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1<?xml version='1.0' encoding="UTF-8"?> 1<?xml version='1.0' encoding="UTF-8"?>
2<!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> 2<!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/power-management-guide.xml,v 1.15 2005/10/28 14:48:06 so Exp $ --> 3<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/power-management-guide.xml,v 1.40 2009/08/05 14:51:17 nightmorph Exp $ -->
4<guide link="/doc/en/power-management-guide.xml"> 4<guide link="/doc/en/power-management-guide.xml">
5<title>Power Management Guide</title> 5<title>Power Management Guide</title>
6 6
7<author title="Author"> 7<author title="Author">
8 <mail link="fragfred@gmx.de">Dennis Nienhüser</mail> 8 <mail link="earthwings@gentoo.org">Dennis Nienhüser</mail>
9</author>
10<author title="Editor">
11 <mail link="chriswhite@gentoo.org">Chris White</mail>
12</author>
13<author title="Editor">
14 <mail link="nightmorph@gentoo.org">Joshua Saddler</mail>
9</author> 15</author>
10 16
11<abstract> 17<abstract>
12Power Management is the key to extend battery run time on mobile systems like 18Power Management is the key to extend battery run time on mobile systems like
13laptops. This guide assists you setting it up on your laptop. 19laptops. This guide assists you setting it up on your laptop.
15 21
16<!-- The content of this document is licensed under the CC-BY-SA license --> 22<!-- The content of this document is licensed under the CC-BY-SA license -->
17<!-- See http://creativecommons.org/licenses/by-sa/2.5 --> 23<!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
18<license/> 24<license/>
19 25
20<version>1.25</version> 26<version>1.43</version>
21<date>2005-10-02</date> 27<date>2009-08-05</date>
22 28
23<chapter> 29<chapter>
24<title>Introduction</title> 30<title>Introduction</title>
25<section> 31<section>
26<title>Why Power Management?</title>
27<body> 32<body>
28 33
29<p> 34<p>
30Capacity and lifetime of laptop batteries have improved much in the last years. 35Capacity and lifetime of laptop batteries have improved much in the last years.
31Nevertheless modern processors consume much more energy than older ones and 36Nevertheless modern processors consume much more energy than older ones and
35intelligent Power Management policies. 40intelligent Power Management policies.
36</p> 41</p>
37 42
38</body> 43</body>
39</section> 44</section>
40
41<section> 45<section>
42<title>A quick overview</title> 46<title>A Quick Overview</title>
43<body> 47<body>
44 48
45<p> 49<p>
46Please notice that this guide describes Power Management for <e>laptops</e>. 50Please notice that this guide describes Power Management for <e>laptops</e>.
47While some sections might also suite for <e>servers</e>, others do not and may 51While some sections might also suite for <e>servers</e>, others do not and may
53As this guide has become rather long, here's a short overview helping you to 57As this guide has become rather long, here's a short overview helping you to
54find your way through it. 58find your way through it.
55</p> 59</p>
56 60
57<p> 61<p>
58The <e>Prerequisites</e> chapter talks about some requirements that should be 62The <uri link="#doc_chap2">Prerequisites</uri> chapter talks about some
59met before any of the following device individual sections will work. This 63requirements that should be met before any of the following device individual
60includes BIOS settings, kernel configuration and some simplifications in user 64sections will work. This includes BIOS settings, kernel configuration and some
61land. The following three chapters focus on devices that typically consume 65simplifications in user land. The following three chapters focus on devices
62most energy - processor, display and hard drive. Each can be configured 66that typically consume most energy - processor, display and hard drive. Each
63seperately. <e>CPU Power Management</e> shows how to adjust the processor's 67can be configured seperately. <uri link="#doc_chap3">CPU Power Management</uri>
64frequency to save a maximum of energy whithout losing too much performance. A 68shows how to adjust the processor's frequency to save a maximum of energy
65few different tricks prevent your hard drive from working unnecessarily often 69without losing too much performance. A few different tricks prevent your hard
66in <e>Disk Power Management</e> (decreasing noise level as a nice side 70drive from working unnecessarily often in <uri link="#doc_chap5">Disk Power
67effect). Some notes on graphics cards, Wireless LAN and USB finish the device 71Management</uri> (decreasing noise level as a nice side effect). Some notes on
68section in <e>Power Management for other devices</e> while another chapter is 72graphics cards, Wireless LAN and USB finish the device section in <uri
69dedicated to the (rather experimental) <e>sleep states</e>. Last not least 73link="#doc_chap6">Power Management For Other Devices</uri> while another
70<e>Troubleshooting</e> lists common pitfalls. 74chapter is dedicated to the (rather experimental) <uri link="#doc_chap7">sleep
75states</uri>. Last not least <uri link="#doc_chap8">Troubleshooting</uri> lists
76common pitfalls.
71</p> 77</p>
72 78
73</body> 79</body>
74</section>
75
76<section> 80</section>
81<section>
77<title>Power Budget for each component</title> 82<title>Power Budget For Each Component</title>
78<body> 83<body>
79 84
80<figure link="/images/energy-budget.png" short="Which component consumes how 85<figure link="/images/energy-budget.png" short="Which component consumes how
81much energy?" caption="Power budget for each component"/> 86much energy?" caption="Power budget for each component"/>
82 87
93</chapter> 98</chapter>
94 99
95<chapter> 100<chapter>
96<title>Prerequisites</title> 101<title>Prerequisites</title>
97<section> 102<section>
98<title>What has to be done first</title>
99<body>
100
101<p>
102Before going into the details on making individual devices Power Management
103aware, make sure certain requirements are met. After controlling the BIOS
104settings, some kernel options want to be enabled - these are in short ACPI,
105sleep states and CPU frequency scaling. As power saving most of the time comes
106along with performance loss or increased latency, it should only be enabled
107when running on batteries. That's where a new runlevel <e>battery</e> comes in
108handy.
109</p>
110
111</body> 103<body>
112</section> 104
105<p>
106Before discussing the details of making individual devices Power Management
107aware, make sure certain requirements are met. After controlling BIOS settings,
108some kernel options want to be enabled - these are in short ACPI, sleep states
109and CPU frequency scaling. As power saving most of the time comes along with
110performance loss or increased latency, it should only be enabled when running
111on batteries. That's where a new runlevel <e>battery</e> comes in handy.
112</p>
113
114</body>
113<section> 115</section>
116<section>
114<title>The BIOS part</title> 117<title>The BIOS Part</title>
115<body> 118<body>
116 119
117<p> 120<p>
118First have a look into your BIOS Power Management settings. The best way is to 121First have a look into your BIOS Power Management settings. The best way is to
119combine BIOS and operating system policies, but for the moment it's better to 122combine BIOS and operating system policies, but for the moment it's better to
123</p> 126</p>
124 127
125</body> 128</body>
126</section> 129</section>
127<section> 130<section>
131<title>Setting USE Flags</title>
132<body>
133
134<p>
135Please 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
137system 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
139you forgot to set one of these flags, you can recompile affected packages using
140the <c>--newuse</c> flag in <c>emerge</c>, see <c>man emerge</c>.
141</p>
142
143</body>
144</section>
145<section>
128<title>Configuring the kernel</title> 146<title>Configuring The Kernel</title>
129<body> 147<body>
130 148
131<p> 149<p>
132ACPI (Advanced Configuration and Power Interface) support in the kernel is 150ACPI (Advanced Configuration and Power Interface) support in the kernel is
133still work in progress. Using a recent kernel will make sure you'll get the 151still work in progress. Using a recent kernel will make sure you'll get the
134most out of it. 152most out of it.
135</p> 153</p>
136 154
137<p> 155<p>
138There are different kernel sources in Portage. I'd recommend using 156There are different kernel sources in Portage. I'd recommend using
139<c>gentoo-sources</c> or <c>suspend2-sources</c>. The latter contains patches 157<c>gentoo-sources</c> or <c>tuxonice-sources</c>. The latter contains patches
140for Software Suspend 2, see the chapter about sleep states for details. When 158for TuxOnIce, see the chapter about <uri link="#doc_chap7">sleep states</uri>
141configuring the kernel, activate at least these options: 159for more details. When configuring the kernel, activate at least these options:
142</p> 160</p>
143 161
144<pre caption="Minimum kernel setup for Power Management (Kernel 2.6)"> 162<pre caption="Minimum kernel setup for Power Management (Kernel 2.6)">
145Power Management Options ---&gt; 163Power management and ACPI options ---&gt;
146 [*] Power Management Support 164[*] Power Management support
147 [ ] Software Suspend 165 [ ] Software Suspend
148 166
149 ACPI( Advanced Configuration and Power Interface ) Support ---&gt; 167 ACPI( Advanced Configuration and Power Interface ) Support ---&gt;
150 [*] ACPI Support 168 [ ] Deprecated /proc/acpi/ files
151 [ ] Sleep States
152 [ ] /proc/acpi/sleep (deprecated)
153 [*] AC Adapter 169 [*] AC Adapter
154 [*] Battery 170 [*] Battery
155 &lt;M&gt; Button 171 &lt;M&gt; Button
156 &lt;M&gt; Video 172 &lt;M&gt; Video
157 [ ] Generic Hotkey 173 [ ] Generic Hotkey
163 &lt; &gt; Toshiba Laptop Extras 179 &lt; &gt; Toshiba Laptop Extras
164 (0) Disable ACPI for systems before Jan 1st this year 180 (0) Disable ACPI for systems before Jan 1st this year
165 [ ] Debug Statements 181 [ ] Debug Statements
166 [*] Power Management Timer Support 182 [*] Power Management Timer Support
167 &lt; &gt; ACPI0004,PNP0A05 and PNP0A06 Container Driver (EXPERIMENTAL) 183 &lt; &gt; ACPI0004,PNP0A05 and PNP0A06 Container Driver (EXPERIMENTAL)
168 184
169 CPU Frequency Scaling ---&gt; 185 CPU Frequency Scaling ---&gt;
170 [*] CPU Frequency scaling 186 [*] CPU Frequency scaling
171 [ ] Enable CPUfreq debugging 187 [ ] Enable CPUfreq debugging
172 &lt; &gt; CPU frequency translation statistics 188 &lt; &gt; CPU frequency translation statistics
173 [ ] CPU frequency translation statistics details 189 [ ] CPU frequency translation statistics details
186(see below). If you own an ASUS, Medion, IBM Thinkpad or Toshiba laptop, enable 202(see below). If you own an ASUS, Medion, IBM Thinkpad or Toshiba laptop, enable
187the appropriate section. 203the appropriate section.
188</p> 204</p>
189 205
190<p> 206<p>
191The kernel has to know how to enable CPU frequency scaling on your processor. As 207The kernel has to know how to enable CPU frequency scaling on your processor.
192each type of CPU has a different interface, you've got to choose the right 208As each type of CPU has a different interface, you've got to choose the right
193driver for your processor. Be careful here - enabling <e>Intel Pentium 4 clock 209driver for your processor. Be careful here - enabling <c>Intel Pentium 4 clock
194modulation</e> on a Pentium M system will lead to strange results for example. 210modulation</c> on a Pentium M system will lead to strange results for example.
195Consult the kernel documentation if you're unsure which one to take. 211Consult the kernel documentation if you're unsure which one to take.
196</p> 212</p>
197 213
198<p> 214<p>
199Compile your kernel, make sure the right modules get loaded at startup and boot 215Compile your kernel, make sure the right modules get loaded at startup and boot
200into your new ACPI-enabled kernel. Next run <c>emerge sys-power/acpid</c> to get 216into your new ACPI-enabled kernel. Next run <c>emerge sys-power/acpid</c> to
201the acpi daemon. This one informs you about events like switching from AC to 217get the acpi daemon. This one informs you about events like switching from AC
202battery or closing the lid. Make sure the modules are loaded if you didn't 218to battery or closing the lid. Make sure the modules are loaded if you didn't
203compile them into the kernel and start acpid by executing 219compile them into the kernel and start acpid by executing <c>/etc/init.d/acpid
204<c>/etc/init.d/acpid start</c>. Run <c>rc-update add acpid default</c> to load 220start</c>. Run <c>rc-update add acpid default</c> to load it on startup. You'll
205it on startup. You'll soon see how to use it. 221soon see how to use it.
206</p> 222</p>
207 223
208<pre caption="Installing acpid"> 224<pre caption="Installing acpid">
209# <i>emerge sys-power/acpid</i> 225# <i>emerge sys-power/acpid</i>
210# <i>/etc/init.d/acpid start</i> 226# <i>/etc/init.d/acpid start</i>
212</pre> 228</pre>
213 229
214</body> 230</body>
215</section> 231</section>
216<section> 232<section>
217<title>Creating a "battery" runlevel</title> 233<title>Creating A "battery" Runlevel</title>
218<body> 234<body>
219 235
220<p> 236<p>
221The default policy will be to enable Power Management only when needed - 237The default policy will be to enable Power Management only when needed -
222running on batteries. To make the switch between AC and battery convenient, 238running on batteries. To make the switch between AC and battery convenient,
223create a runlevel <e>battery</e> that holds all the scripts starting and 239create a runlevel <c>battery</c> that holds all the scripts starting and
224stopping Power Management. 240stopping Power Management.
225</p> 241</p>
226 242
227<note> 243<note>
228You can safely skip this section if you don't like the idea of having another 244You can safely skip this section if you don't like the idea of having another
229runlevel. However, skipping this step will make the rest a bit trickier to set 245runlevel. However, skipping this step will make the rest a bit trickier to set
230up. The next sections assume a runlevel <e>battery</e> exists. 246up. The next sections assume a runlevel <c>battery</c> exists.
231</note> 247</note>
232 248
233<pre caption="Creating a battery runlevel"> 249<pre caption="Creating a battery runlevel">
234# <i>cd /etc/runlevels</i> 250# <i>cd /etc/runlevels</i>
235# <i>cp -a default battery</i> 251# <i>cp -a default battery</i>
236</pre> 252</pre>
237 253
238<p> 254<p>
239Finished. Your new runlevel <e>battery</e> contains everything like 255Finished. Your new runlevel <c>battery</c> contains everything like
240<e>default</e>, but there is no automatic switch between both yet. Time to 256<c>default</c>, but there is no automatic switch between both yet. Time to
241change it. 257change it.
242</p> 258</p>
243 259
244</body> 260</body>
245</section> 261</section>
246<section> 262<section>
247<title>Reacting on ACPI events</title> 263<title>Reacting On ACPI Events</title>
248<body> 264<body>
249 265
250<p> 266<p>
251Typical ACPI events are closing the lid, changing the power source or pressing 267Typical ACPI events are closing the lid, changing the power source or pressing
252the sleep button. An important event is changing the power source, which should 268the sleep button. An important event is changing the power source, which should
259<c>on_ac_power</c> command from <c>sys-power/powermgmt-base</c> - make sure the 275<c>on_ac_power</c> command from <c>sys-power/powermgmt-base</c> - make sure the
260package is installed on your system. 276package is installed on your system.
261</p> 277</p>
262 278
263<pre caption="Installing powermgt-base"> 279<pre caption="Installing powermgt-base">
264<i># emerge powermgmt-base</i> 280# <i>emerge powermgmt-base</i>
265</pre> 281</pre>
266 282
267<p> 283<p>
268You are now able to determine the power source by executing 284You are now able to determine the power source by executing <c>on_ac_power
269<c>on_ac_power &amp;&amp; echo AC available || echo Running on batteries</c> in 285&amp;&amp; echo AC available || echo Running on batteries</c> in a shell. The
270a shell. The script below is responsible for changing runlevels. Save it as 286script below is responsible for changing runlevels. Save it as
271<path>/etc/acpi/actions/pmg_switch_runlevel.sh</path>. 287<path>/etc/acpi/actions/pmg_switch_runlevel.sh</path>.
272</p> 288</p>
273 289
274<pre caption="/etc/acpi/actions/pmg_switch_runlevel.sh"> 290<pre caption="/etc/acpi/actions/pmg_switch_runlevel.sh">
275#!/bin/bash 291#!/bin/bash
280<comment># END configuration</comment> 296<comment># END configuration</comment>
281 297
282 298
283if [ ! -d "/etc/runlevels/${RUNLEVEL_AC}" ] 299if [ ! -d "/etc/runlevels/${RUNLEVEL_AC}" ]
284then 300then
285 logger "${0}: Runlevel ${RUNLEVEL_AC} does not exist. Aborting." 301 logger "${0}: Runlevel ${RUNLEVEL_AC} does not exist. Aborting."
286 exit 1 302 exit 1
287fi 303fi
288 304
289if [ ! -d "/etc/runlevels/${RUNLEVEL_BATTERY}" ] 305if [ ! -d "/etc/runlevels/${RUNLEVEL_BATTERY}" ]
290then 306then
291 logger "${0}: Runlevel ${RUNLEVEL_BATTERY} does not exist. Aborting." 307 logger "${0}: Runlevel ${RUNLEVEL_BATTERY} does not exist. Aborting."
292 exit 1 308 exit 1
293fi 309fi
294 310
295if on_ac_power 311if on_ac_power
296then 312then
297 if [[ "$(cat /var/lib/init.d/softlevel)" != "${RUNLEVEL_AC}" ]] 313 if [[ "$(&lt;/var/lib/init.d/softlevel)" != "${RUNLEVEL_AC}" ]]
298 then 314 then
299 logger "Switching to ${RUNLEVEL_AC} runlevel" 315 logger "Switching to ${RUNLEVEL_AC} runlevel"
300 /sbin/rc ${RUNLEVEL_AC} 316 /sbin/rc ${RUNLEVEL_AC}
301 fi 317 fi
302elif [[ "$(cat /var/lib/init.d/softlevel)" != "${RUNLEVEL_BATTERY}" ]] 318elif [[ "$(&lt;/var/lib/init.d/softlevel)" != "${RUNLEVEL_BATTERY}" ]]
303then 319then
304 logger "Switching to ${RUNLEVEL_BATTERY} runlevel" 320 logger "Switching to ${RUNLEVEL_BATTERY} runlevel"
305 /sbin/rc ${RUNLEVEL_BATTERY} 321 /sbin/rc ${RUNLEVEL_BATTERY}
306fi 322fi
307</pre> 323</pre>
308 324
309<p> 325<p>
310Dont forget to run <c>chmod +x /etc/acpi/actions/pmg_switch_runlevel.sh</c> to 326Dont forget to run <c>chmod +x /etc/acpi/actions/pmg_switch_runlevel.sh</c> to
311make the script executable. The last thing that needs to be done is calling the 327make the script executable. The last thing that needs to be done is calling the
312script whenever the power source changes. That's done by catching ACPI events 328script whenever the power source changes. That's done by catching ACPI events
313with the help of <c>acpid</c>. First you need to know which events are 329with the help of <c>acpid</c>. First you need to know which events are
314generated when the power source changes. The events are called 330generated when the power source changes. The events are called
315<e>ac_adapter</e> and <e>battery</e> on most laptops, but it might be different 331<c>ac_adapter</c> and <c>battery</c> on most laptops, but it might be different
316on yours. 332on yours.
317</p> 333</p>
318 334
319<pre caption="Determining ACPI events for changing the power source"> 335<pre caption="Determining ACPI events for changing the power source">
320<i># tail -f /var/log/acpid | grep "received event"</i> 336# <i>tail -f /var/log/messages | grep "received event"</i>
321</pre> 337</pre>
322 338
323<p> 339<p>
324Run the command above and pull the power cable. You should see something 340Run the command above and pull the power cable. You should see something like
325like this: 341this:
326</p> 342</p>
327 343
328<pre caption="Sample output for power source changes"> 344<pre caption="Sample output for power source changes">
329[Tue Sep 20 17:39:06 2005] received event "ac_adapter AC 00000080 00000000" 345[Tue Sep 20 17:39:06 2005] received event "ac_adapter AC 00000080 00000000"
330[Tue Sep 20 17:39:06 2005] received event "battery BAT0 00000080 00000001" 346[Tue Sep 20 17:39:06 2005] received event "battery BAT0 00000080 00000001"
331</pre> 347</pre>
332 348
333<p> 349<p>
334The interesting part is the quoted string after <e>received event</e>. It will 350The interesting part is the quoted string after <c>received event</c>. It will
335be matched by the event line in the files you are going to create below. Don't 351be matched by the event line in the files you are going to create below. Don't
336worry if your system generates multiple events or always the same. As long as 352worry if your system generates multiple events or always the same. As long as
337any event is generated, runlevel changing will work. 353any event is generated, runlevel changing will work.
338</p> 354</p>
339 355
354<p> 370<p>
355Finally acpid has to be restarted to recognize the changes. 371Finally acpid has to be restarted to recognize the changes.
356</p> 372</p>
357 373
358<pre caption="Finishing runlevel switching with acpid"> 374<pre caption="Finishing runlevel switching with acpid">
359<i># /etc/init.d/acpid restart</i> 375# <i>/etc/init.d/acpid restart</i>
360</pre> 376</pre>
361 377
362<p> 378<p>
363Give it a try: Plug AC in and out and watch syslog for the "Switching to AC 379Give it a try: Plug AC in and out and watch syslog for the "Switching to AC
364mode" or "Switching to battery mode" messages. See the Troubleshooting 380mode" or "Switching to battery mode" messages. See the <uri
365section if the script is not able to detect the power source correctly. 381link="#doc_chap8">Troubleshooting section</uri> if the script is not able to
382detect the power source correctly.
366</p> 383</p>
367 384
368<p> 385<p>
369Due to the nature of the event mechanism, your laptop will boot into runlevel 386Due to the nature of the event mechanism, your laptop will boot into runlevel
370<e>default</e> regardless of the AC/battery state. This is fine when running 387<c>default</c> regardless of the AC/battery state. This is fine when running
371from AC, but we'd like to boot into the battery runlevel otherwise. One 388from AC, but we'd like to boot into the battery runlevel otherwise. One
372solution would be to add another entry to the boot loader with the parameter 389solution would be to add another entry to the boot loader with the parameter
373<c>softlevel=battery</c>, but it's likely to forget choosing it. A better way 390<c>softlevel=battery</c>, but it's likely to forget choosing it. A better way
374is faking an ACPI event in the end of the boot process and letting 391is faking an ACPI event in the end of the boot process and letting
375<path>pmg_switch_runlevel.sh</path> script decide whether a 392<path>pmg_switch_runlevel.sh</path> script decide whether a runlevel change is
376runlevel change is necessary. Open <path>/etc/conf.d/local.start</path> in your 393necessary. Open <path>/etc/conf.d/local.start</path> in your favourite editor
377favourite editor and add these lines: 394and add these lines:
378</p> 395</p>
379 396
380<pre caption="Runlevel adjustment at boot time by editing local.start"> 397<pre caption="Runlevel adjustment at boot time by editing local.start">
381<comment># Fake acpi event to switch runlevel if running on batteries</comment> 398<comment># Fake acpi event to switch runlevel if running on batteries</comment>
382/etc/acpi/actions/pmg_switch_runlevel.sh "battery/battery" 399/etc/acpi/actions/pmg_switch_runlevel.sh "battery/battery"
383</pre> 400</pre>
384 401
385<p> 402<p>
386Prepared like this you can activate Power Management policies for individual 403Prepared like this you can activate Power Management policies for individual
387devices. 404devices.
388</p> 405</p>
389 406
390</body> 407</body>
391</section> 408</section>
392</chapter> 409</chapter>
393 410
394<chapter> 411<chapter>
395<title>CPU Power Management</title> 412<title>CPU Power Management</title>
396<section> 413<section>
414<body>
415
416<p>
417Mobile processors can operate at different frequencies. Some allow changing
418voltage as well. Most of the time your CPU doesn't need to run at full speed
419and scaling it down will save much energy - often without any performance
420decrease.
421</p>
422
423</body>
424</section>
425<section>
397<title>Some technical terms</title> 426<title>Some Technical Terms</title>
398<body> 427<body>
399 428
400<p> 429<p>
401CPU frequency scaling brings up some technical terms that might be unknown to 430CPU frequency scaling brings up some technical terms that might be unknown to
402you. Here's a quick introduction. 431you. Here's a quick introduction.
403</p> 432</p>
404 433
405<p> 434<p>
406First of all, the kernel has to be able to change the processor's frequency. 435First of all, the kernel has to be able to change the processor's frequency.
407The <e>CPUfreq processor driver</e> knows the commands to do it on your CPU. 436The <b>CPUfreq processor driver</b> knows the commands to do it on your CPU.
408Thus it's important to choose the right one in your kernel. You should 437Thus it's important to choose the right one in your kernel. You should already
409already have done it above. Once the kernel knows how to change frequencies, 438have done it above. Once the kernel knows how to change frequencies, it has to
410it has to know which frequency it should set. This is done according to the 439know which frequency it should set. This is done according to the <b>policy</b>
411<e>policy</e> which consists of a <e>CPUfreq policy</e> and a 440which consists of a <b>CPUfreq policy</b> and a <b>governor</b>. A CPUfreq
412<e>governor</e>. A CPUfreq policy are just two numbers which define a range 441policy are just two numbers which define a range the frequency has to stay
413the frequency has to stay between - minimal and maximal frequency. The 442between - minimal and maximal frequency. The governor now decides which of the
414governor now decides which of the available frequencies in between minimal 443available frequencies in between minimal and maximal frequency to choose. For
415and maximal frequency to choose. For example, the <e>powersave governor</e> 444example, the <b>powersave governor</b> always chooses the lowest frequency
416always chooses the lowest frequency available, the <e>performance 445available, the <b>performance governor</b> the highest one. The <b>userspace
417governor</e> the highest one. The <e>userspace governor</e> makes no decision 446governor</b> makes no decision but chooses whatever the user (or a program in
418but chooses whatever the user (or a program in userspace) wants - which means 447userspace) wants - which means it reads the frequency from
419it reads the frequency from
420<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed</path>. 448<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed</path>.
421</p> 449</p>
422 450
423<p> 451<p>
424This doesn't sound like dynamic frequency changes yet and in fact it isn't. 452This doesn't sound like dynamic frequency changes yet and in fact it isn't.
425Dynamics however can be accomplished with various approaches. For example, 453Dynamics however can be accomplished with various approaches. For example, the
426the <e>ondemand governor</e> makes its decisions depending on the current CPU 454<b>ondemand governor</b> makes its decisions depending on the current CPU load.
427load. The same is done by various userland tools like <c>cpudyn</c>, 455The same is done by various userland tools like <c>cpudyn</c>, <c>cpufreqd</c>,
428<c>cpufreqd</c>, <c>powernowd</c> and many more. ACPI events can be used to 456<c>powernowd</c> and many more. ACPI events can be used to enable or disable
429enable or disable dynamic frequency changes depending on power source. 457dynamic frequency changes depending on power source.
430</p> 458</p>
431 459
432</body> 460</body>
433</section>
434<section> 461</section>
462<section>
435<title>Setting the frequency manually</title> 463<title>Setting The Frequency Manually</title>
436<body> 464<body>
437 465
438<p> 466<p>
439Decreasing CPU speed and voltage has two advantages: On the one hand less 467Decreasing CPU speed and voltage has two advantages: On the one hand less
440energy is consumed, on the other hand there is thermal improvement as your 468energy is consumed, on the other hand there is thermal improvement as your
443between performance loss and energy saving. 471between performance loss and energy saving.
444</p> 472</p>
445 473
446<note> 474<note>
447Not every laptop supports frequency scaling. If unsure, have a look at the list 475Not every laptop supports frequency scaling. If unsure, have a look at the list
448of supported processors in the <e>Troubleshooting</e> section to verify your's 476of supported processors in the <uri link="#doc_chap8">Troubleshooting</uri>
449is supported. 477section to verify yours is supported.
450</note> 478</note>
451 479
452<p> 480<p>
453It's time to test whether CPU frequency changing works. Let's install another 481It's time to test whether CPU frequency changing works. Let's install another
454tool which is very handy for debugging purposes: <c>sys-power/cpufrequtils</c> 482tool which is very handy for debugging purposes: <c>sys-power/cpufrequtils</c>
480 508
481<p> 509<p>
482Now play around with <c>cpufreq-set</c> to make sure frequency switching works. 510Now play around with <c>cpufreq-set</c> to make sure frequency switching works.
483Run <c>cpufreq-set -g ondemand</c> for example to activate the ondemand 511Run <c>cpufreq-set -g ondemand</c> for example to activate the ondemand
484governor and verify the change with <c>cpufreq-info</c>. If it doesn't work as 512governor and verify the change with <c>cpufreq-info</c>. If it doesn't work as
485expected, you might find help in the Troubleshooting section in the end of this 513expected, you might find help in the <uri link="#doc_chap8">Troubleshooting
486guide. 514section</uri> in the end of this guide.
487</p> 515</p>
488 516
489</body> 517</body>
490</section> 518</section>
491<section> 519<section>
494 522
495<p> 523<p>
496The above is quite nice, but not doable in daily life. Better let your system 524The above is quite nice, but not doable in daily life. Better let your system
497set the appropriate frequency automatically. There are many different 525set the appropriate frequency automatically. There are many different
498approaches to do this. The following table gives a quick overview to help you 526approaches to do this. The following table gives a quick overview to help you
499decide on one of them. It's roughly seperated in three categories 527decide on one of them. It's roughly separated in three categories <b>kernel</b>
500<e>kernel</e> for approaches that only need kernel support, <e>daemon</e> for 528for approaches that only need kernel support, <b>daemon</b> for programs that
501programs that run in the background and <e>graphical</e> for programs that 529run in the background and <b>graphical</b> for programs that provide a GUI for
502provide a GUI for easy configuration and changes. 530easy configuration and changes.
503</p> 531</p>
504 532
505<table> 533<table>
506<tr> 534<tr>
507 <th>Name</th> 535 <th>Name</th>
530 <ti>Kernel</ti> 558 <ti>Kernel</ti>
531 <ti>CPU load</ti> 559 <ti>CPU load</ti>
532 <ti>N.A.</ti> 560 <ti>N.A.</ti>
533 <ti>N.A.</ti> 561 <ti>N.A.</ti>
534 <ti> 562 <ti>
535 Unlike the ondemand governor, conversative doesn't jump to maximum 563 Unlike the ondemand governor, conversative doesn't jump to maximum
536 frequency when CPU load is high, but increases the frequency step by 564 frequency when CPU load is high, but increases the frequency step by step.
537 step. Further tuning through files in 565 Further tuning through files in
538 <path>/sys/devices/system/cpu/cpu0/cpufreq/ondemand/</path>. Still 566 <path>/sys/devices/system/cpu/cpu0/cpufreq/ondemand/</path>. Still requires
539 requires userland tools (programs, scripts) if governor switching or 567 userland tools (programs, scripts) if governor switching or similar is
540 similar is desired. 568 desired.
541 </ti> 569 </ti>
542</tr> 570</tr>
543<tr> 571<tr>
544 <ti><uri link="http://mnm.uib.es/~gallir/cpudyn/">cpudyn</uri></ti> 572 <ti><uri link="http://mnm.uib.es/~gallir/cpudyn/">cpudyn</uri></ti>
545 <ti>Daemon</ti> 573 <ti>Daemon</ti>
552 </ti> 580 </ti>
553</tr> 581</tr>
554<tr> 582<tr>
555 <ti><uri link="http://sourceforge.net/projects/cpufreqd/">cpufreqd</uri></ti> 583 <ti><uri link="http://sourceforge.net/projects/cpufreqd/">cpufreqd</uri></ti>
556 <ti>Daemon</ti> 584 <ti>Daemon</ti>
557 <ti>Battery state, CPU load, temperature, running programs</ti> 585 <ti>Battery state, CPU load, temperature, running programs and more</ti>
558 <ti>All available</ti> 586 <ti>All available</ti>
559 <ti>None</ti> 587 <ti>None</ti>
560 <ti> 588 <ti>
561 Sophisticated (but also complicated) setup. 589 Sophisticated (but somewhat complicated) setup. Extendible through plugins
590 like sensor monitoring (lm_sensors) or coordinating some NVidia based
591 graphics card memory and core. Cpufreqd is SMP aware and can optionally be
592 controlled manually at runtime.
562 </ti> 593 </ti>
563</tr> 594</tr>
564<tr> 595<tr>
565 <ti> 596 <ti>
566 <uri link="http://www.deater.net/john/powernowd.html">powernowd</uri> 597 <uri link="http://www.deater.net/john/powernowd.html">powernowd</uri>
573 Supports SMP. 604 Supports SMP.
574 </ti> 605 </ti>
575</tr> 606</tr>
576<tr> 607<tr>
577 <ti> 608 <ti>
578 <uri link="http://fatcat.ftj.agh.edu.pl/~nelchael/index.php?cat=projs&amp;subcat=ncpufreqd&amp;language=en">ncpufreqd</uri> 609 <uri
610 link="http://projects.simpledesigns.com.pl/project/ncpufreqd/">ncpufreqd</uri>
579 </ti> 611 </ti>
580 <ti>Daemon</ti> 612 <ti>Daemon</ti>
581 <ti>Temperature</ti> 613 <ti>Temperature</ti>
582 <ti>None</ti> 614 <ti>None</ti>
583 <ti>Powersave, performance</ti> 615 <ti>Powersave, performance</ti>
623 655
624<p> 656<p>
625While adjusting the frequency to the current load looks simple at a first 657While adjusting the frequency to the current load looks simple at a first
626glance, it's not such a trivial task. A bad algorithm can cause switching 658glance, it's not such a trivial task. A bad algorithm can cause switching
627between two frequencies all the time or wasting energy when setting frequency 659between two frequencies all the time or wasting energy when setting frequency
628to an unnecessary high level. 660to an unnecessary high level.
629</p> 661</p>
630 662
631<p> 663<p>
632Which one to choose? If you have no idea about it, try <c>cpufreqd</c>: 664Which one to choose? If you have no idea about it, try <c>cpufreqd</c>:
633</p> 665</p>
637</pre> 669</pre>
638 670
639<p> 671<p>
640<c>cpufreqd</c> can be configured by editing <path>/etc/cpufreqd.conf</path>. 672<c>cpufreqd</c> can be configured by editing <path>/etc/cpufreqd.conf</path>.
641The default one that ships with cpufreqd may look a bit confusing. I recommend 673The default one that ships with cpufreqd may look a bit confusing. I recommend
642replacing it with the one from Gentoo developer Henrik Brix Andersen (see 674replacing it with the one from former Gentoo developer Henrik Brix Andersen
643below). 675(see below). Please notice that you need cpufreqd-2.0.0 or later. Earlier
676versions have a different syntax for the config file.
644</p> 677</p>
645 678
646<pre caption="/etc/cpufreqd.conf"> 679<pre caption="/etc/cpufreqd.conf (cpufreqd-2.0.0 and later)">
647[General] 680[General]
648pidfile=/var/run/cpufreqd.pid 681pidfile=/var/run/cpufreqd.pid
649poll_interval=2 682poll_interval=3
650pm_type=acpi 683enable_plugins=acpi_ac, acpi_battery
684enable_remote=1
685remote_group=wheel
651verbosity=5 686verbosity=5
687[/General]
652 688
653[Profile] 689[Profile]
654name=ondemand 690name=ondemand
655minfreq=0% 691minfreq=0%
656maxfreq=100% 692maxfreq=100%
657policy=ondemand 693policy=ondemand
694[/Profile]
658 695
659[Profile] 696[Profile]
660name=conservative 697name=conservative
661minfreq=0% 698minfreq=0%
662maxfreq=100% 699maxfreq=100%
663policy=conservative 700policy=conservative
701[/Profile]
664 702
665[Profile] 703[Profile]
666name=powersave 704name=powersave
667minfreq=0% 705minfreq=0%
668maxfreq=100% 706maxfreq=100%
669policy=powersave 707policy=powersave
708[/Profile]
670 709
671[Profile] 710[Profile]
672name=performance 711name=performance
673minfreq=0% 712minfreq=0%
674maxfreq=100% 713maxfreq=100%
675policy=performance 714policy=performance
715[/Profile]
676 716
677[Rule] 717[Rule]
678name=battery 718name=battery
679ac=off 719ac=off
680profile=conservative 720profile=conservative
721[/Rule]
681 722
682[Rule] 723[Rule]
683name=battery_low 724name=battery_low
684ac=off 725ac=off
685battery_interval=0-10 726battery_interval=0-10
686profile=powersave 727profile=powersave
728[/Rule]
687 729
688[Rule] 730[Rule]
689name=ac 731name=ac
690ac=on 732ac=on
691profile=ondemand 733profile=ondemand
734[/Rule]
692</pre> 735</pre>
693 736
694<p> 737<p>
695Now you can start the cpufreqd daemon. Add it to the <e>default</e> and 738Now you can start the cpufreqd daemon. Add it to the <c>default</c> and
696<e>battery</e> runlevel as well. 739<c>battery</c> runlevel as well.
697</p> 740</p>
698 741
699<pre caption="Starting cpufreqd"> 742<pre caption="Starting cpufreqd">
700# <i>rc-update add cpufreqd default battery</i> 743# <i>rc-update add cpufreqd default battery</i>
701# <i>rc</i> 744# <i>rc</i>
702</pre> 745</pre>
746
747<p>
748Sometimes it can be desirable to select another policy than the daemon chooses,
749for example when battery power is low, but you know that AC will be available
750soon. In that case you can turn on cpufreqd's manual mode with <c>cpufreqd-set
751manual</c> and select one of your configured policies (as listed by
752<c>cpufreqd-get</c>). You can leave manual mode by executing <c>cpufreqd-set
753dynamic</c>.
754</p>
703 755
704<warn> 756<warn>
705Do not run more than one of the above programs at the same time. It may cause 757Do not run more than one of the above programs at the same time. It may cause
706confusion like switching between two frequencies all the time. 758confusion like switching between two frequencies all the time.
707</warn> 759</warn>
708 760
709</body> 761</body>
710</section> 762</section>
711
712<section> 763<section>
713<title>Verifying the result</title> 764<title>Verifying the result</title>
714
715<body> 765<body>
716 766
717<p> 767<p>
718The last thing to check is that your new policies do a good job. An easy way to 768The last thing to check is that your new policies do a good job. An easy way to
719do so is monitoring CPU speed while working with your laptop: 769do so is monitoring CPU speed while working with your laptop:
722<pre caption="Monitoring CPU speed"> 772<pre caption="Monitoring CPU speed">
723# <i>watch grep \"cpu MHz\" /proc/cpuinfo</i> 773# <i>watch grep \"cpu MHz\" /proc/cpuinfo</i>
724</pre> 774</pre>
725 775
726<p> 776<p>
727If <path>/proc/cpuinfo</path> doesn't get updated (see Troubleshooting), 777If <path>/proc/cpuinfo</path> doesn't get updated (see <uri
728monitor the CPU frequency with: 778link="#doc_chap8">Troubleshooting</uri>), monitor the CPU frequency with
779<c>sys-apps/x86info</c>:
729</p> 780</p>
730 781
731<pre caption="Alternative CPU speed monitoring"> 782<pre caption="Alternative CPU speed monitoring">
732# <i>watch x86info -mhz</i> 783# <i>watch x86info -mhz</i>
733</pre> 784</pre>
734 785
735<p> 786<p>
736Depending on your setup, CPU speed should increase on heavy load, decrease on 787Depending on your setup, CPU speed should increase on heavy load, decrease on
737no activity or just stay at the same level. When using cpufreqd and verbosity 788no activity or just stay at the same level. When using <c>cpufreqd</c> and
738set to 5 or higher in <path>cpufreqd.conf</path> you'll get additional 789verbosity set to 5 or higher in <path>cpufreqd.conf</path> you'll get
739information about what's happening reported to syslog. 790additional information about what's happening reported to <c>syslog</c>.
740</p> 791</p>
741 792
742</body> 793</body>
743</section> 794</section>
744</chapter> 795</chapter>
745 796
746<chapter> 797<chapter>
747<title>LCD Power Management</title> 798<title>LCD Power Management</title>
748<section> 799<section>
749<title>Energy consumer no. 1</title>
750<body> 800<body>
751 801
752<p> 802<p>
753As you can see in <uri link="#doc_chap1_fig1">figure 1.1</uri>, the LCD display 803As you can see in <uri link="#doc_chap1_fig1">figure 1.1</uri>, the LCD
754consumes the biggest part of energy (might not be the case for non-mobile 804display consumes the biggest part of energy (might not be the case for
755CPU's). Thus it's quite important not only to shut the display off when not 805non-mobile CPU's). Thus it's quite important not only to shut the display off
756needed, but also to reduce it's backlight if possible. Most laptops offer the 806when not needed, but also to reduce it's backlight if possible. Most laptops
757possibility to control the backlight dimming. 807offer the possibility to control the backlight dimming.
758</p>
759
760<p> 808</p>
809
810</body>
811</section>
812<section>
813<title>Standby settings</title>
814<body>
815
816<p>
761First thing to check is the standby/suspend/off timings of the display. As this 817The first thing to check is the standby/suspend/off timings of the display. As
762depends heavily on your windowmanager, I'll let you figure it out yourself. 818this depends heavily on your windowmanager, I'll let you figure it out
763Just two common places: Blanking the terminal can be done with <c>setterm 819yourself. Just two common places: Blanking the terminal can be done with
764-blank &lt;number-of-minutesM&gt;</c>, <c>setterm -powersave on</c> and 820<c>setterm -blank &lt;number-of-minutesM&gt;</c>, <c>setterm -powersave on</c>
765<c>setterm -powerdown &lt;number-of-minutesM&gt;</c>. 821and <c>setterm -powerdown &lt;number-of-minutesM&gt;</c>. For X.org, modify
766For X.org, modify <path>/etc/X11/xorg.conf</path> similar to this: 822<path>/etc/X11/xorg.conf</path> similar to this:
767</p> 823</p>
768 824
769<pre caption="LCD suspend settings in X.org and XFree86"> 825<pre caption="LCD suspend settings in X.org">
770Section "ServerLayout" 826Section "ServerFlags"
771 Identifier [...]
772 [...]
773 Option "BlankTime" "5" <comment># Blank the screen after 5 minutes (Fake)</comment> 827 Option "blank time" "5" <comment># Blank the screen after 5 minutes (Fake)</comment>
774 Option "StandbyTime" "10" <comment># Turn off screen after 10 minutes (DPMS)</comment> 828 Option "standby time" "10" <comment># Turn off screen after 10 minutes (DPMS)</comment>
775 Option "SuspendTime" "20" <comment># Full suspend after 20 minutes</comment> 829 Option "suspend time" "20" <comment># Full suspend after 20 minutes</comment>
776 Option "OffTime" "30" <comment># Turn off after half an hour</comment> 830 Option "off time" "30" <comment># Turn off after half an hour</comment>
777 [...] 831 [...]
778EndSection 832EndSection
779 833
780[...] 834[...]
781 835
782Section "Monitor" 836Section "Monitor"
783 Identifier [...] 837 Identifier [...]
784 Option "DPMS" "true" 838 Option "DPMS"
785 [...] 839 [...]
786EndSection 840EndSection
787</pre> 841</pre>
788 842
789<p> 843</body>
790This is the same for XFree86 and <path>/etc/X11/XF86Config</path>. 844</section>
791</p> 845<section>
846<title>Backlight dimming</title>
847<body>
792 848
793<p> 849<p>
794Probably more important is the backlight dimming. If you have access to the 850Probably more important is the backlight dimming. If you have access to the
795dimming settings via a tool, write a small script that dims the backlight in 851dimming settings via a tool, write a small script that dims the backlight in
796battery mode and place it in your <e>battery</e> runlevel. The following script 852battery mode and place it in your <c>battery</c> runlevel. The following script
797should work on most IBM Thinkpads. It needs the <c>app-laptop/ibm-acpi</c> 853should work on most IBM Thinkpads and Toshiba laptops. You've got to enable the
798package or the appropriate option in your kernel has to be enabled. 854appropriate option in your kernel (IBM Thinkpads only). For Toshiba laptops,
855install <c>sys-power/acpitool</c> and skip configuration of <c>thinkpad_acpi</c>
856(formerly called <c>ibm_acpi</c>) as described below.
799</p> 857</p>
800 858
801<warn> 859<warn>
802Support for setting brightness is marked experimental in ibm-acpi. It accesses 860Support for setting brightness is marked experimental in thinkpad_acpi. It
803hardware directly and may cause severe harm to your system. Please read the 861accesses hardware directly and may cause severe harm to your system. Please
804<uri link="http://ibm-acpi.sourceforge.net/">ibm-acpi website</uri> 862read the <uri link="http://ibm-acpi.sourceforge.net/">thinkpad_acpi
863website</uri>
805</warn> 864</warn>
806 865
807<p> 866<p>
808To be able to set the brightness level, the ibm_acpi module has to be loaded 867To be able to set the brightness level, the thinkpad_acpi module has to be
809with the experimental parameter. 868loaded with the experimental parameter.
810</p> 869</p>
811 870
812<pre caption="automatically loading the ibm_acpi module"> 871<pre caption="automatically loading the thinkpad_acpi module">
813<comment>(Please read the warnings above before doing this!)</comment> 872<comment>(Please read the warnings above before doing this!)</comment>
814<i># emerge ibm-acpi</i>
815<i># echo "options ibm_acpi experimental=1" >> /etc/modules.d/ibm_acpi</i> 873# <i>echo "options thinkpad_acpi experimental=1" >> /etc/modprobe.d/thinkpad_acpi</i>
816<i># /sbin/modules-update</i> 874# <i>update-modules</i>
817<i># echo ibm_acpi >> /etc/modules.autoload.d/kernel-2.6</i> 875# <i>echo thinkpad_acpi >> /etc/modules.autoload.d/kernel-2.6</i>
818<i># modprobe ibm_acpi</i> 876# <i>modprobe thinkpad_acpi</i>
819</pre> 877</pre>
820 878
821<p> 879<p>
822This should work without error messages and a file 880This should work without error messages and a file
823<path>/proc/acpi/ibm/brightness</path> should be created after loading the 881<path>/proc/acpi/ibm/brightness</path> should be created after loading the
824module. An init script will take care of choosing the brightness according 882module. An init script will take care of choosing the brightness according to
825to the power source. 883the power source.
826</p> 884</p>
827 885
828<pre caption="/etc/conf.d/lcd-brightness"> 886<pre caption="/etc/conf.d/lcd-brightness">
829<comment># See /proc/acpi/ibm/brightness for available values</comment> 887<comment># See /proc/acpi/ibm/brightness for available values</comment>
830<comment># Please read /usr/share/doc/ibm-acpi-*/README.gz</comment> 888<comment># Please read /usr/src/linux/Documentation/thinkpad-acpi.txt</comment>
831 889
832<comment># brigthness level in ac mode. Default is 7.</comment> 890<comment># brightness level in ac mode. Default is 7.</comment>
833BRIGHTNESS_AC=7 891BRIGHTNESS_AC=7
834 892
835<comment># brightness level in battery mode. Default is 4.</comment> 893<comment># brightness level in battery mode. Default is 4.</comment>
836BRIGHTNESS_BATTERY=4 894BRIGHTNESS_BATTERY=4
837</pre> 895</pre>
850 if [ -f /proc/acpi/ibm/brightness ] 908 if [ -f /proc/acpi/ibm/brightness ]
851 then 909 then
852 ebegin "Setting LCD brightness" 910 ebegin "Setting LCD brightness"
853 echo "level ${LEVEL}" > /proc/acpi/ibm/brightness 911 echo "level ${LEVEL}" > /proc/acpi/ibm/brightness
854 eend $? 912 eend $?
913 elif [[ -e /usr/bin/acpitool &amp;&amp; -n $(acpitool -T | grep "LCD brightness") ]]
914 then
915 ebegin "Setting LCD brightness"
916 acpitool -l $LEVEL >/dev/null || ewarn "Unable to set lcd brightness"
917 eend $?
855 else 918 else
856 ewarn "Setting LCD brightness is not supported." 919 ewarn "Setting LCD brightness is not supported."
857 ewarn "Check that ibm_acpi is loaded into the kernel" 920 ewarn "For IBM Thinkpads, check that thinkpad_acpi is loaded into the kernel"
921 ewarn "For Toshiba laptops, you've got to install sys-power/acpitool"
858 fi 922 fi
859} 923}
860 924
861start() { 925start() {
862 set_brightness 926 set_brightness
871When done, make sure brightness is adjusted automatically by adding it to the 935When done, make sure brightness is adjusted automatically by adding it to the
872battery runlevel. 936battery runlevel.
873</p> 937</p>
874 938
875<pre caption="Enabling automatic brightness adjustment"> 939<pre caption="Enabling automatic brightness adjustment">
876<i># chmod +x /etc/init.d/lcd-brightness</i> 940# <i>chmod +x /etc/init.d/lcd-brightness</i>
877<i># rc-update add lcd-brightness battery</i> 941# <i>rc-update add lcd-brightness battery</i>
878<i># rc</i> 942# <i>rc</i>
879</pre> 943</pre>
880 944
881</body> 945</body>
882</section> 946</section>
883</chapter> 947</chapter>
884 948
885<chapter> 949<chapter>
886<title>Disk Power Management</title> 950<title>Disk Power Management</title>
887<section> 951<section>
888<title>Sleep when idle</title> 952<body>
953
954<p>
955Hard disks consume less energy in sleep mode. Therefore it makes sense to
956activate power saving features whenever the hard disk is not used for a certain
957amount of time. I'll show you two alternative possibilities to do it. First,
958laptop-mode will save most energy due to several measures which prevent or at
959least delay write accesses. The drawback is that due to the delayed write
960accesses a power outage or kernel crash will be more dangerous for data loss.
961If you don't like this, you have to make sure that there are no processes which
962write to your hard disk frequently. Afterwards you can enable power saving
963features of your hard disk with <c>hdparm</c> as the second alternative.
964</p>
965
889<body> 966</body>
967</section>
968<section>
969<title>Increasing idle time - laptop-mode</title>
970<body>
890 971
891<p>
892Let's bring the hard disk to sleep as early as possible whenever it is not
893needed. I'll show you two possibilities to do it. First <c>cpudyn</c> supports
894Disk Power Management. Uncomment the lines in the "Disk Options" section in
895<path>/etc/conf.d/cpudyn</path>. To put your first disk to sleep after 60
896seconds of no activity, you would modify it like this:
897</p> 972<p>
898 973Recent 2.6 kernels include the so-called <c>laptop-mode</c>. When activated,
899<pre caption="Using cpudyn for disk standby"> 974dirty buffers are written to disk on read calls or after 10 minutes (instead of
900<comment>################################################ 97530 seconds). This minimizes the time the hard disk needs to be spun up.
901# DISK OPTIONS
902# (disabled by default)
903################################################
904
905#
906# Timeout to put the disk in standby mode if there was no
907# io during that period (in seconds)
908#
909</comment>
910TIMEOUT=60
911<comment>
912#
913# Specified disks to spindown (comma separated devices)
914#
915</comment>
916DISKS=/dev/hda
917</pre>
918
919<p> 976</p>
920The second possibility is using a small script and hdparm. Create 977
921<path>/etc/init.d/pm.hda</path> like this: 978<pre caption="Automated start of laptop-mode">
979# <i>emerge laptop-mode-tools</i>
980</pre>
981
922</p> 982<p>
983<c>laptop-mode-tools</c> has its configuration file in
984<path>/etc/laptop-mode/laptop-mode.conf</path>. Adjust it the way you like it,
985it's well commented. Run <c>rc-update add laptop_mode battery</c> to start it
986automatically.
987</p>
923 988
989<p>
990Recent versions (1.11 and later) of laptop-mode-tools include a new tool
991<c>lm-profiler</c>. It will monitor your system's disk usage and running
992network services and suggests to disable unneeded ones. You can either disable
993them through laptop-mode-tools builtin runlevel support (which will be reverted
994by Gentoo's <c>/sbin/rc</c>) or use your <c>default</c>/<c>battery</c>
995runlevels (recommended).
996</p>
997
998<pre caption="Sample output from running lm-profiler">
999# <i>lm-profiler</i>
1000Profiling session started.
1001Time remaining: 600 seconds
1002[4296896.602000] amarokapp
1003Time remaining: 599 seconds
1004[4296897.714000] sort
1005[4296897.970000] mv
1006Time remaining: 598 seconds
1007Time remaining: 597 seconds
1008[4296900.482000] reiserfs/0
1009</pre>
1010
1011<p>
1012After profiling your system for ten minutes, lm-profiler will present a list of
1013services which might have caused disk accesses during that time.
1014</p>
1015
1016<pre caption="lm-profiler suggests to disable some services">
1017Program: "atd"
1018Reason: standard recommendation (program may not be running)
1019Init script: /etc/init.d/atd (GUESSED)
1020
1021Do you want to disable this service in battery mode? [y/N]: <i>n</i>
1022</pre>
1023
1024<p>
1025To disable atd as suggested in the example above, you would run <c>rc-update
1026del atd battery</c>. Be careful not to disable services that are needed for
1027your system to run properly - <c>lm-profiler</c> is likely to generate some
1028false positives. Do not disable a service if you are unsure whether it's
1029needed.
1030</p>
1031
1032</body>
1033</section>
1034<section>
1035<title>Limiting Write Accesses</title>
1036<body>
1037
1038<p>
1039If you don't want to use laptop-mode, you must take special care to disable
1040services that write to your disk frequently - <c>syslogd</c> is a good
1041candidate, for example. You probably don't want to shut it down completely, but
1042it's possible to modify the config file so that "unnecessary" things don't get
1043logged and thus don't create disk traffic. <c>Cups</c> writes to disk
1044periodically, so consider shutting it down and only enable it manually when
1045needed.
1046</p>
1047
1048<pre caption="Disabling cups in battery mode">
1049# <i>rc-update del cupsd battery</i>
1050</pre>
1051
1052<p>
1053You can also use <c>lm-profiler</c> from laptop-mode-tools (see above) to find
1054services to disable. Once you eliminated all of them, go on with configuring
1055hdparm.
1056</p>
1057
1058</body>
1059</section>
1060<section>
1061<title>hdparm</title>
1062<body>
1063
1064<p>
1065The second possibility is using <c>hdparm</c>. Skip this if
1066you are using laptop-mode. Otherwise, edit <path>/etc/conf.d/hdparm</path> and
1067add the following values to your drive entries. This example assumes your hard
1068drive is called <b>hda</b>:
1069</p>
1070
924<pre caption="Using hdparm for disk standby"> 1071<pre caption="Using /etc/conf.d/hdparm for disk standby">
925#!/sbin/runscript 1072hda_args="-q -S12"
926
927depend() {
928 after hdparm
929}
930
931start() {
932 ebegin "Activating Power Management for Hard Drives"
933 hdparm -q -S12 /dev/hda
934 eend $?
935}
936
937stop () {
938 ebegin "Deactivating Power Management for Hard Drives"
939 hdparm -q -S253 /dev/hda
940 eend $?
941}
942</pre> 1073</pre>
943 1074
1075<p>
1076This will activate power management for your hard drive. If you ever want to
1077deactivate power management, you can edit <path>/etc/conf.d/hdparm</path> and
1078change the values to <c>-q -S0</c>, or just run <c>hdparm -q -S0 /dev/hda</c>.
944<p> 1079</p>
945See <c>man hdparm</c> for the options. If your script is ready, add it to the 1080
946battery runlevel. 1081<p>
1082See <c>man hdparm</c> for the options. Though you can always start <c>hdparm</c>
1083manually when you are on battery power by running <c>/etc/init.d/hdparm
1084start</c>, it's much easier to automate its startup and shutdown. To do so, add
1085<c>hdparm</c> to the battery runlevel so that it will automatically enable power
1086management.
947</p> 1087</p>
948 1088
949<pre caption="Automate disk standby settings"> 1089<pre caption="Automate disk standby settings">
950# <i>chmod +x /etc/init.d/pm.hda</i>
951# <i>/sbin/depscan.sh</i>
952# <i>rc-update add pm.hda battery</i> 1090# <i>rc-update add hdparm battery</i>
953</pre> 1091</pre>
954 1092
955<impo> 1093<impo>
956Be careful with sleep/spin down settings of your hard drive. Setting it to 1094Be careful with sleep/spin down settings of your hard drive. Setting it to
957small values might wear out your drive and lose warranty. 1095small values might wear out your drive and lose warranty.
958</impo> 1096</impo>
959 1097
960</body> 1098</body>
961</section> 1099</section>
962<section> 1100<section>
963<title>Increasing idle time - laptop-mode</title>
964<body>
965
966<p>
967Recent kernels (2.6.6 and greater, recent 2.4 ones and others with patches)
968include the so-called <e>laptop-mode</e>. When activated, dirty buffers are
969written to disk on read calls or after 10 minutes (instead of 30 seconds). This
970minimizes the time the hard disk needs to be spun up.
971</p>
972
973<pre caption="Automated start of laptop-mode">
974# <i>emerge laptop-mode-tools</i>
975</pre>
976
977<p>
978<c>laptop-mode-tools</c> has it's configuration file in
979<path>/etc/laptop-mode/laptop-mode.conf</path>. Adjust it the way you like it,
980it's well commented. Run <c>rc-update add laptop_mode battery</c> to start it
981automatically.
982</p>
983
984</body>
985</section>
986<section>
987<title>Other tricks</title> 1101<title>Other tricks</title>
988<body> 1102<body>
989
990<p>
991Besides putting your disk to sleep state as early as possible, it is a good
992idea to minimize disk accesses. Have a look at processes that write to your
993disk frequently - the syslogd is a good candidate. You probably don't want to
994shut it down completely, but it's possible to modify the config file so that
995"unnecessary" things don't get logged and thus don't create disk traffic. Cups
996writes to disk periodically, so consider shutting it down and only enable it
997manually when needed.
998</p>
999
1000<pre caption="Disabling cups in battery mode">
1001# <i>rc-update del cupsd battery</i>
1002</pre>
1003 1103
1004<p> 1104<p>
1005Another possibility is to deactivate swap in battery mode. Before writing a 1105Another possibility is to deactivate swap in battery mode. Before writing a
1006swapon/swapoff switcher, make sure there is enough RAM and swap isn't used 1106swapon/swapoff switcher, make sure there is enough RAM and swap isn't used
1007heavily, otherwise you'll be in big problems. 1107heavily, otherwise you'll be in big problems.
1008</p> 1108</p>
1009 1109
1010<p> 1110<p>
1011If you don't want to use laptop-mode, it's still possible to minimize disk 1111If you don't want to use laptop-mode, it's still possible to minimize disk
1012access by mounting certain directories as <e>tmpfs</e> - write accesses are not 1112access by mounting certain directories as <c>tmpfs</c> - write accesses are not
1013stored on a disk, but in main memory and get lost with unmounting. Often it's 1113stored on a disk, but in main memory and get lost with unmounting. Often it's
1014useful to mount <path>/tmp</path> like this - you don't have to pay special 1114useful to mount <path>/tmp</path> like this - you don't have to pay special
1015attention as it gets cleared on every reboot regardless whether it was mounted 1115attention as it gets cleared on every reboot regardless whether it was mounted
1016on disk or in RAM. Just make sure you have enough RAM and no program (like a 1116on disk or in RAM. Just make sure you have enough RAM and no program (like a
1017download client or compress utility) needs extraordinary much space in 1117download client or compress utility) needs extraordinary much space in
1023none /tmp tmpfs size=32m 0 0 1123none /tmp tmpfs size=32m 0 0
1024</pre> 1124</pre>
1025 1125
1026<warn> 1126<warn>
1027Pay attention to the size parameter and modify it for your system. If you're 1127Pay attention to the size parameter and modify it for your system. If you're
1028unsure, don't try this at all, it can become a perfomance bottleneck easily. In 1128unsure, don't try this at all, it can become a performance bottleneck easily. In
1029case you want to mount <path>/var/log</path> like this, make sure to merge the 1129case you want to mount <path>/var/log</path> like this, make sure to merge the
1030log files to disk before unmounting. They are essential. Don't attempt to mount 1130log files to disk before unmounting. They are essential. Don't attempt to mount
1031/var/tmp like this. Portage uses it for compiling... 1131<path>/var/tmp</path> like this. Portage uses it for compiling...
1032</warn> 1132</warn>
1033 1133
1034</body> 1134</body>
1035</section> 1135</section>
1036</chapter> 1136</chapter>
1037 1137
1038<chapter> 1138<chapter>
1039<title>Power Management for other devices</title> 1139<title>Power Management For Other Devices</title>
1040<section> 1140<section>
1041<title>Graphics cards</title> 1141<title>Graphics Cards</title>
1042<body> 1142<body>
1043 1143
1044<p> 1144<p>
1045In case you own an ATI graphics card supporting PowerPlay (dynamic clock 1145In case you own an ATI graphics card supporting PowerPlay (dynamic clock
1046scaling for the the graphics processing unit GPU), you can activate this 1146scaling for the graphics processing unit GPU), you can activate this
1047feature in X.org. Open <path>/etc/X11/xorg.conf</path> and add (or enable) 1147feature in X.org. Open <path>/etc/X11/xorg.conf</path> and add (or enable) the
1048the <c>DynamicClocks</c> option in the Device section. Please notice that 1148<c>DynamicClocks</c> option in the Device section. Please notice that this
1049this feature will lead to crashes on some systems. 1149feature will lead to crashes on some systems.
1050</p> 1150</p>
1051 1151
1052<pre caption="Enabling ATI PowerPlay support in X.org"> 1152<pre caption="Enabling ATI PowerPlay support in X.org">
1053Section "Device" 1153Section "Device"
1054[...] 1154[...]
1061<section> 1161<section>
1062<title>Wireless Power Management</title> 1162<title>Wireless Power Management</title>
1063<body> 1163<body>
1064 1164
1065<p> 1165<p>
1066Wireless LAN cards consume quite a few energy. Put them in Power Management 1166Wireless LAN cards consume quite a bit of energy. Put them in Power Management
1067mode in analogy to the pm.hda script. 1167mode just like your hard drives.
1068</p>
1069
1070<pre caption="WLAN Power Management automated">
1071#!/sbin/runscript
1072start() {
1073 ebegin "Activating Power Management for Wireless LAN"
1074 iwconfig wlan0 power on power max period 3
1075 eend $?
1076}
1077
1078stop () {
1079 ebegin "Deactivating Power Management for Wireless LAN"
1080 iwconfig wlan0 power off
1081 eend $?
1082}
1083</pre>
1084
1085<p> 1168</p>
1086Starting this script will put wlan0 in Power Management mode, going to sleep at 1169
1087the latest three seconds after no traffic. 1170<note>
1088Save it as <path>/etc/init.d/pm.wlan0</path> and add it to the battery runlevel 1171This script assumes your wireless interface is called <c>wlan0</c>; replace
1089like the disk script above. See <c>man iwconfig</c> for details and more 1172this with the actual name of your interface.
1090options. If your driver and access point support changing the beacon time, this 1173</note>
1091is a good starting point to save even more energy. 1174
1092</p> 1175<p>
1093 1176Add the following option to <path>/etc/conf.d/net</path> to automatically enable
1094<pre caption="Power Management for WLAN"> 1177power management for your wireless card:
1095# <i>chmod +x /etc/init.d/pm.wlan0</i>
1096# <i>/sbin/depscan.sh</i>
1097# <i>rc-update add pm.wlan0 battery</i>
1098</pre> 1178</p>
1179
1180<pre caption="Automated WLAN Power Management">
1181iwconfig_wlan0="power on"
1182</pre>
1183
1184<p>
1185See <c>man iwconfig</c> for details and more options like the period between
1186wakeups or timeout settings. If your driver and access point support changing
1187the beacon time, this is a good starting point to save even more energy.
1188</p>
1099 1189
1100</body> 1190</body>
1101</section> 1191</section>
1102<section> 1192<section>
1103<title>USB Power Management</title> 1193<title>USB Power Management</title>
1107There are two problems with USB devices regarding energy consumption: First, 1197There are two problems with USB devices regarding energy consumption: First,
1108devices like USB mice, digital cameras or USB sticks consume energy while 1198devices like USB mice, digital cameras or USB sticks consume energy while
1109plugged in. You cannot avoid this (nevertheless remove them in case they're not 1199plugged in. You cannot avoid this (nevertheless remove them in case they're not
1110needed). Second, when there are USB devices plugged in, the USB host controller 1200needed). Second, when there are USB devices plugged in, the USB host controller
1111periodically accesses the bus which in turn prevents the CPU from going into 1201periodically accesses the bus which in turn prevents the CPU from going into
1112sleep mode. The kernel offers an experimental option to enable suspension of 1202sleep mode. The kernel offers an experimental option to enable suspension of
1113USB devices through driver calls or one of the <path>power/state</path> files 1203USB devices through driver calls or one of the <path>power/state</path> files
1114in <path>/sys</path>. 1204in <path>/sys</path>.
1115</p> 1205</p>
1116 1206
1117<pre caption="Enabling USB suspend support in the kernel"> 1207<pre caption="Enabling USB suspend support in the kernel">
1124</body> 1214</body>
1125</section> 1215</section>
1126</chapter> 1216</chapter>
1127 1217
1128<chapter> 1218<chapter>
1129<title>Sleep states: sleep, standby, suspend to disk</title> 1219<title>Sleep States: sleep, standby, and suspend to disk</title>
1130<section> 1220<section>
1131<title>Overview</title>
1132<body> 1221<body>
1133 1222
1134<p> 1223<p>
1135ACPI defines different sleep states. The more important ones are 1224ACPI defines different sleep states. The more important ones are
1136</p> 1225</p>
1137 1226
1138<ul> 1227<ul>
1139 <li>S1 aka Standby</li> 1228 <li>S1 aka Standby</li>
1140 <li>S3 aka Suspend to RAM aka Sleep</li> 1229 <li>S3 aka Suspend to RAM aka Sleep</li>
1141 <li>S4 aka Suspend to Disk aka Hibernate</li> 1230 <li>S4 aka Suspend to Disk aka Hibernate</li>
1142</ul> 1231</ul>
1143 1232
1159</p> 1248</p>
1160 1249
1161<pre caption="Kernel configuration for the various suspend types"> 1250<pre caption="Kernel configuration for the various suspend types">
1162 Power Management Options ---&gt; 1251 Power Management Options ---&gt;
1163 [*] Power Management support 1252 [*] Power Management support
1164 ACPI (Advanced Configuration and Power Interface) Support ---&gt; 1253 [*] Suspend to RAM and standby
1165 [*] ACPI Support
1166 [*] Sleep States
1167</pre> 1254</pre>
1168 1255
1169<p> 1256<p>
1170Once your kernel is prepared like above, you can use the 1257Once your kernel is properly configured, you can use the
1171<c>hibernate-script</c> to activate suspend or sleep mode. Let's install that 1258<c>hibernate-script</c> to activate suspend or sleep mode. Let's install that
1172first. 1259first.
1173</p> 1260</p>
1174 1261
1175<pre caption="Installing the hibernate-script"> 1262<pre caption="Installing the hibernate-script">
1176<i># emerge hibernate-script</i> 1263# <i>emerge hibernate-script</i>
1177</pre> 1264</pre>
1178 1265
1179<p> 1266<p>
1180Some configuration has to be done in <path>/etc/hibernate</path> The default 1267Some configuration has to be done in <path>/etc/hibernate</path>. The default
1181package introduces two configuration files <path>hibernate.conf</path> and 1268package introduces a few configuration files for each sleep state. Options that
1182<path>ram.conf</path>. 1269are common to all suspend methods are placed in <path>common.conf</path>; make
1183</p> 1270sure this file is properly set up for your system.
1184
1185<p> 1271</p>
1186To configure sleep, edit <path>ram.conf</path> in <path>/etc/hibernate</path>. 1272
1187<c>UseSysfsPowerState mem</c> is already setup correctly, but you have to go
1188through the rest of the configuration file and set it up for your system. The
1189comments and option names will guide you. If you use nfs or samba shares over
1190the network, make sure to shutdown the appropriate init scripts to avoid
1191timeouts.
1192</p> 1273<p>
1274To configure sleep, edit <path>sysfs-ram.conf</path> in
1275<path>/etc/hibernate</path>. <c>UseSysfsPowerState mem</c> is already setup
1276correctly, but if you need to make further changes to this particular sleep
1277state (or any other sleep state) you should add them to
1278<path>/etc/hibernate/hibernate.conf</path>. The comments and option names will
1279guide you. If you use nfs or samba shares over the network, make sure to
1280shutdown the appropriate init scripts to avoid timeouts.
1281</p>
1282
1283<note>
1284For more information on setting up sleep states, read <c>man
1285hibernate.conf</c>.
1286</note>
1193 1287
1194<p> 1288<p>
1195Ready? Now is the last chance to backup any data you want to keep after 1289Ready? Now is the last chance to backup any data you want to keep after
1196executing the next command. Notice that you probably have to hit a special key 1290executing the next command. Notice that you probably have to hit a special key
1197like <e>Fn</e> to resume from sleep. 1291like <c>Fn</c> to resume from sleep.
1198</p> 1292</p>
1199 1293
1200<pre caption="Calling sleep"> 1294<pre caption="Calling sleep">
1201<i># hibernate-ram</i> 1295# <i>hibernate-ram</i>
1202</pre> 1296</pre>
1203 1297
1204<p> 1298<p>
1205If you're still reading, it seems to work. You can also setup standby (S1) in 1299If you're still reading, it seems to work. You can also setup standby (S1) in a
1206a similar way by copying <path>ram.conf</path> to <path>standby.conf</path> 1300similar way by editing <path>sysfs-ram.conf</path> and changing
1207and creating a symlink <path>/usr/sbin/hibernate-standby</path> pointing to 1301"UseSysfsPowerState mem" to "UseSysfsPowerState standby". S3 and S4 are the more
1208<path>/usr/sbin/hibernate</path>. S3 and S4 are the more interesting sleep
1209states due to greater energy savings however. 1302interesting sleep states due to greater energy savings however.
1210</p> 1303</p>
1211 1304
1212</body> 1305</body>
1213</section> 1306</section>
1214<section> 1307<section>
1227Shutdown any NFS or samba server/client before hibernating. 1320Shutdown any NFS or samba server/client before hibernating.
1228</warn> 1321</warn>
1229 1322
1230<p> 1323<p>
1231There are two different implementations for S4. The original one is swsusp, 1324There are two different implementations for S4. The original one is swsusp,
1232then there is the newer suspend2 with a nicer interface (including 1325then there is the newer tuxonice (formerly suspend2) with a nicer interface
1233fbsplash support). A <uri link="http://suspend2.net/features.html#compare"> 1326(including fbsplash support). A <uri
1234feature comparison</uri> is available at the <uri link="http://suspend2.net"> 1327link="http://tuxonice.net/features.html#compare">feature comparison</uri> is
1235suspend2 Homepage</uri>. There used to be Suspend-to-Disk (pmdisk), a fork of 1328available at the <uri link="http://www.tuxonice.net">tuxonice homepage</uri>.
1236swsusp, but it has been merged back. 1329There used to be Suspend-to-Disk (pmdisk), a fork of swsusp, but it has been
1237</p> 1330merged back.
1238
1239<p> 1331</p>
1332
1333<p>
1240Suspend2 is not included in the mainline kernel yet, therefore you either have 1334TuxOnIce is not included in the mainline kernel yet, therefore you either have
1241to patch your kernel sources with the patches provided by 1335to patch your kernel sources with the patches provided by <uri
1242<uri link="http://suspend2.net">suspend2.net</uri> or use 1336link="http://www.tuxonice.net">tuxonice.net</uri> or use
1243<c>sys-kernel/suspend2-sources</c>. 1337<c>sys-kernel/tuxonice-sources</c>.
1244</p>
1245
1246<p> 1338</p>
1339
1340<p>
1247The kernel part for both swusp and suspend2 is as follows: 1341The kernel part for both swusp and TuxOnIce is as follows:
1248</p> 1342</p>
1249 1343
1250<pre caption="Kernel configuration for the various suspend types"> 1344<pre caption="Kernel configuration for the various suspend types">
1251Power Management Options ---&gt; 1345Power Management support ---&gt;
1252 <comment>(hibernate with swsusp)</comment> 1346 <comment>(hibernate with swsusp)</comment>
1253 [*] Software Suspend 1347 [*] Hibernation (aka 'suspend to disk')
1254 <comment>(replace /dev/SWAP with your swap partition)</comment> 1348 <comment>(replace /dev/SWAP with your swap partition)</comment>
1255 (/dev/SWAP) Default resume partition 1349 (/dev/SWAP) Default resume partition
1256 1350
1257 <comment>(hibernate with suspend2)</comment> 1351 <comment>(hibernate with TuxOnIce)</comment>
1258 Software Suspend 2 1352 Enhanced Hibernation (TuxOnIce)
1259 --- Image Storage (you need at least one writer) 1353 --- Image Storage (you need at least one allocator)
1260 [*] File Writer 1354 [*] File Allocator
1261 [*] Swap Writer 1355 [*] Swap Allocator
1262 --- General Options 1356 --- General Options
1263 [*] LZF image compression 1357 [*] Compression support
1264 <comment>(replace /dev/SWAP with your swap partition)</comment>
1265 (swap:/dev/SWAP) Default resume device name
1266 [ ] Allow Keep Image Mode 1358 [ ] Allow Keep Image Mode
1359 [*] Replace swsusp by default
1267</pre> 1360</pre>
1268 1361
1269<p> 1362<p>
1270The configuration for swsusp is rather easy. If you didn't store the location 1363The configuration for swsusp is rather easy. If you didn't store the location
1271of your swap partition in the kernel config, you can also pass it as a 1364of your swap partition in the kernel config, you can also pass it as a
1272parameter with the <c>resume=/dev/SWAP</c> directive. If booting is not 1365parameter with the <c>resume=/dev/SWAP</c> directive. If booting is not
1273possible due to a broken image, use the <c>noresume</c> kernel parameter. The 1366possible due to a broken image, use the <c>noresume</c> kernel parameter. The
1274<c>hibernate-cleanup</c> init script invalidates swsusp images during the 1367<c>hibernate-cleanup</c> init script invalidates swsusp images during the boot
1275boot process. 1368process.
1276</p> 1369</p>
1277 1370
1278<pre caption="Invalidating swsusp images during the boot process"> 1371<pre caption="Invalidating swsusp images during the boot process">
1279<i># rc-update add hibernate-cleanup boot</i> 1372# <i>rc-update add hibernate-cleanup boot</i>
1280</pre> 1373</pre>
1281 1374
1282<p> 1375<p>
1283To activate hibernate with swsusp, use the hibernate script and set 1376To activate hibernate with swsusp, use the hibernate script and set
1284<c>UseSysfsPowerState disk</c> in <path>/etc/hibernate/hibernate.conf</path>. 1377<c>UseSysfsPowerState disk</c> in <path>/etc/hibernate/sysfs-disk</path>.
1285</p> 1378</p>
1286 1379
1287<warn> 1380<warn>
1288Backup your data before doing this. Run <c>sync</c> before executing one of the 1381Backup your data before doing this. Run <c>sync</c> before executing one of the
1289commands to have cached data written to disk. First try it outside of X, then 1382commands to have cached data written to disk. First try it outside of X, then
1290with X running, but not logged in. 1383with X running, but not logged in.
1291</warn> 1384</warn>
1292 1385
1293<p> 1386<p>
1294If you experience kernel panics due to uhci or similar, try to compile USB 1387If you experience kernel panics due to uhci or similar, try to compile USB
1295support as module and unload the modules before sending your laptop to sleep 1388support as module and unload the modules before sending your laptop to sleep
1296mode. There are configuration options for this in <path>hibernate.conf</path> 1389mode. There are configuration options for this in <path>common.conf</path>
1297</p> 1390</p>
1298 1391
1299<pre caption="Hibernating with swsusp"> 1392<pre caption="Hibernating with swsusp">
1300<i># nano -w /etc/hibernate.conf</i> 1393# <i>nano -w /etc/hibernate/common.conf</i>
1301<comment>(Make sure you have a backup of your data)</comment> 1394<comment>(Make sure you have a backup of your data)</comment>
1302<i># hibernate</i> 1395# <i>hibernate</i>
1303</pre> 1396</pre>
1304 1397
1305<p> 1398<p>
1306The following section discusses the setup of suspend2 including fbsplash 1399The following section discusses the setup of TuxOnIce including fbsplash support
1307support for a nice graphical progress bar during suspend and resume. 1400for a nice graphical progress bar during suspend and resume.
1308</p>
1309
1310<p> 1401</p>
1402
1403<p>
1311The first part of the configuration is similar to the configuration of 1404The first part of the configuration is similar to the configuration of swsusp.
1312swsusp. In case you didn't store the location of your swap partition in the 1405In case you didn't store the location of your swap partition in the kernel
1313kernel config, you have to pass it as a kernel parameter with the 1406config, you have to pass it as a kernel parameter with the
1314<c>resume2=swap:/dev/SWAP</c> directive. If booting is not possible due to a 1407<c>resume=swap:/dev/SWAP</c> directive. If booting is not possible due to a
1315broken image, append the <c>noresume2</c> parameter. Additionally, the 1408broken image, append the <c>noresume</c> parameter. Additionally, the
1316<c>hibernate-cleanup</c> init script invalidates suspend2 images during the 1409<c>hibernate-cleanup</c> init script invalidates TuxOnIce images during the boot
1317boot process. 1410process.
1318</p> 1411</p>
1319 1412
1320<pre caption="Invalidating suspend2 images during the boot process"> 1413<pre caption="Invalidating TuxOnIce images during the boot process">
1321<i># rc-update add hibernate-cleanup boot</i> 1414# <i>rc-update add hibernate-cleanup boot</i>
1322</pre> 1415</pre>
1323 1416
1324<p>Now edit <path>/etc/hibernate/hibernate.conf</path>, enable the
1325<e>suspend2</e> section and comment everything in the <e>sysfs_power_state</e>
1326and <e>acpi_sleep</e> sections. Do not enable the fbsplash part in global
1327options yet.
1328</p> 1417<p>
1418Now edit <path>/etc/hibernate/tuxonice.conf</path>, enable the <c>TuxOnIce</c>
1419options you need. Do not enable the <c>fbsplash</c> options in
1420<c>common.conf</c> just yet.
1421</p>
1329 1422
1330<pre caption="Hibernating with suspend2"> 1423<pre caption="Hibernating with TuxOnIce">
1331<i># nano -w /etc/hibernate.conf</i> 1424# <i>nano -w /etc/hibernate/tuxonice.conf</i>
1332<comment>(Make sure you have a backup of your data)</comment> 1425<comment>(Make sure you have a backup of your data)</comment>
1333<i># hibernate</i> 1426# <i>hibernate</i>
1334</pre> 1427</pre>
1335 1428
1336<p> 1429<p>
1337Please configure fbsplash now if you didn't do already. To enable fbsplash 1430Please configure <c>fbsplash</c> now if you didn't do already. To enable
1338support during hibernation, the <c>sys-apps/suspend2-userui</c> package is 1431fbsplash support during hibernation, the <c>sys-apps/tuxonice-userui</c> package
1339needed. Additionally, you've got to enable the <e>fbsplash</e> USE flag. 1432is needed. Additionally, you've got to enable the <c>fbsplash</c> USE flag.
1340</p> 1433</p>
1341 1434
1342<pre caption="Installing suspend2-userui"> 1435<pre caption="Installing tuxonice-userui">
1343<i># mkdir -p /etc/portage</i>
1344<i># echo sys-apps/suspend2-userui fbsplash >> /etc/portage/package.use</i> 1436# <i>echo "sys-apps/tuxonice-userui fbsplash" >> /etc/portage/package.use</i>
1345<i># emerge suspend2-userui</i> 1437<comment>(It may be marked ~arch, so first it must be keyworded)</comment>
1438# <i>echo "sys-apps/tuxonice-userui" >> /etc/portage/package.keywords</i>
1439# <i>emerge tuxonice-userui</i>
1346</pre> 1440</pre>
1347 1441
1348<p> 1442<p>
1349The ebuild tells you to make a symlink to the theme you want to use. For 1443The ebuild tells you to make a symlink to the theme you want to use. For
1350example, to use the <c>livecd-2005.1</c> theme, run the following command: 1444example, to use the <c>livecd-2005.1</c> theme, run the following command:
1351</p> 1445</p>
1352 1446
1353<pre caption="Using the livecd-2005.1 theme during hibernation"> 1447<pre caption="Using the livecd-2005.1 theme during hibernation">
1354<i># ln -sfn /etc/splash/livecd-2005.1 /etc/splash/suspend2</i> 1448# <i>ln -sfn /etc/splash/livecd-2005.1 /etc/splash/tuxonice</i>
1355</pre> 1449</pre>
1356 1450
1357<p> 1451<p>
1358If you don't want a black screen in the first part of the resume process, you 1452If you don't want a black screen in the first part of the resume process, you
1359have to add the <c>suspend2ui_fbsplash</c> tool to your initrd image. Assuming 1453have to add the <c>tuxoniceui_fbsplash</c> tool to your initrd image. Assuming
1360you created the initrd image with <c>splash_geninitramfs</c> and saved it as 1454you created the initrd image with <c>splash_geninitramfs</c> and saved it as
1361<path>/boot/fbsplash-emergence-1024x768</path>, here's how to do 1455<path>/boot/fbsplash-emergence-1024x768</path>, here's how to do that.
1362that.
1363</p> 1456</p>
1364 1457
1365<pre caption="Adding suspend2ui_fbsplash to an initrd image"> 1458<pre caption="Adding tuxoniceui_fbsplash to an initrd image">
1366<i># mount /boot</i> 1459# <i>mount /boot</i>
1367<i># mkdir ~/initrd.d</i> 1460# <i>mkdir ~/initrd.d</i>
1368<i># cp /boot/fbsplash-emergence-1024x768 ~/initrd.d/</i> 1461# <i>cp /boot/fbsplash-emergence-1024x768 ~/initrd.d/</i>
1369<i># cd ~/initrd.d</i> 1462# <i>cd ~/initrd.d</i>
1370<i># gunzip -c fbsplash-emergence-1024x768 | cpio -idm --quiet -H newc</i> 1463# <i>gunzip -c fbsplash-emergence-1024x768 | cpio -idm --quiet -H newc</i>
1371<i># rm fbsplash-emergence-1024x768</i> 1464# <i>rm fbsplash-emergence-1024x768</i>
1372<i># cp /usr/sbin/suspend2ui_fbsplash sbin/</i> 1465# <i>cp /usr/sbin/tuxoniceui_fbsplash sbin/</i>
1373<i># find . | cpio --quiet --dereference -o -H newc | gzip -9 > /boot/fbsplash-suspend2-emergence-1024x768</i> 1466# <i>find . | cpio --quiet --dereference -o -H newc | gzip -9 > /boot/fbsplash-tuxonice-emergence-1024x768</i>
1374</pre> 1467</pre>
1375 1468
1376<p> 1469<p>
1377Afterwards adjust <path>grub.conf</path> respectively <path>lilo.conf</path> 1470Afterwards adjust <path>grub.conf</path> (or <path>lilo.conf</path>) so that
1378so that your suspend2 kernel uses 1471your TuxOnIce kernel uses
1379<path>/boot/fbsplash-suspend2-emergence-1024x768</path> as initrd image. You 1472<path>/boot/fbsplash-tuxonice-emergence-1024x768</path> as initrd image. You can
1380can now test a dry run to see if everything is setup correctly. 1473now test a dry run to see if everything is setup correctly.
1381</p> 1474</p>
1382 1475
1383<pre caption="Test run for fbsplash hibernation"> 1476<pre caption="Test run for fbsplash hibernation">
1384<i># suspend2ui_fbsplash -t</i> 1477# <i>tuxoniceui_fbsplash -t</i>
1385</pre> 1478</pre>
1386 1479
1387<p> 1480<p>
1388Afterwards open <path>/etc/hibernate/hibernate.conf</path> again and activate 1481Afterwards open <path>/etc/hibernate/common.conf</path> and activate the
1389the fbsplash options. Execute <c>hibernate</c> and enjoy. 1482fbsplash options. Execute <c>hibernate</c> and enjoy.
1390</p> 1483</p>
1391 1484
1392</body> 1485</body>
1393</section> 1486</section>
1394</chapter> 1487</chapter>
1395 1488
1396<chapter> 1489<chapter>
1397<title>Troubleshooting</title> 1490<title>Troubleshooting</title>
1398<section> 1491<section>
1399<title>If things go wrong...</title>
1400<body> 1492<body>
1401 1493
1402<p> 1494<p>
1403<e>Q:</e> I'm trying to change the CPU frequency, but 1495<e>Q:</e> I'm trying to change the CPU frequency, but
1404<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor</path> does not 1496<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor</path> does not
1406</p> 1498</p>
1407 1499
1408<p> 1500<p>
1409<e>A:</e> Make sure your processor supports CPU frequency scaling and you chose 1501<e>A:</e> Make sure your processor supports CPU frequency scaling and you chose
1410the right CPUFreq driver for your processor. Here is a list of processors that 1502the right CPUFreq driver for your processor. Here is a list of processors that
1411are supported by cpufreq (kernel 2.6.7): ARM Integrator, ARM-SA1100, 1503are supported by cpufreq (kernel 2.6.7): ARM Integrator, ARM-SA1100, ARM-SA1110,
1412ARM-SA1110, AMD Elan - SC400, SC410, AMD mobile K6-2+, AMD mobile K6-3+, AMD 1504AMD Elan - SC400, SC410, AMD mobile K6-2+, AMD mobile K6-3+, AMD mobile Duron,
1413mobile Duron, AMD mobile Athlon, AMD Opteron, AMD Athlon 64, Cyrix Media GXm, 1505AMD mobile Athlon, AMD Opteron, AMD Athlon 64, Cyrix Media GXm, Intel mobile
1414Intel mobile PIII and Intel mobile PIII-M on certain chipsets, Intel Pentium 4, 1506PIII and Intel mobile PIII-M on certain chipsets, Intel Pentium 4, Intel Xeon,
1415Intel Xeon, Intel Pentium M (Centrino), National Semiconductors Geode GX, 1507Intel Pentium M (Centrino), National Semiconductors Geode GX, Transmeta Crusoe,
1416Transmeta Crusoe, VIA Cyrix 3 / C3, UltraSPARC-III, SuperH SH-3, SH-4, several 1508VIA Cyrix 3 / C3, UltraSPARC-III, SuperH SH-3, SH-4, several "PowerBook" and
1417"PowerBook" and "iBook2" and various processors on some ACPI 2.0-compatible 1509"iBook2" and various processors on some ACPI 2.0-compatible systems (only if
1418systems (only if "ACPI Processor Performance States" are available to the 1510"ACPI Processor Performance States" are available to the ACPI/BIOS interface).
1419ACPI/BIOS interface).
1420</p> 1511</p>
1421 1512
1422<p> 1513<p>
1423<e>Q:</e> My laptop supports frequency scaling, but 1514<e>Q:</e> My laptop supports frequency scaling, but
1424<path>/sys/devices/system/cpu/cpu0/cpufreq/</path> is empty. 1515<path>/sys/devices/system/cpu/cpu0/cpufreq/</path> is empty.
1429Try to update the BIOS, especially if a broken DSDT is reported. You can also 1520Try to update the BIOS, especially if a broken DSDT is reported. You can also
1430try to fix it yourself (which is beyond the scope of this guide). 1521try to fix it yourself (which is beyond the scope of this guide).
1431</p> 1522</p>
1432 1523
1433<p> 1524<p>
1434<e>Q:</e> My laptop supports frequency scaling, but according to /proc/cpuinfo 1525<e>Q:</e> My laptop supports frequency scaling, but according to
1435the speed never changes. 1526<path>/proc/cpuinfo</path> the speed never changes.
1436</p> 1527</p>
1437 1528
1438<p> 1529<p>
1439<e>A:</e> Probably you have activated symmetric multiprocessing support 1530<e>A:</e> Probably you have activated symmetric multiprocessing support
1440(CONFIG_SMP) in your kernel. Deactivate it and it should work. Some older 1531(CONFIG_SMP) in your kernel. Deactivate it and it should work. Some older
1441kernels had a bug causing this. In that case, run <c>emerge x86info</c>, 1532kernels had a bug causing this. In that case, run <c>emerge x86info</c>, update
1442update your kernel as asked and check the current frequency with 1533your kernel as asked and check the current frequency with <c>x86info -mhz</c>.
1443<c>x86info -mhz</c>.
1444</p> 1534</p>
1445 1535
1446<p> 1536<p>
1447<e>Q:</e> I can change the CPU frequency, but the range is not as wide as in 1537<e>Q:</e> I can change the CPU frequency, but the range is not as wide as in
1448another OS. 1538another OS.
1449</p> 1539</p>
1450 1540
1451<p> 1541<p>
1452<e>A:</e> You can combine frequency scaling with ACPI throttling to get a lower 1542<e>A:</e> You can combine frequency scaling with ACPI throttling to get a lower
1453minimum frequency. Notice that throttling doesn't save much energy and is 1543minimum frequency. Notice that throttling doesn't save much energy and is mainly
1454mainly used for thermal management (keeping your laptop cool and quiet). You 1544used for thermal management (keeping your laptop cool and quiet). You can read
1455can read the current throttling state with <c>cat 1545the current throttling state with <c>cat /proc/acpi/processor/CPU/throttling</c>
1456/proc/acpi/processor/CPU/throttling</c> and change it with <c>echo -n "0:x" > 1546and change it with <c>echo -n "0:x" > /proc/acpi/processor/CPU/limit</c>, where
1457/proc/acpi/processor/CPU/limit</c>, where x is one of the Tx states listed in 1547x is one of the Tx states listed in
1458<path>/proc/acpi/processor/CPU/throttling</path>. 1548<path>/proc/acpi/processor/CPU/throttling</path>.
1459</p> 1549</p>
1460 1550
1461<p> 1551<p>
1462<e>Q:</e> When configuring the kernel, powersave, performance and userspace 1552<e>Q:</e> When configuring the kernel, powersave, performance and userspace
1486<e>A:</e> Check that battery support is compiled into your kernel. If you use 1576<e>A:</e> Check that battery support is compiled into your kernel. If you use
1487it as a module, make sure the module is loaded. 1577it as a module, make sure the module is loaded.
1488</p> 1578</p>
1489 1579
1490<p> 1580<p>
1581<e>Q:</e> My system logger reports things like "logger: ACPI group battery /
1582action battery is not defined".
1583</p>
1584
1585<p>
1586<e>A:</e> This message is generated by the <path>/etc/acpi/default.sh</path>
1587script that is shipped with acpid. You can safely ignore it. If you like to get
1588rid of it, you can comment the appropriate line in
1589<path>/etc/acpi/default.sh</path> as shown below:
1590</p>
1591
1592<pre caption="Disabling warnings about unknown acpi events">
1593 *) # logger "ACPI action $action is not defined"
1594</pre>
1595
1596<p>
1491<e>Q:</e> I have a Dell Inspiron 51XX and I don't get any ACPI events. 1597<e>Q:</e> I have a Dell Inspiron 51XX and I don't get any ACPI events.
1492</p> 1598</p>
1493 1599
1494<p> 1600<p>
1495<e>A:</e> This seems to be a kernel bug. Read on <uri 1601<e>A:</e> This seems to be a kernel bug. Read on <uri
1496link="http://bugme.osdl.org/show_bug.cgi?id=1752">here</uri>. 1602link="http://bugme.osdl.org/show_bug.cgi?id=1752">here</uri>.
1497</p> 1603</p>
1498 1604
1499<p> 1605<p>
1500<e>Q:</e> I activated the DynamicClocks option in <path>xorg.conf</path> and 1606<e>Q:</e> I activated the <c>DynamicClocks</c> option in <path>xorg.conf</path>
1501now X.org crashes / the screen stays black / my laptop doesn't shutdown 1607and now X.org crashes / the screen stays black / my laptop doesn't shutdown
1502properly. 1608properly.
1503</p> 1609</p>
1504 1610
1505<p> 1611<p>
1506<e>A:</e> This happens on some systems. You have to disable DynamicClocks. 1612<e>A:</e> This happens on some systems. You have to disable
1507</p> 1613<c>DynamicClocks</c>.
1508
1509<p> 1614</p>
1615
1616<p>
1510<e>Q:</e> I want to use suspend2, but it tells me my swap partition is too 1617<e>Q:</e> I want to use TuxOnIce, but it tells me my swap partition is too
1511small. Resizing is not an option. 1618small. Resizing is not an option.
1512</p> 1619</p>
1513 1620
1514<p> 1621<p>
1515<e>A:</e> If there is enough free space on your system, you can use the 1622<e>A:</e> If there is enough free space on your system, you can use the
1516filewriter instead of the swapwriter. The <c>hibernate-script</c> supports it 1623filewriter instead of the swapwriter. The <c>hibernate-script</c> supports it as
1517as well. More information can be found in 1624well. More information can be found in
1518<path>/usr/src/linux/Documentation/power/suspend2.txt</path>. 1625<path>/usr/src/linux/Documentation/power/tuxonice.txt</path>.
1519</p> 1626</p>
1520 1627
1521<p> 1628<p>
1522<e>Q:</e> I just bought a brand new battery, but it only lasts for some 1629<e>Q:</e> I just bought a brand new battery, but it only lasts for some
1523minutes! What am I doing wrong? 1630minutes! What am I doing wrong?
1524</p> 1631</p>
1525 1632
1526<p> 1633<p>
1527<e>A:</e> First follow your manufacturer's advice on how to charge the battery 1634<e>A:</e> First follow your manufacturer's advice on how to charge the battery
1528correctly. 1635correctly.
1529</p> 1636</p>
1530 1637
1531<p> 1638<p>
1532<e>Q:</e> The above didn't help. What should I do then? 1639<e>Q:</e> The above didn't help. What should I do then?
1533</p> 1640</p>
1550<p> 1657<p>
1551<e>Q:</e> My problem is not listed above. Where should I go next? 1658<e>Q:</e> My problem is not listed above. Where should I go next?
1552</p> 1659</p>
1553 1660
1554<p> 1661<p>
1555<e>A:</e> Don't fear to contact me, <mail link="fragfred@gmx.de">Dennis 1662<e>A:</e> Don't fear to contact me, <mail link="earthwings@gentoo.org">Dennis
1556Nienhüser</mail>, directly. 1663Nienhüser</mail>, directly. The <uri link="http://forums.gentoo.org">Gentoo
1664Forums</uri> are a good place to get help as well. If you prefer IRC, try the
1665<c>#gentoo-laptop</c> <uri link="irc://irc.gentoo.org">channel</uri>.
1557</p> 1666</p>
1558 1667
1559</body> 1668</body>
1560</section> 1669</section>
1561</chapter> 1670</chapter>

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