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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 1.14 2005/06/10 18:45:21 swift Exp $ --> 3<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/power-management-guide.xml,v 1.21 2006/08/17 00:45:29 rane Exp $ -->
4<guide link="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>
9</author> 12</author>
10 13
11<abstract> 14<abstract>
12Power Management is the key to extend battery run time on mobile systems like 15Power Management is the key to extend battery run time on mobile systems like
13laptops. This guide assists you setting it up on your laptop. 16laptops. This guide assists you setting it up on your laptop.
14</abstract> 17</abstract>
15 18
16<!-- The content of this document is licensed under the CC-BY-SA license --> 19<!-- The content of this document is licensed under the CC-BY-SA license -->
17<!-- See http://creativecommons.org/licenses/by-sa/2.0 --> 20<!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
18<license/> 21<license/>
19 22
20<version>1.24</version> 23<version>1.28</version>
21<date>2005-06-10</date> 24<date>2006-07-26</date>
22 25
23<chapter> 26<chapter>
24<title>Introduction</title> 27<title>Introduction</title>
25<section> 28<section>
26<title>Why Power Management?</title>
27<body> 29<body>
28 30
29<p> 31<p>
30Capacity and lifetime of laptop batteries has improved much in the last years. 32Capacity and lifetime of laptop batteries have improved much in the last years.
31Nevertheless modern processors consume much more energy than older ones and 33Nevertheless modern processors consume much more energy than older ones and
32each laptop generation introduces more devices hungry for energy. That's why 34each laptop generation introduces more devices hungry for energy. That's why
33Power Management is more important than ever. Increasing battery run time 35Power Management is more important than ever. Increasing battery run time
34doesn't necessarily mean buying another battery. Much can be achieved applying 36doesn't necessarily mean buying another battery. Much can be achieved applying
35intelligent Power Management policies. 37intelligent Power Management policies.
36</p> 38</p>
37 39
38</body> 40</body>
39</section> 41</section>
40
41<section> 42<section>
42<title>A quick overview</title> 43<title>A Quick Overview</title>
43<body> 44<body>
44 45
45<p> 46<p>
46Please notice that this guide describes Power Management for <e>laptops</e>. 47Please 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 48While 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 54As this guide has become rather long, here's a short overview helping you to
54find your way through it. 55find your way through it.
55</p> 56</p>
56 57
57<p> 58<p>
58The <e>Prerequisites</e> chapter talks about some requirements that should be 59The <uri link="#doc_chap2">Prerequisites</uri> chapter talks about some
59met before any of the following device individual sections will work. This 60requirements that should be met before any of the following device individual
60includes BIOS settings, kernel configuration and some simplifications in user 61sections will work. This includes BIOS settings, kernel configuration and some
61land. The following three chapters focus on devices that typically consume most 62simplifications in user land. The following three chapters focus on devices
62energy - processor, display and hard drive. Each can be configured seperately. 63that typically consume most energy - processor, display and hard drive. Each
63<e>CPU Power Management</e> shows how to adjust the processor's frequency to 64can be configured seperately. <uri link="#doc_chap3">CPU Power Management</uri>
64save a maximum of energy whithout losing too much performance. A few different 65shows how to adjust the processor's frequency to save a maximum of energy
65tricks prevent your hard drive from working unnecessarily often in <e>Disk Power 66without losing too much performance. A few different tricks prevent your hard
67drive from working unnecessarily often in <uri link="#doc_chap5">Disk Power
66Management</e> (decreasing noise level as a nice side effect). Some notes on 68Management</uri> (decreasing noise level as a nice side effect). Some notes on
67Wireless LAN and USB finish the device section in <e>Power Management for other 69graphics cards, Wireless LAN and USB finish the device section in <uri
68devices</e> while another chapter is dedicated to the (rather experimental) 70link="#doc_chap6">Power Management For Other Devices</uri> while another
69<e>sleep states</e>. Last not least <e>Troubleshooting</e> lists common 71chapter is dedicated to the (rather experimental) <uri link="#doc_chap7">sleep
70pitfalls. 72states</uri>. Last not least <uri link="#doc_chap8">Troubleshooting</uri> lists
73common pitfalls.
71</p> 74</p>
72 75
73</body> 76</body>
74</section>
75
76<section> 77</section>
78<section>
77<title>Power Budget for each component</title> 79<title>Power Budget For Each Component</title>
78<body> 80<body>
79 81
80<figure link="/images/energy-budget.png" short="Which component consumes how 82<figure link="/images/energy-budget.png" short="Which component consumes how
81much energy?" caption="Power budget for each component"/> 83much energy?" caption="Power budget for each component"/>
82 84
93</chapter> 95</chapter>
94 96
95<chapter> 97<chapter>
96<title>Prerequisites</title> 98<title>Prerequisites</title>
97<section> 99<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> 100<body>
112</section> 101
102<p>
103Before discussing the details of making individual devices Power Management
104aware, make sure certain requirements are met. After controlling BIOS settings,
105some kernel options want to be enabled - these are in short ACPI, sleep states
106and CPU frequency scaling. As power saving most of the time comes along with
107performance loss or increased latency, it should only be enabled when running
108on batteries. That's where a new runlevel <e>battery</e> comes in handy.
109</p>
110
111</body>
113<section> 112</section>
113<section>
114<title>The BIOS part</title> 114<title>The BIOS Part</title>
115<body> 115<body>
116 116
117<p> 117<p>
118First have a look into your BIOS Power Management settings. The best way is to 118First 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 119combine BIOS and operating system policies, but for the moment it's better to
123</p> 123</p>
124 124
125</body> 125</body>
126</section> 126</section>
127<section> 127<section>
128<title>Setting USE Flags</title>
129<body>
130
131<p>
132Please check that the <c>acpi</c> USE flag is set in
133<path>/etc/make.conf</path>. Other USE flags that might be interesting for your
134system are <c>apm</c>, <c>lm_sensors</c>, <c>nforce2</c>, <c>nvidia</c>,
135<c>pmu</c>. See <path>/usr/portage/profiles/use*.desc</path> for details. If
136you forgot to set one of these flags, you can recompile affected packages using
137the <c>--newuse</c> flag in <c>emerge</c>, see <c>man emerge</c>.
138</p>
139
140</body>
141</section>
142<section>
128<title>Configuring the kernel</title> 143<title>Configuring The Kernel</title>
129<body> 144<body>
130 145
131<p> 146<p>
132ACPI (Advanced Configuration and Power Interface) support in the kernel is 147ACPI (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 148still work in progress. Using a recent kernel will make sure you'll get the
134most out of it. 149most out of it.
135</p> 150</p>
136 151
137<p> 152<p>
138In kernel config, activate at least these options: 153There are different kernel sources in Portage. I'd recommend using
154<c>gentoo-sources</c> or <c>suspend2-sources</c>. The latter contains patches
155for Software Suspend 2, see the chapter about <uri link="#doc_chap7">sleep
156states</uri> for more details. When configuring the kernel, activate at least
157these options:
139</p> 158</p>
140 159
141<pre caption="Minimum kernel setup for Power Management (Kernel 2.6)"> 160<pre caption="Minimum kernel setup for Power Management (Kernel 2.6)">
142Power Management Options ---&gt; 161Power Management Options ---&gt;
143 [*] Power Management Support 162 [*] Power Management Support
144 [ ] Software Suspend 163 [ ] Software Suspend
145 [ ] Suspend-to-Disk Support
146 164
147 ACPI( Advanced Configuration and Power Interface ) Support ---&gt; 165 ACPI( Advanced Configuration and Power Interface ) Support ---&gt;
148 [*] ACPI Support 166 [*] ACPI Support
149 [ ] Sleep States 167 [ ] Sleep States
168 [ ] /proc/acpi/sleep (deprecated)
150 [*] AC Adapter 169 [*] AC Adapter
151 [*] Battery 170 [*] Battery
152 &lt;M&gt; Button 171 &lt;M&gt; Button
172 &lt;M&gt; Video
173 [ ] Generic Hotkey
153 &lt;M&gt; Fan 174 &lt;M&gt; Fan
154 &lt;M&gt; Processor 175 &lt;M&gt; Processor
155 &lt;M&gt; Thermal Zone 176 &lt;M&gt; Thermal Zone
156 &lt; &gt; ASUS/Medion Laptop Extras 177 &lt; &gt; ASUS/Medion Laptop Extras
178 &lt; &gt; IBM ThinkPad Laptop Extras
157 &lt; &gt; Toshiba Laptop Extras 179 &lt; &gt; Toshiba Laptop Extras
180 (0) Disable ACPI for systems before Jan 1st this year
158 [ ] Debug Statements 181 [ ] Debug Statements
159 182 [*] Power Management Timer Support
183 &lt; &gt; ACPI0004,PNP0A05 and PNP0A06 Container Driver (EXPERIMENTAL)
184
160 CPU Frequency Scaling ---&gt; 185 CPU Frequency Scaling ---&gt;
161 [*] CPU Frequency scaling 186 [*] CPU Frequency scaling
187 [ ] Enable CPUfreq debugging
188 &lt; &gt; CPU frequency translation statistics
189 [ ] CPU frequency translation statistics details
162 Default CPUFreq governor (userspace) 190 Default CPUFreq governor (userspace)
163 &lt;*&gt; 'performance' governor 191 &lt;*&gt; 'performance' governor
164 &lt;*&gt; 'powersave' governor 192 &lt;*&gt; 'powersave' governor
165 &lt;*&gt; 'ondemand' cpufreq policy governor 193 &lt;*&gt; 'ondemand' cpufreq policy governor
194 &lt;*&gt; 'conservative' cpufreq governor
166 &lt;*&gt; CPU frequency table helpers 195 &lt;*&gt; CPU frequency table helpers
167 &lt;M&gt; ACPI Processor P-States driver 196 &lt;M&gt; ACPI Processor P-States driver
168 &lt;*&gt; <i>CPUFreq driver for your processor</i> 197 &lt;*&gt; <i>CPUFreq driver for your processor</i>
169</pre> 198</pre>
170 199
171<p> 200<p>
172Decide yourself whether you want to enable Software Suspend, Suspend-to-Disk and 201Decide yourself whether you want to enable Software Suspend, and Sleep States
173Sleep States (see below). If you own an ASUS, Medion or Toshiba laptop, enable 202(see below). If you own an ASUS, Medion, IBM Thinkpad or Toshiba laptop, enable
174the appropriate section. 203the appropriate section.
175</p> 204</p>
176 205
177<p> 206<p>
178The 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.
179each 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
180driver 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
181modulation</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.
182Consult the kernel documentation if you're unsure which one to take. 211Consult the kernel documentation if you're unsure which one to take.
183</p> 212</p>
184 213
185<p> 214<p>
186Compile 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
187into 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
188the 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
189battery 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
190compile them into the kernel and start acpid by executing 219compile them into the kernel and start acpid by executing <c>/etc/init.d/acpid
191<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
192it on startup. You'll soon see how to use it. 221soon see how to use it.
193</p> 222</p>
194 223
195<pre caption="Installing acpid"> 224<pre caption="Installing acpid">
196# <i>emerge sys-power/acpid</i> 225# <i>emerge sys-power/acpid</i>
197# <i>/etc/init.d/acpid start</i> 226# <i>/etc/init.d/acpid start</i>
199</pre> 228</pre>
200 229
201</body> 230</body>
202</section> 231</section>
203<section> 232<section>
204<title>Creating a "battery" runlevel</title> 233<title>Creating A "battery" Runlevel</title>
205<body> 234<body>
206 235
207<p> 236<p>
208The default policy will be to enable Power Management only when needed - 237The default policy will be to enable Power Management only when needed -
209running on batteries. To make the switch between AC and battery convenient, 238running on batteries. To make the switch between AC and battery convenient,
210create 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
211stopping Power Management. 240stopping Power Management.
212</p> 241</p>
213 242
214<note> 243<note>
215You 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
216runlevel. 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
217up. The next sections assume a runlevel <e>battery</e> exists. 246up. The next sections assume a runlevel <c>battery</c> exists.
218</note> 247</note>
219 248
220<pre caption="Creating a battery runlevel"> 249<pre caption="Creating a battery runlevel">
221# <i>cd /etc/runlevels</i> 250# <i>cd /etc/runlevels</i>
222# <i>cp -a default battery</i> 251# <i>cp -a default battery</i>
223</pre> 252</pre>
224 253
225<p> 254<p>
226Finished. Your new runlevel <e>battery</e> contains everything like 255Finished. Your new runlevel <c>battery</c> contains everything like
227<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
228change it. 257change it.
229</p> 258</p>
230 259
231</body> 260</body>
232</section> 261</section>
233<section> 262<section>
234<title>Reacting on ACPI events</title> 263<title>Reacting On ACPI Events</title>
235<body> 264<body>
236 265
237<p> 266<p>
238Typical 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
239the 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
240cause a runlevel switch. Create the following files to switch between 269cause a runlevel switch. A small script will take care of it.
241<e>default</e> and <e>battery</e> runlevel depending on the power source: 270</p>
271
272<p>
273First you need a script which changes the runlevel to <c>default</c>
274respectively <c>battery</c> depending on the power source. The script uses the
275<c>on_ac_power</c> command from <c>sys-power/powermgmt-base</c> - make sure the
276package is installed on your system.
277</p>
278
279<pre caption="Installing powermgt-base">
280# <i>emerge powermgmt-base</i>
281</pre>
282
283<p>
284You are now able to determine the power source by executing <c>on_ac_power
285&amp;&amp; echo AC available || echo Running on batteries</c> in a shell. The
286script below is responsible for changing runlevels. Save it as
287<path>/etc/acpi/actions/pmg_switch_runlevel.sh</path>.
242</p> 288</p>
243 289
244<pre caption="/etc/acpi/actions/pmg_switch_runlevel.sh"> 290<pre caption="/etc/acpi/actions/pmg_switch_runlevel.sh">
245#!/bin/bash 291#!/bin/bash
246 292
250<comment># END configuration</comment> 296<comment># END configuration</comment>
251 297
252 298
253if [ ! -d "/etc/runlevels/${RUNLEVEL_AC}" ] 299if [ ! -d "/etc/runlevels/${RUNLEVEL_AC}" ]
254then 300then
255 logger "${0}: Runlevel ${RUNLEVEL_AC} does not exist. Aborting." 301 logger "${0}: Runlevel ${RUNLEVEL_AC} does not exist. Aborting."
256 exit 1 302 exit 1
257fi 303fi
258 304
259if [ ! -d "/etc/runlevels/${RUNLEVEL_BATTERY}" ] 305if [ ! -d "/etc/runlevels/${RUNLEVEL_BATTERY}" ]
260then 306then
261 logger "${0}: Runlevel ${RUNLEVEL_BATTERY} does not exist. Aborting." 307 logger "${0}: Runlevel ${RUNLEVEL_BATTERY} does not exist. Aborting."
262 exit 1 308 exit 1
263fi 309fi
264 310
265if on_ac_power 311if on_ac_power
266then 312then
267 if [[ "$(cat /var/lib/init.d/softlevel)" != "${RUNLEVEL_AC}" ]] 313 if [[ "$(&lt;/var/lib/init.d/softlevel)" != "${RUNLEVEL_AC}" ]]
268 then 314 then
269 logger "Switching to ${RUNLEVEL_AC} runlevel" 315 logger "Switching to ${RUNLEVEL_AC} runlevel"
270 /sbin/rc ${RUNLEVEL_AC} 316 /sbin/rc ${RUNLEVEL_AC}
271 fi 317 fi
272elif [[ "$(cat /var/lib/init.d/softlevel)" != "${RUNLEVEL_BATTERY}" ]] 318elif [[ "$(&lt;/var/lib/init.d/softlevel)" != "${RUNLEVEL_BATTERY}" ]]
273then 319then
274 logger "Switching to ${RUNLEVEL_BATTERY} runlevel" 320 logger "Switching to ${RUNLEVEL_BATTERY} runlevel"
275 /sbin/rc ${RUNLEVEL_BATTERY} 321 /sbin/rc ${RUNLEVEL_BATTERY}
276fi 322fi
277</pre> 323</pre>
324
325<p>
326Dont forget to run <c>chmod +x /etc/acpi/actions/pmg_switch_runlevel.sh</c> to
327make the script executable. The last thing that needs to be done is calling the
328script whenever the power source changes. That's done by catching ACPI events
329with the help of <c>acpid</c>. First you need to know which events are
330generated when the power source changes. The events are called
331<c>ac_adapter</c> and <c>battery</c> on most laptops, but it might be different
332on yours.
333</p>
334
335<pre caption="Determining ACPI events for changing the power source">
336# <i>tail -f /var/log/acpid | grep "received event"</i>
337</pre>
338
339<p>
340Run the command above and pull the power cable. You should see something like
341this:
342</p>
343
344<pre caption="Sample output for power source changes">
345[Tue Sep 20 17:39:06 2005] received event "ac_adapter AC 00000080 00000000"
346[Tue Sep 20 17:39:06 2005] received event "battery BAT0 00000080 00000001"
347</pre>
348
349<p>
350The interesting part is the quoted string after <c>received event</c>. It will
351be matched by the event line in the files you are going to create below. Don't
352worry if your system generates multiple events or always the same. As long as
353any event is generated, runlevel changing will work.
354</p>
278 355
279<pre caption="/etc/acpi/events/pmg_ac_adapter"> 356<pre caption="/etc/acpi/events/pmg_ac_adapter">
280<comment># replace "ac_adapter" below with the event generated on your laptop</comment> 357<comment># replace "ac_adapter" below with the event generated on your laptop</comment>
281<comment># See /var/log/acpid</comment> 358<comment># For example, ac_adapter.* will match ac_adapter AC 00000080 00000000</comment>
282event=ac_adapter.* 359event=ac_adapter.*
283action=/etc/acpi/actions/pmg_switch_runlevel.sh %e 360action=/etc/acpi/actions/pmg_switch_runlevel.sh %e
284</pre> 361</pre>
285 362
286<pre caption="/etc/acpi/events/pmg_battery"> 363<pre caption="/etc/acpi/events/pmg_battery">
287<comment># replace "battery" below with the event generated on your laptop</comment> 364<comment># replace "battery" below with the event generated on your laptop</comment>
288<comment># See /var/log/acpid</comment> 365<comment># For example, battery.* will match battery BAT0 00000080 00000001</comment>
289event=battery.* 366event=battery.*
290action=/etc/acpi/actions/pmg_switch_runlevel.sh %e 367action=/etc/acpi/actions/pmg_switch_runlevel.sh %e
291</pre> 368</pre>
292 369
293<p> 370<p>
294Additionally you need the package sys-power/powermgmt-base which contains 371Finally acpid has to be restarted to recognize the changes.
295the <c>on_ac_power</c> utility. The file <path>pmg_switch_runlevel.sh</path>
296must be executable.
297</p> 372</p>
298 373
299<pre caption="Finishing runlevel switching with acpid"> 374<pre caption="Finishing runlevel switching with acpid">
300<i># emerge powermgmt-base</i>
301<i># chmod +x /etc/acpi/actions/pmg_switch_runlevel.sh</i>
302<i># /etc/init.d/acpid restart</i> 375# <i>/etc/init.d/acpid restart</i>
303</pre> 376</pre>
304 377
305<p> 378<p>
306Give 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
307mode" or "Switching to battery mode" messages. See the Troubleshooting 380mode" or "Switching to battery mode" messages. See the <uri
308section 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.
309</p> 383</p>
310 384
311<p> 385<p>
312Due 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
313<e>default</e> regardless of the AC/battery state. You can add another entry 387<c>default</c> regardless of the AC/battery state. This is fine when running
314to the boot loader with <c>softlevel=battery</c>, but it's likely to forget 388from AC, but we'd like to boot into the battery runlevel otherwise. One
315choosing it. A better way is faking an ACPI event in the end of the boot 389solution would be to add another entry to the boot loader with the parameter
316process and let the <path>/etc/acpi/default.sh</path> script decide whether a 390<c>softlevel=battery</c>, but it's likely to forget choosing it. A better way
391is faking an ACPI event in the end of the boot process and letting
392<path>pmg_switch_runlevel.sh</path> script decide whether a runlevel change is
317runlevel 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
318favourite editor and add these lines: 394and add these lines:
319</p> 395</p>
320 396
321<pre caption="Runlevel switch at boot time by editing local.start"> 397<pre caption="Runlevel adjustment at boot time by editing local.start">
322<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>
323/etc/acpi/actions/pmg_switch_runlevel.sh "battery/battery" 399/etc/acpi/actions/pmg_switch_runlevel.sh "battery/battery"
324</pre> 400</pre>
325 401
326<p> 402<p>
327Prepared like this you can activate Power Management policies for individual 403Prepared like this you can activate Power Management policies for individual
328devices. 404devices.
329</p> 405</p>
330 406
331</body> 407</body>
332</section> 408</section>
333</chapter> 409</chapter>
334 410
335<chapter> 411<chapter>
336<title>CPU Power Management</title> 412<title>CPU Power Management</title>
337<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>
338<title>Some technical terms</title> 426<title>Some Technical Terms</title>
339<body> 427<body>
340 428
341<p> 429<p>
342CPU 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
343you. Here's a quick introduction. 431you. Here's a quick introduction.
344</p> 432</p>
345 433
346<p> 434<p>
347First of all, the kernel has to be able to change the processor's frequency. The 435First of all, the kernel has to be able to change the processor's frequency.
348<e>CPUfreq processor driver</e> knows the commands to do it on your CPU. Thus 436The <b>CPUfreq processor driver</b> knows the commands to do it on your CPU.
349it's important to choose the right one in your kernel. You should already have 437Thus it's important to choose the right one in your kernel. You should already
350done it above. Once the kernel knows how to change frequencies, it has to know 438have done it above. Once the kernel knows how to change frequencies, it has to
351which frequency it should set. This is done according to the <e>policy</e> which 439know which frequency it should set. This is done according to the <b>policy</b>
352consists of a <e>CPUfreq policy</e> and a <e>governor</e>. A CPUfreq policy are 440which consists of a <b>CPUfreq policy</b> and a <b>governor</b>. A CPUfreq
353just two numbers which define a range the frequency has to stay between - 441policy are just two numbers which define a range the frequency has to stay
354minimal and maximal frequency. The governor now decides which of the available 442between - minimal and maximal frequency. The governor now decides which of the
355frequencies in between minimal and maximal frequency to choose. For example, the 443available frequencies in between minimal and maximal frequency to choose. For
356<e>powersave governor</e> always chooses the lowest frequency available, the 444example, the <b>powersave governor</b> always chooses the lowest frequency
357<e>performance governor</e> the highest one. The <e>userspace governor</e> makes 445available, the <b>performance governor</b> the highest one. The <b>userspace
358no decision but chooses whatever the user (or a program in userspace) wants - 446governor</b> makes no decision but chooses whatever the user (or a program in
359which means it reads the frequency from 447userspace) wants - which means it reads the frequency from
360<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed</path>. 448<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed</path>.
361</p> 449</p>
362 450
363<p> 451<p>
364This 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.
365Dynamics however can be accomplished with various approaches. For example, 453Dynamics however can be accomplished with various approaches. For example, the
366the <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.
367load. 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>,
368<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
369enable or disable dynamic frequency changes depending on power source. 457dynamic frequency changes depending on power source.
370</p> 458</p>
371 459
372</body> 460</body>
373</section>
374<section> 461</section>
462<section>
375<title>Setting the frequency manually</title> 463<title>Setting The Frequency Manually</title>
376<body> 464<body>
377 465
378<p> 466<p>
379Decreasing 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
380energy 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
383between performance loss and energy saving. 471between performance loss and energy saving.
384</p> 472</p>
385 473
386<note> 474<note>
387Not 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
388of supported processors in the <e>Troubleshooting</e> section to verify your's 476of supported processors in the <uri link="#doc_chap8">Troubleshooting</uri>
389is supported. 477section to verify yours is supported.
390</note> 478</note>
391 479
392<p> 480<p>
393It'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
394tool 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>
402<p> 490<p>
403Here is an example output: 491Here is an example output:
404</p> 492</p>
405 493
406<pre caption="Sample output from cpufreq-info"> 494<pre caption="Sample output from cpufreq-info">
407cpufrequtils 0.2: cpufreq-info (C) Dominik Brodowski 2004 495cpufrequtils 0.3: cpufreq-info (C) Dominik Brodowski 2004
408Report errors and bugs to linux@brodo.de, please. 496Report errors and bugs to linux@brodo.de, please.
409analyzing CPU 0: 497analyzing CPU 0:
410 driver: centrino 498 driver: centrino
411 CPUs which need to switch frequency at the same time: 0 499 CPUs which need to switch frequency at the same time: 0
412 hardware limits: 600 MHz - 1.40 GHz 500 hardware limits: 600 MHz - 1.40 GHz
413 available frequency steps: 600 MHz, 800 MHz, 1000 MHz, 1.20 GHz, 1.40 GHz 501 available frequency steps: 600 MHz, 800 MHz, 1000 MHz, 1.20 GHz, 1.40 GHz
414 available cpufreq governors: ondemand, powersave, userspace, performance 502 available cpufreq governors: conservative, ondemand, powersave, userspace, performance
415 current policy: frequency should be within 924 MHz and 1.40 GHz. 503 current policy: frequency should be within 924 MHz and 1.40 GHz.
416 The governor "performance" may decide which speed to use 504 The governor "performance" may decide which speed to use
417 within this range. 505 within this range.
418 current CPU frequency is 1.40 GHz (asserted by call to hardware). 506 current CPU frequency is 1.40 GHz.
419</pre> 507</pre>
420 508
421<p> 509<p>
422Now 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.
423Run <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
424governor 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
425expected, 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
426guide. 514section</uri> in the end of this guide.
427</p> 515</p>
428 516
429</body> 517</body>
430</section> 518</section>
431<section> 519<section>
432<title>Automated frequency adaption</title> 520<title>Automated frequency adaption</title>
433<body> 521<body>
434 522
435<p> 523<p>
436The 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
437set the appropriate frequency automatically. There are many different approaches 525set the appropriate frequency automatically. There are many different
438to do this. The following table gives a quick overview to help you decide on one 526approaches to do this. The following table gives a quick overview to help you
439of them. It's roughly seperated in three categories <e>kernel</e> for approaches 527decide on one of them. It's roughly separated in three categories <b>kernel</b>
440that only need kernel support, <e>daemon</e> for programs that run in the 528for approaches that only need kernel support, <b>daemon</b> for programs that
441background and <e>graphical</e> for programs that provide a GUI for easy 529run in the background and <b>graphical</b> for programs that provide a GUI for
442configuration and changes. 530easy configuration and changes.
443</p> 531</p>
444 532
445<table> 533<table>
446<tr> 534<tr>
447 <th>Name</th> 535 <th>Name</th>
456 <ti>Kernel</ti> 544 <ti>Kernel</ti>
457 <ti>CPU load</ti> 545 <ti>CPU load</ti>
458 <ti>N.A.</ti> 546 <ti>N.A.</ti>
459 <ti>N.A.</ti> 547 <ti>N.A.</ti>
460 <ti> 548 <ti>
549 Chooses maximal frequency on CPU load and slowly steps down when the CPU is
550 idle. Further tuning through files in
551 <path>/sys/devices/system/cpu/cpu0/cpufreq/ondemand/</path>. Still requires
552 userland tools (programs, scripts) if governor switching or similar is
553 desired.
554 </ti>
555</tr>
556<tr>
557 <ti>'conservative' governor</ti>
558 <ti>Kernel</ti>
559 <ti>CPU load</ti>
560 <ti>N.A.</ti>
561 <ti>N.A.</ti>
562 <ti>
563 Unlike the ondemand governor, conversative doesn't jump to maximum
564 frequency when CPU load is high, but increases the frequency step by step.
461 Further tuning through files in 565 Further tuning through files in
462 <path>/sys/devices/system/cpu/cpu0/cpufreq/ondemand/</path>. Still requires 566 <path>/sys/devices/system/cpu/cpu0/cpufreq/ondemand/</path>. Still requires
463 userland tools (programs, scripts) if governor switching or similar is 567 userland tools (programs, scripts) if governor switching or similar is
464 desired. 568 desired.
465 </ti> 569 </ti>
476 </ti> 580 </ti>
477</tr> 581</tr>
478<tr> 582<tr>
479 <ti><uri link="http://sourceforge.net/projects/cpufreqd/">cpufreqd</uri></ti> 583 <ti><uri link="http://sourceforge.net/projects/cpufreqd/">cpufreqd</uri></ti>
480 <ti>Daemon</ti> 584 <ti>Daemon</ti>
481 <ti>Battery state, CPU load, running programs</ti> 585 <ti>Battery state, CPU load, temperature, running programs and more</ti>
482 <ti>All available</ti> 586 <ti>All available</ti>
483 <ti>None</ti> 587 <ti>None</ti>
484 <ti> 588 <ti>
485 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.
486 </ti> 593 </ti>
487</tr> 594</tr>
488<tr> 595<tr>
489 <ti> 596 <ti>
490 <uri link="http://www.deater.net/john/powernowd.html">powernowd</uri> 597 <uri link="http://www.deater.net/john/powernowd.html">powernowd</uri>
496 <ti> 603 <ti>
497 Supports SMP. 604 Supports SMP.
498 </ti> 605 </ti>
499</tr> 606</tr>
500<tr> 607<tr>
608 <ti>
609 <uri
610 link="http://fatcat.ftj.agh.edu.pl/~nelchael/index.php?cat=projs&amp;subcat=ncpufreqd&amp;language=en">ncpufreqd</uri>
611 </ti>
612 <ti>Daemon</ti>
613 <ti>Temperature</ti>
614 <ti>None</ti>
615 <ti>Powersave, performance</ti>
616 <ti>
617 Toggles the used governor between performance and powersave depending on
618 system temperature. Very useful on laptops with notorious heat problems.
619 </ti>
620</tr>
621<tr>
501 <ti><uri link="http://www.goop.org/~jeremy/speedfreq/">speedfreq</uri></ti> 622 <ti><uri link="http://www.goop.org/~jeremy/speedfreq/">speedfreq</uri></ti>
502 <ti>Daemon</ti> 623 <ti>Daemon</ti>
503 <ti>CPU load</ti> 624 <ti>CPU load</ti>
504 <ti>None</ti> 625 <ti>None</ti>
505 <ti>Dynamic, powersave, performance, fixed speed</ti> 626 <ti>Dynamic, powersave, performance, fixed speed</ti>
506 <ti> 627 <ti>
507 Small yet powerful with an useful client/server interface. Requires a 2.6 628 Easy to configure with a nice client/server interface. Requires a 2.6
508 kernel. Doesn't seem to be maintained anymore and will be removed from 629 kernel. Unmaintained, broken and thus removed from Portage. Please switch
509 Portage in the near future. 630 to cpufreqd if you're still using it.
510 </ti> 631 </ti>
511</tr> 632</tr>
512<tr> 633<tr>
513 <ti><uri link="http://cpuspeedy.sourceforge.net/">gtk-cpuspeedy</uri></ti> 634 <ti><uri link="http://cpuspeedy.sourceforge.net/">gtk-cpuspeedy</uri></ti>
514 <ti>Graphical</ti> 635 <ti>Graphical</ti>
531 </ti> 652 </ti>
532</tr> 653</tr>
533</table> 654</table>
534 655
535<p> 656<p>
536While adjusting the frequency to the current load looks simple on the first 657While adjusting the frequency to the current load looks simple at a first
537view, it's not such a trivial task. A bad algorithm can cause switching between 658glance, it's not such a trivial task. A bad algorithm can cause switching
538two frequencies all the time or wasting energy when setting frequency to an 659between two frequencies all the time or wasting energy when setting frequency
539unnecessary high level. 660to an unnecessary high level.
540</p> 661</p>
541 662
542<p> 663<p>
543Which 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>:
544</p> 665</p>
549 670
550<p> 671<p>
551<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>.
552The 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
553replacing it with the one from Gentoo developer Henrik Brix Andersen (see 674replacing it with the one from Gentoo developer Henrik Brix Andersen (see
554below). 675below). Please notice that you need cpufreqd-2.0.0 or later. Earlier versions
676have a different syntax for the config file.
555</p> 677</p>
556 678
557<pre caption="/etc/cpufreqd.conf"> 679<pre caption="/etc/cpufreqd.conf (cpufreqd-2.0.0 and later)">
558[General] 680[General]
559pidfile=/var/run/cpufreqd.pid 681pidfile=/var/run/cpufreqd.pid
560poll_interval=2 682poll_interval=3
561pm_type=acpi 683enable_plugins=acpi_ac, acpi_battery
684enable_remote=1
685remote_group=wheel
562verbosity=5 686verbosity=5
687[/General]
563 688
564[Profile] 689[Profile]
565name=ondemand 690name=ondemand
566minfreq=0% 691minfreq=0%
567maxfreq=100% 692maxfreq=100%
568policy=ondemand 693policy=ondemand
694[/Profile]
695
696[Profile]
697name=conservative
698minfreq=0%
699maxfreq=100%
700policy=conservative
701[/Profile]
569 702
570[Profile] 703[Profile]
571name=powersave 704name=powersave
572minfreq=0% 705minfreq=0%
573maxfreq=100% 706maxfreq=100%
574policy=powersave 707policy=powersave
708[/Profile]
575 709
576[Profile] 710[Profile]
577name=performance 711name=performance
578minfreq=0% 712minfreq=0%
579maxfreq=100% 713maxfreq=100%
580policy=performance 714policy=performance
715[/Profile]
581 716
582[Rule] 717[Rule]
583name=battery 718name=battery
584ac=off 719ac=off
585profile=ondemand 720profile=conservative
721[/Rule]
586 722
587[Rule] 723[Rule]
588name=battery_low 724name=battery_low
589ac=off 725ac=off
590battery_interval=0-10 726battery_interval=0-10
591profile=powersave 727profile=powersave
728[/Rule]
592 729
593[Rule] 730[Rule]
594name=ac 731name=ac
595ac=on 732ac=on
596profile=performance 733profile=ondemand
734[/Rule]
597</pre> 735</pre>
598 736
599<p>
600You can't use a percentage value like above for min_freq and max_freq if you
601are using kernel 2.6 with the sysfs interface (you probably do). Replace it
602with the lowest and highest frequency as reported by <c>cpufreq-info
603--hwlimits</c>. For example, on my 1.4 GHz Pentium M I put in
604</p> 737<p>
605 738Now you can start the cpufreqd daemon. Add it to the <c>default</c> and
606<pre caption="Sample values for minfreq and maxfreq"> 739<c>battery</c> runlevel as well.
607minfreq=600000
608maxfreq=1400000
609</pre>
610
611<p>
612Last not least start the daemon.
613</p> 740</p>
614 741
615<pre caption="Starting cpufreqd"> 742<pre caption="Starting cpufreqd">
616# <i>rc-update add cpufreqd default battery</i> 743# <i>rc-update add cpufreqd default battery</i>
617# <i>rc</i> 744# <i>rc</i>
618</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>
619 755
620<warn> 756<warn>
621Do 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
622confusion like switching between two frequencies all the time. 758confusion like switching between two frequencies all the time.
623</warn> 759</warn>
624 760
625</body> 761</body>
626</section> 762</section>
627
628<section> 763<section>
629<title>Verifying the result</title> 764<title>Verifying the result</title>
630
631<body> 765<body>
632 766
633<p> 767<p>
634The 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
635do so is monitoring CPU speed while working with your laptop: 769do so is monitoring CPU speed while working with your laptop:
638<pre caption="Monitoring CPU speed"> 772<pre caption="Monitoring CPU speed">
639# <i>watch grep \"cpu MHz\" /proc/cpuinfo</i> 773# <i>watch grep \"cpu MHz\" /proc/cpuinfo</i>
640</pre> 774</pre>
641 775
642<p> 776<p>
643If <path>/proc/cpuinfo</path> doesn't get updated (see Troubleshooting), 777If <path>/proc/cpuinfo</path> doesn't get updated (see <uri
644monitor the CPU frequency with: 778link="#doc_chap8">Troubleshooting</uri>), monitor the CPU frequency with:
645</p> 779</p>
646 780
647<pre caption="Alternative CPU speed monitoring"> 781<pre caption="Alternative CPU speed monitoring">
648# <i>watch x86info -mhz</i> 782# <i>watch x86info -mhz</i>
649</pre> 783</pre>
650 784
651<p> 785<p>
652Depending on your setup, CPU speed should increase on heavy load, decrease on 786Depending on your setup, CPU speed should increase on heavy load, decrease on
653no activity or just stay at the same level. When using cpufreqd and verbosity 787no activity or just stay at the same level. When using <c>cpufreqd</c> and
654set to 5 or higher in <path>cpufreqd.conf</path> you'll get additional 788verbosity set to 5 or higher in <path>cpufreqd.conf</path> you'll get
655information about what's happening reported to syslog. 789additional information about what's happening reported to <c>syslog</c>.
656</p> 790</p>
657 791
658</body> 792</body>
659</section> 793</section>
660</chapter> 794</chapter>
661 795
662<chapter> 796<chapter>
663<title>LCD Power Management</title> 797<title>LCD Power Management</title>
664<section> 798<section>
665<title>Energy consumer no. 1</title>
666<body> 799<body>
667 800
668<p> 801<p>
669As you can see in <uri link="#doc_chap1_fig1">figure 1.1</uri>, the LCD display 802As you can see in <uri link="#doc_chap1_fig1">figure 1.1</uri>, the LCD
670consumes the biggest part of energy (might not be the case for non-mobile 803display consumes the biggest part of energy (might not be the case for
671CPU's). Thus it's quite important not only to shut the display off when not 804non-mobile CPU's). Thus it's quite important not only to shut the display off
672needed, but also to reduce it's backlight if possible. Most laptops offer the 805when not needed, but also to reduce it's backlight if possible. Most laptops
673possibility to control the backlight dimming. 806offer the possibility to control the backlight dimming.
674</p>
675
676<p> 807</p>
808
809</body>
810</section>
811<section>
812<title>Standby settings</title>
813<body>
814
815<p>
677First thing to check is the standby/suspend/off timings of the display. As this 816The first thing to check is the standby/suspend/off timings of the display. As
678depends heavily on your windowmanager, I'll let you figure it out yourself. 817this depends heavily on your windowmanager, I'll let you figure it out
679Just two common places: Blanking the terminal can be done with <c>setterm 818yourself. Just two common places: Blanking the terminal can be done with
680-blank &lt;number-of-minutesM&gt;</c>, <c>setterm -powersave on</c> and 819<c>setterm -blank &lt;number-of-minutesM&gt;</c>, <c>setterm -powersave on</c>
681<c>setterm -powerdown &lt;number-of-minutesM&gt;</c>. 820and <c>setterm -powerdown &lt;number-of-minutesM&gt;</c>. For X.org, modify
682For Xorg, modify <path>/etc/X11/xorg.conf</path> similar to this: 821<path>/etc/X11/xorg.conf</path> similar to this:
683</p> 822</p>
684 823
685<pre caption="LCD suspend settings in Xorg and XFree86"> 824<pre caption="LCD suspend settings in X.org and XFree86">
686Section "ServerLayout" 825Section "ServerLayout"
687 Identifier [...] 826 Identifier [...]
688 [...] 827 [...]
689 Option "BlankTime" "5" <comment># Blank the screen after 5 minutes (Fake)</comment> 828 Option "BlankTime" "5" <comment># Blank the screen after 5 minutes (Fake)</comment>
690 Option "StandbyTime" "10" <comment># Turn off screen after 10 minutes (DPMS)</comment> 829 Option "StandbyTime" "10" <comment># Turn off screen after 10 minutes (DPMS)</comment>
704 843
705<p> 844<p>
706This is the same for XFree86 and <path>/etc/X11/XF86Config</path>. 845This is the same for XFree86 and <path>/etc/X11/XF86Config</path>.
707</p> 846</p>
708 847
848</body>
849</section>
850<section>
851<title>Backlight dimming</title>
852<body>
853
709<p> 854<p>
710Probably more important is the backlight dimming. If you have access to the 855Probably more important is the backlight dimming. If you have access to the
711dimming settings via a tool, write a small script that dims the backlight in 856dimming settings via a tool, write a small script that dims the backlight in
712battery mode and place it in your <e>battery</e> runlevel. The following script 857battery mode and place it in your <c>battery</c> runlevel. The following script
713should work on most IBM Thinkpads. It needs the <c>app-laptop/ibm-acpi</c> 858should work on most IBM Thinkpads and Toshiba laptops. You've got to enable the
714package or the appropriate option in your kernel has to be enabled. 859appropriate option in your kernel (IBM Thinkpads only). For Toshiba laptops,
860install <c>app-laptop/acpitool</c> and skip configuration of <c>ibm_acpi</c> as
861described below.
715</p> 862</p>
716 863
717<warn> 864<warn>
718Support for setting brightness is marked experimental in ibm-acpi. It accesses 865Support for setting brightness is marked experimental in ibm-acpi. It accesses
719hardware directly and may cause severe harm to your system. Please read the 866hardware directly and may cause severe harm to your system. Please read the
725with the experimental parameter. 872with the experimental parameter.
726</p> 873</p>
727 874
728<pre caption="automatically loading the ibm_acpi module"> 875<pre caption="automatically loading the ibm_acpi module">
729<comment>(Please read the warnings above before doing this!)</comment> 876<comment>(Please read the warnings above before doing this!)</comment>
730<i># emerge ibm-acpi</i>
731<i># echo "options ibm_acpi experimental=1" >> /etc/modules.d/ibm_acpi</i> 877# <i>echo "options ibm_acpi experimental=1" >> /etc/modules.d/ibm_acpi</i>
732<i># /sbin/modules-update</i> 878# <i>/sbin/modules-update</i>
733<i># echo ibm_acpi >> /etc/modules.autoload.d/kernel-2.6</i> 879# <i>echo ibm_acpi >> /etc/modules.autoload.d/kernel-2.6</i>
734<i># modprobe ibm_acpi</i> 880# <i>modprobe ibm_acpi</i>
735</pre> 881</pre>
736 882
737<p> 883<p>
738This should work without error messages and a file 884This should work without error messages and a file
739<path>/proc/acpi/ibm/brightness</path> should be created after loading the 885<path>/proc/acpi/ibm/brightness</path> should be created after loading the
740module. An init script will take care of choosing the brightness according 886module. An init script will take care of choosing the brightness according to
741to the power source. 887the power source.
742</p> 888</p>
743 889
744<pre caption="/etc/conf.d/lcd-brightness"> 890<pre caption="/etc/conf.d/lcd-brightness">
745<comment># See /proc/acpi/ibm/brightness for available values</comment> 891<comment># See /proc/acpi/ibm/brightness for available values</comment>
746<comment># Please read /usr/share/doc/ibm-acpi-*/README.gz</comment> 892<comment># Please read /usr/src/linux/Documentation/ibm-acpi.txt</comment>
747 893
748<comment># brigthness level in ac mode. Default is 7.</comment> 894<comment># brigthness level in ac mode. Default is 7.</comment>
749BRIGHTNESS_AC=7 895BRIGHTNESS_AC=7
750 896
751<comment># brightness level in battery mode. Default is 4.</comment> 897<comment># brightness level in battery mode. Default is 4.</comment>
766 if [ -f /proc/acpi/ibm/brightness ] 912 if [ -f /proc/acpi/ibm/brightness ]
767 then 913 then
768 ebegin "Setting LCD brightness" 914 ebegin "Setting LCD brightness"
769 echo "level ${LEVEL}" > /proc/acpi/ibm/brightness 915 echo "level ${LEVEL}" > /proc/acpi/ibm/brightness
770 eend $? 916 eend $?
917 elif [[ -e /usr/bin/acpitool &amp;&amp; -n $(acpitool -T | grep "LCD brightness") ]]
918 then
919 ebegin "Setting LCD brightness"
920 acpitool -l $LEVEL >/dev/null || ewarn "Unable to set lcd brightness"
921 eend $?
771 else 922 else
772 ewarn "Setting LCD brightness is not supported." 923 ewarn "Setting LCD brightness is not supported."
773 ewarn "Check that ibm_acpi is loaded into the kernel" 924 ewarn "For IBM Thinkpads, check that ibm_acpi is loaded into the kernel"
925 ewarn "For Toshiba laptops, you've got to install app-laptop/acpitool"
774 fi 926 fi
775} 927}
776 928
777start() { 929start() {
778 set_brightness 930 set_brightness
787When done, make sure brightness is adjusted automatically by adding it to the 939When done, make sure brightness is adjusted automatically by adding it to the
788battery runlevel. 940battery runlevel.
789</p> 941</p>
790 942
791<pre caption="Enabling automatic brightness adjustment"> 943<pre caption="Enabling automatic brightness adjustment">
792<i># chmod +x /etc/init.d/lcd-brightness</i> 944# <i>chmod +x /etc/init.d/lcd-brightness</i>
793<i># rc-update add lcd-brightness battery</i> 945# <i>rc-update add lcd-brightness battery</i>
794<i># rc</i> 946# <i>rc</i>
795</pre> 947</pre>
796 948
797</body> 949</body>
798</section> 950</section>
799</chapter> 951</chapter>
800 952
801<chapter> 953<chapter>
802<title>Disk Power Management</title> 954<title>Disk Power Management</title>
803<section> 955<section>
804<title>Sleep when idle</title> 956<body>
957
958<p>
959Hard disks consume less energy in sleep mode. Therefore it makes sense to
960activate power saving features whenever the hard disk is not used for a certain
961amount of time. I'll show you two alternative possibilities to do it. First,
962laptop-mode will save most energy due to several measures which prevent or at
963least delay write accesses. The drawback is that due to the delayed write
964accesses a power outage or kernel crash will be more dangerous for data loss.
965If you don't like this, you have to make sure that there are no processes which
966write to your hard disk frequently. Afterwards you can enable power saving
967features of your hard disk with <c>hdparm</c> as the second alternative.
968</p>
969
805<body> 970</body>
971</section>
972<section>
973<title>Increasing idle time - laptop-mode</title>
974<body>
806 975
807<p>
808Let's bring the hard disk to sleep as early as possible whenever it is not
809needed. I'll show you two possibilities to do it. First <c>cpudyn</c> supports
810Disk Power Management. Uncomment the lines in the "Disk Options" section in
811<path>/etc/conf.d/cpudyn</path>. To put your first disk to sleep after 60
812seconds of no activity, you would modify it like this:
813</p> 976<p>
814 977Recent kernels (2.6.6 and greater, recent 2.4 ones and others with patches)
815<pre caption="Using cpudyn for disk standby"> 978include the so-called <c>laptop-mode</c>. When activated, dirty buffers are
816<comment>################################################ 979written to disk on read calls or after 10 minutes (instead of 30 seconds). This
817# DISK OPTIONS 980minimizes the time the hard disk needs to be spun up.
818# (disabled by default)
819################################################
820
821#
822# Timeout to put the disk in standby mode if there was no
823# io during that period (in seconds)
824#
825</comment>
826TIMEOUT=60
827<comment>
828#
829# Specified disks to spindown (comma separated devices)
830#
831</comment>
832DISKS=/dev/hda
833</pre>
834
835<p> 981</p>
982
983<pre caption="Automated start of laptop-mode">
984# <i>emerge laptop-mode-tools</i>
985</pre>
986
987<p>
988<c>laptop-mode-tools</c> has its configuration file in
989<path>/etc/laptop-mode/laptop-mode.conf</path>. Adjust it the way you like it,
990it's well commented. Run <c>rc-update add laptop_mode battery</c> to start it
991automatically.
992</p>
993
994<p>
995Recent versions (1.11 and later) of laptop-mode-tools include a new tool
996<c>lm-profiler</c>. It will monitor your system's disk usage and running
997network services and suggests to disable unneeded ones. You can either disable
998them through laptop-mode-tools builtin runlevel support (which will be reverted
999by Gentoo's <c>/sbin/rc</c>) or use your <c>default</c>/<c>battery</c>
1000runlevels (recommended).
1001</p>
1002
1003<pre caption="Sample output from running lm-profiler">
1004# <i>lm-profiler</i>
1005Profiling session started.
1006Time remaining: 600 seconds
1007[4296896.602000] amarokapp
1008Time remaining: 599 seconds
1009[4296897.714000] sort
1010[4296897.970000] mv
1011Time remaining: 598 seconds
1012Time remaining: 597 seconds
1013[4296900.482000] reiserfs/0
1014</pre>
1015
1016<p>
1017After profiling your system for ten minutes, lm-profiler will present a list of
1018services which might have caused disk accesses during that time.
1019</p>
1020
1021<pre caption="lm-profiler suggests to disable some services">
1022Program: "atd"
1023Reason: standard recommendation (program may not be running)
1024Init script: /etc/init.d/atd (GUESSED)
1025
1026Do you want to disable this service in battery mode? [y/N]: <i>n</i>
1027</pre>
1028
1029<p>
1030To disable atd as suggested in the example above, you would run <c>rc-update
1031del atd battery</c>. Be careful not to disable services that are needed for
1032your system to run properly - <c>lm-profiler</c> is likely to generate some
1033false positives. Do not disable a service if you are unsure whether it's
1034needed.
1035</p>
1036
1037</body>
1038</section>
1039<section>
1040<title>Limiting Write Accesses</title>
1041<body>
1042
1043<p>
1044If you don't want to use laptop-mode, you must take special care to disable
1045services that write to your disk frequently - <c>syslogd</c> is a good
1046candidate, for example. You probably don't want to shut it down completely, but
1047it's possible to modify the config file so that "unnecessary" things don't get
1048logged and thus don't create disk traffic. <c>Cups</c> writes to disk
1049periodically, so consider shutting it down and only enable it manually when
1050needed.
1051</p>
1052
1053<pre caption="Disabling cups in battery mode">
1054# <i>rc-update del cupsd battery</i>
1055</pre>
1056
1057<p>
1058You can also use <c>lm-profiler</c> from laptop-mode-tools (see above) to find
1059services to disable. Once you eliminated all of them, go on with configuring
1060hdparm.
1061</p>
1062
1063</body>
1064</section>
1065<section>
1066<title>hdparm</title>
1067<body>
1068
1069<p>
836The second possibility is using a small script and hdparm. Create 1070The second possibility is using a small script and <c>hdparm</c>. Skip this if
837<path>/etc/init.d/pm.hda</path> like this: 1071you are using laptop-mode. Otherwise, create <path>/etc/init.d/pmg_hda</path>:
838</p> 1072</p>
839 1073
840<pre caption="Using hdparm for disk standby"> 1074<pre caption="Using hdparm for disk standby">
841#!/sbin/runscript 1075#!/sbin/runscript
842 1076
843depend() { 1077depend() {
844 after hdparm 1078after hdparm
845} 1079}
846 1080
847start() { 1081start() {
848 ebegin "Activating Power Management for Hard Drives" 1082ebegin "Activating Power Management for Hard Drives"
849 hdparm -q -S12 /dev/hda 1083hdparm -q -S12 /dev/hda
850 eend $? 1084eend $?
851} 1085}
852 1086
853stop () { 1087stop () {
854 ebegin "Deactivating Power Management for Hard Drives" 1088ebegin "Deactivating Power Management for Hard Drives"
855 hdparm -q -S253 /dev/hda 1089hdparm -q -S253 /dev/hda
856 eend $? 1090eend $?
857} 1091}
858</pre> 1092</pre>
859 1093
860<p> 1094<p>
861See <c>man hdparm</c> for the options. If your script is ready, add it to the 1095See <c>man hdparm</c> for the options. If your script is ready, add it to the
862battery runlevel. 1096battery runlevel.
863</p> 1097</p>
864 1098
865<pre caption="Automate disk standby settings"> 1099<pre caption="Automate disk standby settings">
866# <i>chmod +x /etc/init.d/pm.hda</i> 1100# <i>chmod +x /etc/init.d/pmg_hda</i>
867# <i>/sbin/depscan.sh</i> 1101# <i>/sbin/depscan.sh</i>
868# <i>rc-update add pm.hda battery</i> 1102# <i>rc-update add pmg_hda battery</i>
869</pre> 1103</pre>
870 1104
871<impo> 1105<impo>
872Be careful with sleep/spin down settings of your hard drive. Setting it to 1106Be careful with sleep/spin down settings of your hard drive. Setting it to
873small values might wear out your drive and lose warranty. 1107small values might wear out your drive and lose warranty.
874</impo> 1108</impo>
875 1109
876</body> 1110</body>
877</section> 1111</section>
878<section> 1112<section>
879<title>Increasing idle time - laptop-mode</title>
880<body>
881
882<p>
883Recent kernels (2.6.6 and greater, recent 2.4 ones and others with patches)
884include the so-called <e>laptop-mode</e>. When activated, dirty buffers are
885written to disk on read calls or after 10 minutes (instead of 30 seconds). This
886minimizes the time the hard disk needs to be spun up.
887</p>
888
889<pre caption="Automated start of laptop-mode">
890# <i>emerge laptop-mode-tools</i>
891</pre>
892
893<p>
894<c>laptop-mode-tools</c> has it's configuration file in
895<path>/etc/laptop-mode/laptop-mode.conf</path>. Adjust it the way you like it,
896it's well commented. Run <c>rc-update add laptop_mode battery</c> to start it
897automatically.
898</p>
899
900</body>
901</section>
902<section>
903<title>Other tricks</title> 1113<title>Other tricks</title>
904<body> 1114<body>
905
906<p>
907Besides putting your disk to sleep state as early as possible, it is a good
908idea to minimize disk accesses. Have a look at processes that write to your
909disk frequently - the syslogd is a good candidate. You probably don't want to
910shut it down completely, but it's possible to modify the config file so that
911"unnecessary" things don't get logged and thus don't create disk traffic. Cups
912writes to disk periodically, so consider shutting it down and only enable it
913manually when needed.
914</p>
915
916<pre caption="Disabling cups in battery mode">
917# <i>rc-update del cupsd battery</i>
918</pre>
919 1115
920<p> 1116<p>
921Another possibility is to deactivate swap in battery mode. Before writing a 1117Another possibility is to deactivate swap in battery mode. Before writing a
922swapon/swapoff switcher, make sure there is enough RAM and swap isn't used 1118swapon/swapoff switcher, make sure there is enough RAM and swap isn't used
923heavily, otherwise you'll be in big problems. 1119heavily, otherwise you'll be in big problems.
924</p> 1120</p>
925 1121
926<p> 1122<p>
927If you don't want to use laptop-mode, it's still possible to minimize disk 1123If you don't want to use laptop-mode, it's still possible to minimize disk
928access by mounting certain directories as <e>tmpfs</e> - write accesses are not 1124access by mounting certain directories as <c>tmpfs</c> - write accesses are not
929stored on a disk, but in main memory and get lost with unmounting. Often it's 1125stored on a disk, but in main memory and get lost with unmounting. Often it's
930useful to mount <path>/tmp</path> like this - you don't have to pay special 1126useful to mount <path>/tmp</path> like this - you don't have to pay special
931attention as it gets cleared on every reboot regardless whether it was mounted 1127attention as it gets cleared on every reboot regardless whether it was mounted
932on disk or in RAM. Just make sure you have enough RAM and no program (like a 1128on disk or in RAM. Just make sure you have enough RAM and no program (like a
933download client or compress utility) needs extraordinary much space in 1129download client or compress utility) needs extraordinary much space in
939none /tmp tmpfs size=32m 0 0 1135none /tmp tmpfs size=32m 0 0
940</pre> 1136</pre>
941 1137
942<warn> 1138<warn>
943Pay attention to the size parameter and modify it for your system. If you're 1139Pay attention to the size parameter and modify it for your system. If you're
944unsure, don't try this at all, it can become a perfomance bottleneck easily. In 1140unsure, don't try this at all, it can become a performance bottleneck easily. In
945case you want to mount <path>/var/log</path> like this, make sure to merge the 1141case you want to mount <path>/var/log</path> like this, make sure to merge the
946log files to disk before unmounting. They are essential. Don't attempt to mount 1142log files to disk before unmounting. They are essential. Don't attempt to mount
947/var/tmp like this. Portage uses it for compiling... 1143<path>/var/tmp</path> like this. Portage uses it for compiling...
948</warn> 1144</warn>
949 1145
950</body> 1146</body>
951</section> 1147</section>
952</chapter> 1148</chapter>
953 1149
954<chapter> 1150<chapter>
955<title>Power Management for other devices</title> 1151<title>Power Management For Other Devices</title>
1152<section>
1153<title>Graphics Cards</title>
1154<body>
1155
1156<p>
1157In case you own an ATI graphics card supporting PowerPlay (dynamic clock
1158scaling for the the graphics processing unit GPU), you can activate this
1159feature in X.org. Open <path>/etc/X11/xorg.conf</path> and add (or enable) the
1160<c>DynamicClocks</c> option in the Device section. Please notice that this
1161feature will lead to crashes on some systems.
1162</p>
1163
1164<pre caption="Enabling ATI PowerPlay support in X.org">
1165Section "Device"
1166[...]
1167Option "DynamicClocks" "on"
1168EndSection
1169</pre>
1170
1171</body>
1172</section>
956<section> 1173<section>
957<title>Wireless Power Management</title> 1174<title>Wireless Power Management</title>
958<body> 1175<body>
959 1176
960<p> 1177<p>
961Wireless LAN cards consume quite a few energy. Put them in Power Management 1178Wireless LAN cards consume quite a bit of energy. Put them in Power Management
962mode in analogy to the pm.hda script. 1179mode in analogy to the <c>pmg_hda</c> script.
963</p> 1180</p>
1181
1182<note>
1183This script assumes your wireless interface is called <c>wlan0</c>; replace
1184this with the actual name of your interface.
1185</note>
964 1186
965<pre caption="WLAN Power Management automated"> 1187<pre caption="WLAN Power Management automated">
966#!/sbin/runscript 1188#!/sbin/runscript
967start() { 1189start() {
968 ebegin "Activating Power Management for Wireless LAN" 1190 ebegin "Activating Power Management for Wireless LAN"
969 iwconfig wlan0 power on power max period 3 1191 iwconfig wlan0 power on
970 eend $? 1192 eend $?
971} 1193}
972 1194
973stop () { 1195stop () {
974 ebegin "Deactivating Power Management for Wireless LAN" 1196 ebegin "Deactivating Power Management for Wireless LAN"
976 eend $? 1198 eend $?
977} 1199}
978</pre> 1200</pre>
979 1201
980<p> 1202<p>
981Starting this script will put wlan0 in Power Management mode, going to sleep at 1203Starting this script will activate power saving features for wlan0. Save it as
982the latest three seconds after no traffic.
983Save it as <path>/etc/init.d/pm.wlan0</path> and add it to the battery runlevel 1204<path>/etc/init.d/pmg_wlan0</path> and add it to the battery runlevel like the
984like the disk script above. See <c>man iwconfig</c> for details and more 1205disk script above. See <c>man iwconfig</c> for details and more options like
985options. If your driver and access point support changing the beacon time, this 1206the period between wakeups or timeout settings. If your driver and access point
986is a good starting point to save even more energy. 1207support changing the beacon time, this is a good starting point to save even
1208more energy.
987</p> 1209</p>
988 1210
989<pre caption="Power Management for WLAN"> 1211<pre caption="Power Management for WLAN">
990# <i>chmod +x /etc/init.d/pm.wlan0</i> 1212# <i>chmod +x /etc/init.d/pmg_wlan0</i>
991# <i>/sbin/depscan.sh</i> 1213# <i>/sbin/depscan.sh</i>
992# <i>rc-update add pm.wlan0 battery</i> 1214# <i>rc-update add pmg_wlan0 battery</i>
993</pre> 1215</pre>
994 1216
995</body> 1217</body>
996</section> 1218</section>
997<section> 1219<section>
1002There are two problems with USB devices regarding energy consumption: First, 1224There are two problems with USB devices regarding energy consumption: First,
1003devices like USB mice, digital cameras or USB sticks consume energy while 1225devices like USB mice, digital cameras or USB sticks consume energy while
1004plugged in. You cannot avoid this (nevertheless remove them in case they're not 1226plugged in. You cannot avoid this (nevertheless remove them in case they're not
1005needed). Second, when there are USB devices plugged in, the USB host controller 1227needed). Second, when there are USB devices plugged in, the USB host controller
1006periodically accesses the bus which in turn prevents the CPU from going into 1228periodically accesses the bus which in turn prevents the CPU from going into
1007C3/4 sleep mode. The OS answer to this problem is the so called "USB selective 1229sleep mode. The kernel offers an experimental option to enable suspension of
1008suspend", which has not yet been implemented in the kernel. USB selective 1230USB devices through driver calls or one of the <path>power/state</path> files
1009suspend only allows bus accesses in case the device is in use. The cruel 1231in <path>/sys</path>.
1010workaround until it's implemented is as following: Compile USB support and 1232</p>
1011devices as modules and remove them via a script while they are not in use (e.g. 1233
1012when closing the lid). 1234<pre caption="Enabling USB suspend support in the kernel">
1235Device Drivers
1236 USB support
1237 [*] Support for Host-side USB
1238 [*] USB suspend/resume (EXPERIMENTAL)
1013</p> 1239</pre>
1014 1240
1015</body> 1241</body>
1016</section> 1242</section>
1017</chapter> 1243</chapter>
1018 1244
1019<chapter> 1245<chapter>
1020<title>Sleep states: sleep, standby, suspend to disk</title> 1246<title>Sleep States: sleep, standby, and suspend to disk</title>
1021<section> 1247<section>
1022<title>Overview</title>
1023<body> 1248<body>
1024 1249
1025<p> 1250<p>
1026ACPI defines different sleep states. The more important ones are 1251ACPI defines different sleep states. The more important ones are
1027</p> 1252</p>
1028 1253
1029<ul> 1254<ul>
1030 <li>S1 aka Standby</li> 1255 <li>S1 aka Standby</li>
1031 <li>S3 aka Suspend to RAM aka Sleep</li> 1256 <li>S3 aka Suspend to RAM aka Sleep</li>
1032 <li>S4 aka Suspend to Disk aka Hibernate</li> 1257 <li>S4 aka Suspend to Disk aka Hibernate</li>
1033</ul> 1258</ul>
1034 1259
1038</p> 1263</p>
1039 1264
1040</body> 1265</body>
1041</section> 1266</section>
1042<section> 1267<section>
1043<title>Sleep, Standby &amp; Hibernate</title> 1268<title>Sleep (S3)</title>
1044<body> 1269<body>
1045 1270
1046<p> 1271<p>
1047The ACPI support for these sleep states is marked as experimental for good 1272The ACPI support for these sleep states is marked experimental for good reason.
1048reason. APM sleep states seem to be more stable, however you can't use APM and 1273APM sleep states seem to be more stable, however you can't use APM and ACPI
1049ACPI together. 1274together.
1275</p>
1276
1277<pre caption="Kernel configuration for the various suspend types">
1278 Power Management Options ---&gt;
1279 [*] Power Management support
1280 ACPI (Advanced Configuration and Power Interface) Support ---&gt;
1281 [*] ACPI Support
1282 [*] Sleep States
1283</pre>
1284
1285<p>
1286Once your kernel is properly configured, you can use the
1287<c>hibernate-script</c> to activate suspend or sleep mode. Let's install that
1288first.
1289</p>
1290
1291<pre caption="Installing the hibernate-script">
1292# <i>emerge hibernate-script</i>
1293</pre>
1294
1295<p>
1296Some configuration has to be done in <path>/etc/hibernate</path> The default
1297package introduces two configuration files <path>hibernate.conf</path> and
1298<path>ram.conf</path>.
1299</p>
1300
1301<p>
1302To configure sleep, edit <path>ram.conf</path> in <path>/etc/hibernate</path>.
1303<c>UseSysfsPowerState mem</c> is already setup correctly, but you have to go
1304through the rest of the configuration file and set it up for your system. The
1305comments and option names will guide you. If you use nfs or samba shares over
1306the network, make sure to shutdown the appropriate init scripts to avoid
1307timeouts.
1308</p>
1309
1310<p>
1311Ready? Now is the last chance to backup any data you want to keep after
1312executing the next command. Notice that you probably have to hit a special key
1313like <c>Fn</c> to resume from sleep.
1314</p>
1315
1316<pre caption="Calling sleep">
1317# <i>hibernate-ram</i>
1318</pre>
1319
1320<p>
1321If you're still reading, it seems to work. You can also setup standby (S1) in a
1322similar way by copying <path>ram.conf</path> to <path>standby.conf</path> and
1323creating a symlink <path>/usr/sbin/hibernate-standby</path> pointing to
1324<path>/usr/sbin/hibernate</path>. S3 and S4 are the more interesting sleep
1325states due to greater energy savings however.
1326</p>
1327
1328</body>
1329</section>
1330<section>
1331<title>Hibernate (S4)</title>
1332<body>
1333
1334<p>
1335This section introduces hibernation, where a snapshot of the running system is
1336written to disk before powering off. On resume, the snapshot is loaded and you
1337can go on working at exactly the point you called hibernate before.
1050</p> 1338</p>
1051 1339
1052<warn> 1340<warn>
1053Altough sleep state support is improving much, it's still rather experimental. 1341Don't exchange non hot-pluggable hardware when suspended. Don't attempt to load
1054At last I got swsusp2 and suspend to RAM to work, but be warned: This will very 1342a snapshot with a different kernel image than the one it was created with.
1055likely not work but damage your data/system. 1343Shutdown any NFS or samba server/client before hibernating.
1056</warn> 1344</warn>
1057 1345
1058<p> 1346<p>
1059There are currently three implementations for S4. The original one is swsusp, 1347There are two different implementations for S4. The original one is swsusp,
1060then there is swsusp2 which has the nicest interface (including bootsplash 1348then there is the newer suspend2 with a nicer interface (including fbsplash
1061support), but requires manual kernel patching. Last not least we have 1349support). A <uri link="http://suspend2.net/features.html#compare"> feature
1062Suspend-to-Disk, a fork of swsusp. 1350comparison</uri> is available at the <uri link="http://suspend2.net"> suspend2
1063</p> 1351Homepage</uri>. There used to be Suspend-to-Disk (pmdisk), a fork of swsusp,
1064 1352but it has been merged back.
1065<p> 1353</p>
1066If this confused you, have a look at a <uri 1354
1067link="http://softwaresuspend.berlios.de/features.html#compare">feature
1068comparison</uri>. If you still are confused and don't know which one to choose,
1069first give swsusp2 a try, it looks most promising.
1070</p> 1355<p>
1071 1356Suspend2 is not included in the mainline kernel yet, therefore you either have
1357to patch your kernel sources with the patches provided by <uri
1358link="http://suspend2.net">suspend2.net</uri> or use
1359<c>sys-kernel/suspend2-sources</c>.
1072<p> 1360</p>
1073The kernel part for this is as following: 1361
1362<p>
1363The kernel part for both swusp and suspend2 is as follows:
1074</p> 1364</p>
1075 1365
1076<pre caption="Kernel configuration for the various suspend types"> 1366<pre caption="Kernel configuration for the various suspend types">
1077Power Management Options ---&gt; 1367Power Management Options ---&gt;
1078
1079 <comment>(sleep and standby)</comment>
1080 ACPI( Advanced Configuration and Power Interface ) Support --->
1081 [*] ACPI Support
1082 [*] Sleep States
1083
1084 <comment>(hibernate with swsusp)</comment> 1368 <comment>(hibernate with swsusp)</comment>
1085 [*] Software Suspend (EXPERIMENTAL) 1369 [*] Software Suspend
1086 1370 <comment>(replace /dev/SWAP with your swap partition)</comment>
1371 (/dev/SWAP) Default resume partition
1372
1087 <comment>(hibernate with swsusp2)</comment> 1373 <comment>(hibernate with suspend2)</comment>
1088 Software Suspend 2 1374 Software Suspend 2
1089 --- Image Storage (you need at least one writer) 1375 --- Image Storage (you need at least one writer)
1376 [*] File Writer
1090 [*] Swap Writer 1377 [*] Swap Writer
1091 --- Page Transformers 1378 --- General Options
1092 [*] LZF image compression 1379 [*] LZF image compression
1380 <comment>(replace /dev/SWAP with your swap partition)</comment>
1093 (/dev/"your-swap-here") Default resume device name 1381 (swap:/dev/SWAP) Default resume device name
1094 1382 [ ] Allow Keep Image Mode
1095 <comment>(hibernate with Suspend-to-Disk)</comment>
1096 [*] Suspend-to-Disk Suport
1097 (/dev/"your-swap-here") Default resume partition
1098</pre> 1383</pre>
1099 1384
1100<p>
1101Compile your kernel with the appropriate options enabled and issue <c>cat
1102/proc/acpi/sleep</c> for 2.4 series respectively <c>cat /sys/power/state</c>
1103for 2.6 to find out what is supported. The latter gives me <c>standby mem
1104disk</c>. For swsusp, the kernel parameter <c>resume=/dev/"your-swap-here"</c>
1105has to be appended. If booting is not possible due to a broken image, use
1106<c>noresume</c> for swsusp, <c>pmdisk=off</c> for Suspend-to-Disk and
1107<c>noresume2</c> for swsusp2.
1108</p> 1385<p>
1109 1386The configuration for swsusp is rather easy. If you didn't store the location
1387of your swap partition in the kernel config, you can also pass it as a
1388parameter with the <c>resume=/dev/SWAP</c> directive. If booting is not
1389possible due to a broken image, use the <c>noresume</c> kernel parameter. The
1390<c>hibernate-cleanup</c> init script invalidates swsusp images during the boot
1391process.
1110<p> 1392</p>
1111To put your system in one of the sleep states, use 1393
1394<pre caption="Invalidating swsusp images during the boot process">
1395# <i>rc-update add hibernate-cleanup boot</i>
1396</pre>
1397
1112</p> 1398<p>
1113 1399To activate hibernate with swsusp, use the hibernate script and set
1114<pre caption="Activating sleep states"> 1400<c>UseSysfsPowerState disk</c> in <path>/etc/hibernate/hibernate.conf</path>.
1115<comment>(kernel 2.4 series)</comment>
1116# <i>echo 1 &gt; /proc/acpi/sleep</i> <comment>(standby)</comment>
1117# <i>echo 3 &gt; /proc/acpi/sleep</i> <comment>(sleep)</comment>
1118
1119<comment>(kernel 2.6 series)</comment>
1120# <i>echo -n standby &gt; /sys/power/state</i> <comment>(standby)</comment>
1121# <i>echo -n mem &gt; /sys/power/state</i> <comment>(sleep)</comment>
1122
1123<comment>(swsusp)</comment>
1124# <i>echo 4 &gt; /proc/acpi/sleep</i> <comment>(hibernate)</comment>
1125
1126<comment>(Suspend-to-Disk)</comment>
1127# <i>echo -n disk &gt; /sys/power/state</i> <comment>(hibernate)</comment>
1128
1129<comment>(swsusp2)</comment>
1130# <i>/usr/sbin/hibernate</i> <comment>(hibernate, see below)</comment>
1131</pre> 1401</p>
1132 1402
1133<warn> 1403<warn>
1134Backup your data before doing this. Run <c>sync</c> before executing one of the 1404Backup your data before doing this. Run <c>sync</c> before executing one of the
1135commands to have cached data written to disk. First try it outside of X, then 1405commands to have cached data written to disk. First try it outside of X, then
1136with X running, but not logged in. 1406with X running, but not logged in.
1137</warn> 1407</warn>
1138 1408
1139<p> 1409<p>
1140If you experience kernel panics due to uhci or similar, try to compile USB 1410If you experience kernel panics due to uhci or similar, try to compile USB
1141support as module and unload the modules before sending your laptop to sleep 1411support as module and unload the modules before sending your laptop to sleep
1142mode. 1412mode. There are configuration options for this in <path>hibernate.conf</path>
1143</p>
1144
1145<p> 1413</p>
1146While the above should be sufficient to get swsusp and Suspend-to-Disk running
1147(I didn't say working), swsusp2 needs special care.
1148The first thing to do is patching the kernel with the patches provided at <uri
1149link="http://softwaresuspend.berlios.de/">
1150http://softwaresuspend.berlios.de/</uri>. Additionally you've got to emerge
1151<c>hibernate-script</c>. Once it is installed, configure
1152<path>/etc/hibernate/hibernate.conf</path> and try whether it works:
1153</p>
1154 1414
1155<pre caption="Configure hibernation"> 1415<pre caption="Hibernating with swsusp">
1156<i># emerge hibernate-script</i> 1416# <i>nano -w /etc/hibernate.conf</i>
1157<i># $EDITOR /etc/hibernate/hibernate.conf</i> 1417<comment>(Make sure you have a backup of your data)</comment>
1158<comment>(Last chance to backup any data)</comment>
1159<i># hibernate</i> 1418# <i>hibernate</i>
1419</pre>
1420
1421<p>
1422The following section discusses the setup of suspend2 including fbsplash
1423support for a nice graphical progress bar during suspend and resume.
1160</pre> 1424</p>
1425
1426<p>
1427The first part of the configuration is similar to the configuration of swsusp.
1428In case you didn't store the location of your swap partition in the kernel
1429config, you have to pass it as a kernel parameter with the
1430<c>resume2=swap:/dev/SWAP</c> directive. If booting is not possible due to a
1431broken image, append the <c>noresume2</c> parameter. Additionally, the
1432<c>hibernate-cleanup</c> init script invalidates suspend2 images during the
1433boot process.
1434</p>
1435
1436<pre caption="Invalidating suspend2 images during the boot process">
1437# <i>rc-update add hibernate-cleanup boot</i>
1438</pre>
1439
1440<p>
1441Now edit <path>/etc/hibernate/hibernate.conf</path>, enable the <c>suspend2</c>
1442section and comment everything in the <c>sysfs_power_state</c> and
1443<c>acpi_sleep</c> sections. Do not enable the <c>fbsplash</c> part in global
1444options yet.
1445</p>
1446
1447<pre caption="Hibernating with suspend2">
1448# <i>nano -w /etc/hibernate.conf</i>
1449<comment>(Make sure you have a backup of your data)</comment>
1450# <i>hibernate</i>
1451</pre>
1452
1453<p>
1454Please configure <c>fbsplash</c> now if you didn't do already. To enable
1455fbsplash support during hibernation, the <c>sys-apps/suspend2-userui</c>
1456package is needed. Additionally, you've got to enable the <c>fbsplash</c> USE
1457flag.
1458</p>
1459
1460<pre caption="Installing suspend2-userui">
1461# <i>mkdir -p /etc/portage</i>
1462# <i>echo "sys-apps/suspend2-userui fbsplash" >> /etc/portage/package.use</i>
1463# <i>emerge suspend2-userui</i>
1464</pre>
1465
1466<p>
1467The ebuild tells you to make a symlink to the theme you want to use. For
1468example, to use the <c>livecd-2005.1</c> theme, run the following command:
1469</p>
1470
1471<pre caption="Using the livecd-2005.1 theme during hibernation">
1472# <i>ln -sfn /etc/splash/livecd-2005.1 /etc/splash/suspend2</i>
1473</pre>
1474
1475<p>
1476If you don't want a black screen in the first part of the resume process, you
1477have to add the <c>suspend2ui_fbsplash</c> tool to your initrd image. Assuming
1478you created the initrd image with <c>splash_geninitramfs</c> and saved it as
1479<path>/boot/fbsplash-emergence-1024x768</path>, here's how to do that.
1480</p>
1481
1482<pre caption="Adding suspend2ui_fbsplash to an initrd image">
1483# <i>mount /boot</i>
1484# <i>mkdir ~/initrd.d</i>
1485# <i>cp /boot/fbsplash-emergence-1024x768 ~/initrd.d/</i>
1486# <i>cd ~/initrd.d</i>
1487# <i>gunzip -c fbsplash-emergence-1024x768 | cpio -idm --quiet -H newc</i>
1488# <i>rm fbsplash-emergence-1024x768</i>
1489# <i>cp /usr/sbin/suspend2ui_fbsplash sbin/</i>
1490# <i>find . | cpio --quiet --dereference -o -H newc | gzip -9 > /boot/fbsplash-suspend2-emergence-1024x768</i>
1491</pre>
1492
1493<p>
1494Afterwards adjust <path>grub.conf</path> respectively <path>lilo.conf</path> so
1495that your suspend2 kernel uses
1496<path>/boot/fbsplash-suspend2-emergence-1024x768</path> as initrd image. You
1497can now test a dry run to see if everything is setup correctly.
1498</p>
1499
1500<pre caption="Test run for fbsplash hibernation">
1501# <i>suspend2ui_fbsplash -t</i>
1502</pre>
1503
1504<p>
1505Afterwards open <path>/etc/hibernate/hibernate.conf</path> again and activate
1506the fbsplash options. Execute <c>hibernate</c> and enjoy.
1507</p>
1161 1508
1162</body> 1509</body>
1163</section> 1510</section>
1164</chapter> 1511</chapter>
1165 1512
1166<chapter> 1513<chapter>
1167<title>Troubleshooting</title> 1514<title>Troubleshooting</title>
1168<section> 1515<section>
1169<title>If things go wrong...</title>
1170<body> 1516<body>
1171 1517
1172<p> 1518<p>
1173<e>Q:</e> I'm trying to change the CPU frequency, but 1519<e>Q:</e> I'm trying to change the CPU frequency, but
1174<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor</path> does not 1520<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor</path> does not
1199Try to update the BIOS, especially if a broken DSDT is reported. You can also 1545Try to update the BIOS, especially if a broken DSDT is reported. You can also
1200try to fix it yourself (which is beyond the scope of this guide). 1546try to fix it yourself (which is beyond the scope of this guide).
1201</p> 1547</p>
1202 1548
1203<p> 1549<p>
1204<e>Q:</e> My laptop supports frequency scaling, but according to /proc/cpuinfo 1550<e>Q:</e> My laptop supports frequency scaling, but according to
1205the speed never changes. 1551<path>/proc/cpuinfo</path> the speed never changes.
1206</p> 1552</p>
1207 1553
1208<p> 1554<p>
1209<e>A:</e> Probably you have activated symmetric multiprocessing support 1555<e>A:</e> Probably you have activated symmetric multiprocessing support
1210(CONFIG_SMP) in your kernel. Deactivate it and it should work. Some older 1556(CONFIG_SMP) in your kernel. Deactivate it and it should work. Some older
1211kernels had a bug causing this. In that case, run <c>emerge x86info</c>, 1557kernels had a bug causing this. In that case, run <c>emerge x86info</c>, update
1212update your kernel as asked and check the current frequency with 1558your kernel as asked and check the current frequency with
1213<c>x86info -mhz</c>. 1559<c>x86info -mhz</c>.
1214</p> 1560</p>
1215 1561
1216<p> 1562<p>
1217<e>Q:</e> I can change the CPU frequency, but the range is not as wide as in 1563<e>Q:</e> I can change the CPU frequency, but the range is not as wide as in
1256<e>A:</e> Check that battery support is compiled into your kernel. If you use 1602<e>A:</e> Check that battery support is compiled into your kernel. If you use
1257it as a module, make sure the module is loaded. 1603it as a module, make sure the module is loaded.
1258</p> 1604</p>
1259 1605
1260<p> 1606<p>
1607<e>Q:</e> My system logger reports things like "logger: ACPI group battery /
1608action battery is not defined".
1609</p>
1610
1611<p>
1612<e>A:</e> This message is generated by the <path>/etc/acpi/default.sh</path>
1613script that is shipped with acpid. You can safely ignore it. If you like to get
1614rid of it, you can comment the appropriate line in
1615<path>/etc/acpi/default.sh</path> as shown below:
1616</p>
1617
1618<pre caption="Disabling warnings about unknown acpi events">
1619 *) # logger "ACPI action $action is not defined"
1620</pre>
1621
1622<p>
1261<e>Q:</e> I have a Dell Inspiron 51XX and I don't get any ACPI events. 1623<e>Q:</e> I have a Dell Inspiron 51XX and I don't get any ACPI events.
1262</p> 1624</p>
1263 1625
1264<p> 1626<p>
1265<e>A:</e> This seems to be a kernel bug. Read on <uri 1627<e>A:</e> This seems to be a kernel bug. Read on <uri
1266link="http://bugme.osdl.org/show_bug.cgi?id=1752">here</uri>. 1628link="http://bugme.osdl.org/show_bug.cgi?id=1752">here</uri>.
1267</p> 1629</p>
1268 1630
1269<p> 1631<p>
1632<e>Q:</e> I activated the <c>DynamicClocks</c> option in <path>xorg.conf</path>
1633and now X.org crashes / the screen stays black / my laptop doesn't shutdown
1634properly.
1635</p>
1636
1637<p>
1638<e>A:</e> This happens on some systems. You have to disable
1639<c>DynamicClocks</c>.
1640</p>
1641
1642<p>
1643<e>Q:</e> I want to use suspend2, but it tells me my swap partition is too
1644small. Resizing is not an option.
1645</p>
1646
1647<p>
1648<e>A:</e> If there is enough free space on your system, you can use the
1649filewriter instead of the swapwriter. The <c>hibernate-script</c> supports it
1650as well. More information can be found in
1651<path>/usr/src/linux/Documentation/power/suspend2.txt</path>.
1652</p>
1653
1654<p>
1270<e>Q:</e> I just bought a brand new battery, but it only lasts for some 1655<e>Q:</e> I just bought a brand new battery, but it only lasts for some
1271minutes! What am I doing wrong? 1656minutes! What am I doing wrong?
1272</p> 1657</p>
1273 1658
1274<p> 1659<p>
1275<e>A:</e> First follow your manufacturer's advice on how to charge the battery 1660<e>A:</e> First follow your manufacturer's advice on how to charge the battery
1276correctly. 1661correctly.
1277</p> 1662</p>
1278 1663
1279<p> 1664<p>
1280<e>Q:</e> The above didn't help. What should I do then? 1665<e>Q:</e> The above didn't help. What should I do then?
1281</p> 1666</p>
1298<p> 1683<p>
1299<e>Q:</e> My problem is not listed above. Where should I go next? 1684<e>Q:</e> My problem is not listed above. Where should I go next?
1300</p> 1685</p>
1301 1686
1302<p> 1687<p>
1303<e>A:</e> Don't fear to contact me, <mail link="fragfred@gmx.de">Dennis 1688<e>A:</e> Don't fear to contact me, <mail link="earthwings@gentoo.org">Dennis
1304Nienhüser</mail>, directly. 1689Nienhüser</mail>, directly. The <uri link="http://forums.gentoo.org">Gentoo
1690Forums</uri> are a good place to get help as well. If you prefer IRC, try the
1691<c>#gentoo-laptop</c> channel at <uri
1692link="irc://irc.freenode.net">irc.freenode.net</uri>.
1305</p> 1693</p>
1306 1694
1307</body> 1695</body>
1308</section> 1696</section>
1309</chapter> 1697</chapter>

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