub.conf</path> (or <path>lilo.conf</path>) so that
1488 jkt 1.33 your TuxOnIce kernel uses
1489     <path>/boot/fbsplash-tuxonice-emergence-1024x768</path> as initrd image. You can
1490 nightmorph 1.24 now test a dry run to see if everything is setup correctly.
1491 so 1.15 </p>
1492    
1493     <pre caption="Test run for fbsplash hibernation">
1494 jkt 1.33 # <i>tuxoniceui_fbsplash -t</i>
1495 so 1.15 </pre>
1496    
1497     <p>
1498 nightmorph 1.24 Afterwards open <path>/etc/hibernate/common.conf</path> and activate the
1499     fbsplash options. Execute <c>hibernate</c> and enjoy.
1500 so 1.15 </p>
1501    
1502 swift 1.1 </body>
1503     </section>
1504     </chapter>
1505    
1506     <chapter>
1507     <title>Troubleshooting</title>
1508     <section>
1509     <body>
1510    
1511     <p>
1512     <e>Q:</e> I'm trying to change the CPU frequency, but
1513     <path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor</path> does not
1514     exist.
1515     </p>
1516    
1517     <p>
1518     <e>A:</e> Make sure your processor supports CPU frequency scaling and you chose
1519     the right CPUFreq driver for your processor. Here is a list of processors that
1520 jkt 1.34 are supported by cpufreq (kernel 2.6.7): ARM Integrator, ARM-SA1100, ARM-SA1110,
1521     AMD Elan - SC400, SC410, AMD mobile K6-2+, AMD mobile K6-3+, AMD mobile Duron,
1522     AMD mobile Athlon, AMD Opteron, AMD Athlon 64, Cyrix Media GXm, Intel mobile
1523     PIII and Intel mobile PIII-M on certain chipsets, Intel Pentium 4, Intel Xeon,
1524     Intel Pentium M (Centrino), National Semiconductors Geode GX, Transmeta Crusoe,
1525     VIA Cyrix 3 / C3, UltraSPARC-III, SuperH SH-3, SH-4, several "PowerBook" and
1526     "iBook2" and various processors on some ACPI 2.0-compatible systems (only if
1527     "ACPI Processor Performance States" are available to the ACPI/BIOS interface).
1528 swift 1.1 </p>
1529    
1530     <p>
1531     <e>Q:</e> My laptop supports frequency scaling, but
1532     <path>/sys/devices/system/cpu/cpu0/cpufreq/</path> is empty.
1533     </p>
1534    
1535     <p>
1536     <e>A:</e> Look for ACPI related error messages with <c>dmesg | grep ACPI</c>.
1537     Try to update the BIOS, especially if a broken DSDT is reported. You can also
1538     try to fix it yourself (which is beyond the scope of this guide).
1539     </p>
1540    
1541     <p>
1542 rane 1.19 <e>Q:</e> My laptop supports frequency scaling, but according to
1543     <path>/proc/cpuinfo</path> the speed never changes.
1544 swift 1.1 </p>
1545    
1546     <p>
1547 swift 1.8 <e>A:</e> Probably you have activated symmetric multiprocessing support
1548     (CONFIG_SMP) in your kernel. Deactivate it and it should work. Some older
1549 rane 1.20 kernels had a bug causing this. In that case, run <c>emerge x86info</c>, update
1550 jkt 1.34 your kernel as asked and check the current frequency with <c>x86info -mhz</c>.
1551 swift 1.1 </p>
1552    
1553     <p>
1554     <e>Q:</e> I can change the CPU frequency, but the range is not as wide as in
1555     another OS.
1556     </p>
1557    
1558     <p>
1559     <e>A:</e> You can combine frequency scaling with ACPI throttling to get a lower
1560 jkt 1.34 minimum frequency. Notice that throttling doesn't save much energy and is mainly
1561     used for thermal management (keeping your laptop cool and quiet). You can read
1562     the current throttling state with <c>cat /proc/acpi/processor/CPU/throttling</c>
1563     and change it with <c>echo -n "0:x" > /proc/acpi/processor/CPU/limit</c>, where
1564     x is one of the Tx states listed in
1565 swift 1.1 <path>/proc/acpi/processor/CPU/throttling</path>.
1566     </p>
1567    
1568     <p>
1569 swift 1.8 <e>Q:</e> When configuring the kernel, powersave, performance and userspace
1570     governors show up, but that ondemand thing is missing. Where do I get it?
1571     </p>
1572    
1573     <p>
1574     <e>A:</e> The ondemand governor is only included in recent kernel sources. Try
1575     updating them.
1576     </p>
1577    
1578     <p>
1579 swift 1.1 <e>Q:</e> Battery life time seems to be worse than before.
1580     </p>
1581    
1582     <p>
1583     <e>A:</e> Check your BIOS settings. Maybe you forgot to re-enable some of the
1584     settings.
1585     </p>
1586    
1587     <p>
1588     <e>Q:</e> My battery is charged, but KDE reports there would be 0% left and
1589     immediately shuts down.
1590     </p>
1591    
1592     <p>
1593     <e>A:</e> Check that battery support is compiled into your kernel. If you use
1594     it as a module, make sure the module is loaded.
1595     </p>
1596    
1597     <p>
1598 rane 1.20 <e>Q:</e> My system logger reports things like "logger: ACPI group battery /
1599     action battery is not defined".
1600 nightmorph 1.17 </p>
1601    
1602     <p>
1603 rane 1.20 <e>A:</e> This message is generated by the <path>/etc/acpi/default.sh</path>
1604     script that is shipped with acpid. You can safely ignore it. If you like to get
1605     rid of it, you can comment the appropriate line in
1606     <path>/etc/acpi/default.sh</path> as shown below:
1607 nightmorph 1.17 </p>
1608    
1609     <pre caption="Disabling warnings about unknown acpi events">
1610     *) # logger "ACPI action $action is not defined"
1611     </pre>
1612    
1613     <p>
1614 swift 1.1 <e>Q:</e> I have a Dell Inspiron 51XX and I don't get any ACPI events.
1615     </p>
1616    
1617     <p>
1618     <e>A:</e> This seems to be a kernel bug. Read on <uri
1619     link="http://bugme.osdl.org/show_bug.cgi?id=1752">here</uri>.
1620     </p>
1621    
1622     <p>
1623 rane 1.20 <e>Q:</e> I activated the <c>DynamicClocks</c> option in <path>xorg.conf</path>
1624     and now X.org crashes / the screen stays black / my laptop doesn't shutdown
1625 so 1.15 properly.
1626     </p>
1627    
1628     <p>
1629 rane 1.20 <e>A:</e> This happens on some systems. You have to disable
1630     <c>DynamicClocks</c>.
1631 so 1.15 </p>
1632    
1633     <p>
1634 jkt 1.33 <e>Q:</e> I want to use TuxOnIce, but it tells me my swap partition is too
1635 so 1.15 small. Resizing is not an option.
1636     </p>
1637    
1638     <p>
1639 rane 1.20 <e>A:</e> If there is enough free space on your system, you can use the
1640 jkt 1.34 filewriter instead of the swapwriter. The <c>hibernate-script</c> supports it as
1641     well. More information can be found in
1642 jkt 1.33 <path>/usr/src/linux/Documentation/power/tuxonice.txt</path>.
1643 so 1.15 </p>
1644    
1645     <p>
1646 swift 1.1 <e>Q:</e> I just bought a brand new battery, but it only lasts for some
1647     minutes! What am I doing wrong?
1648     </p>
1649    
1650     <p>
1651     <e>A:</e> First follow your manufacturer's advice on how to charge the battery
1652 rane 1.20 correctly.
1653 swift 1.1 </p>
1654    
1655     <p>
1656     <e>Q:</e> The above didn't help. What should I do then?
1657     </p>
1658    
1659     <p>
1660     <e>A:</e> Some batteries sold as "new" are in fact old ones. Try the following:
1661     </p>
1662    
1663     <pre caption="Querying battery state">
1664     $ <i>grep capacity /proc/acpi/battery/BAT0/info</i>
1665     design capacity: 47520 mWh
1666     last full capacity: 41830 mWh
1667     </pre>
1668    
1669     <p>
1670     If the "last full capacity" differs significantly from the design capacity,
1671     your battery is probably broken. Try to claim your warranty.
1672     </p>
1673    
1674 swift 1.8 <p>
1675     <e>Q:</e> My problem is not listed above. Where should I go next?
1676     </p>
1677    
1678     <p>
1679 nightmorph 1.17 <e>A:</e> Don't fear to contact me, <mail link="earthwings@gentoo.org">Dennis
1680 rane 1.20 Nienhüser</mail>, directly. The <uri link="http://forums.gentoo.org">Gentoo
1681     Forums</uri> are a good place to get help as well. If you prefer IRC, try the
1682 nightmorph 1.38 <c>#gentoo-laptop</c> <uri link="irc://irc.gentoo.org">channel</uri>.
1683 swift 1.8 </p>
1684    
1685 swift 1.1 </body>
1686     </section>
1687     </chapter>
1688     </guide>

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