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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 1.8 2005/01/17 10:10:23 swift Exp $ --> 3<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/power-management-guide.xml,v 1.45 2011/03/02 09:18:04 nightmorph Exp $ -->
4<guide link="power-management-guide.xml"> 4
5<guide>
5<title>Power Management Guide</title> 6<title>Power Management Guide</title>
6 7
7<author title="Author"> 8<author title="Author">
8 <mail link="fragfred@gmx.de">Dennis Nienhüser</mail> 9 <mail link="earthwings@gentoo.org">Dennis Nienhüser</mail>
10</author>
11<author title="Editor">
12 <mail link="chriswhite@gentoo.org">Chris White</mail>
13</author>
14<author title="Editor">
15 <mail link="nightmorph"/>
9</author> 16</author>
10 17
11<abstract> 18<abstract>
12Power Management is the key to extend battery run time on mobile systems like 19Power Management is the key to extend battery run time on mobile systems like
13laptops. This guide assists you setting it up on your laptop. 20laptops. This guide assists you setting it up on your laptop.
14</abstract> 21</abstract>
15 22
16<!-- The content of this document is licensed under the CC-BY-SA license --> 23<!-- The content of this document is licensed under the CC-BY-SA license -->
17<!-- See http://creativecommons.org/licenses/by-sa/2.0 --> 24<!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
18<license/> 25<license/>
19 26
20<version>1.18</version> 27<version>2</version>
21<date>January 05, 2005</date> 28<date>2011-03-02</date>
22 29
23<chapter> 30<chapter>
24<title>Introduction</title> 31<title>Introduction</title>
25
26<section> 32<section>
27<title>Why Power Management?</title>
28
29<body> 33<body>
30 34
31<p> 35<p>
32Capacity and lifetime of laptop batteries has improved much in the last years. 36Capacity and lifetime of laptop batteries have improved much in the last years.
33Nevertheless modern processors consume much more energy than older ones and 37Nevertheless modern processors consume much more energy than older ones and
34each laptop generation introduces more devices hungry for energy. That's why 38each laptop generation introduces more devices hungry for energy. That's why
35Power Management is more important than ever. Increasing battery run time 39Power Management is more important than ever. Increasing battery run time
36doesn't necessarily mean buying another battery. Much can be achieved applying 40doesn't necessarily mean buying another battery. Much can be achieved applying
37intelligent Power Management policies. 41intelligent Power Management policies.
38</p> 42</p>
39 43
40</body> 44</body>
41</section> 45</section>
42
43<section> 46<section>
44<title>A quick overview</title> 47<title>A Quick Overview</title>
45<body> 48<body>
46 49
47<p> 50<p>
48Please notice that this guide describes Power Management for <e>laptops</e>. 51Please notice that this guide describes Power Management for <e>laptops</e>.
49While some sections might also suite for <e>servers</e>, others do not and may 52While some sections might also suite for <e>servers</e>, others do not and may
55As this guide has become rather long, here's a short overview helping you to 58As this guide has become rather long, here's a short overview helping you to
56find your way through it. 59find your way through it.
57</p> 60</p>
58 61
59<p> 62<p>
60The <e>Prerequisites</e> chapter talks about some requirements that should be 63The <uri link="#doc_chap2">Prerequisites</uri> chapter talks about some
61met before any of the following device individual sections will work. This 64requirements that should be met before any of the following device individual
62includes BIOS settings, kernel configuration and some simplifications in user 65sections will work. This includes BIOS settings, kernel configuration and some
63land. The following three chapters focus on devices that typically consume most 66simplifications in user land. The following three chapters focus on devices
64energy - processor, display and hard drive. Each can be configured seperately. 67that typically consume most energy - processor, display and hard drive. Each
65<e>CPU Power Management</e> shows how to adjust the processor's frequency to 68can be configured seperately. <uri link="#doc_chap3">CPU Power Management</uri>
66save a maximum of energy whithout losing too much performance. A few different 69shows how to adjust the processor's frequency to save a maximum of energy
67tricks prevent your hard drive from working unnecessarily often in <e>Disk Power 70without losing too much performance. A few different tricks prevent your hard
71drive from working unnecessarily often in <uri link="#doc_chap5">Disk Power
68Management</e> (decreasing noise level as a nice side effect). Some notes on 72Management</uri> (decreasing noise level as a nice side effect). Some notes on
69Wireless LAN and USB finish the device section in <e>Power Management for other 73graphics cards, Wireless LAN and USB finish the device section in <uri
70devices</e> while another chapter is dedicated to the (rather experimental) 74link="#doc_chap6">Power Management For Other Devices</uri> while another
71<e>sleep states</e>. Last not least <e>Troubleshooting</e> lists common 75chapter is dedicated to the (rather experimental) <uri link="#doc_chap7">sleep
72pitfalls. 76states</uri>. Last not least <uri link="#doc_chap8">Troubleshooting</uri> lists
77common pitfalls.
73</p> 78</p>
74 79
75</body> 80</body>
76</section>
77
78<section> 81</section>
82<section>
79<title>Power Budget for each component</title> 83<title>Power Budget For Each Component</title>
80<body> 84<body>
81 85
82<figure link="/images/energy-budget.png" short="Which component consumes how 86<figure link="/images/energy-budget.png" short="Which component consumes how
83much energy?" caption="Power budget for each component"/> 87much energy?" caption="Power budget for each component"/>
84 88
95</chapter> 99</chapter>
96 100
97<chapter> 101<chapter>
98<title>Prerequisites</title> 102<title>Prerequisites</title>
99<section> 103<section>
100<title>What has to be done first</title>
101<body>
102
103<p>
104Before going into the details on making individual devices Power Management
105aware, make sure certain requirements are met. After controlling the BIOS
106settings, some kernel options want to be enabled - these are in short ACPI,
107sleep states and CPU frequency scaling. As power saving most of the time comes
108along with performance loss or increased latency, it should only be enabled
109when running on batteries. That's where a new runlevel <e>battery</e> comes in
110handy.
111</p>
112
113</body> 104<body>
114</section> 105
106<p>
107Before discussing the details of making individual devices Power Management
108aware, make sure certain requirements are met. After controlling BIOS settings,
109some kernel options want to be enabled - these are in short ACPI, sleep states
110and CPU frequency scaling. As power saving most of the time comes along with
111performance loss or increased latency, it should only be enabled when running
112on batteries. That's where a new runlevel <e>battery</e> comes in handy.
113</p>
114
115</body>
115<section> 116</section>
117<section>
116<title>The BIOS part</title> 118<title>The BIOS Part</title>
117<body> 119<body>
118 120
119<p> 121<p>
120First have a look into your BIOS Power Management settings. The best way is to 122First have a look into your BIOS Power Management settings. The best way is to
121combine BIOS and operating system policies, but for the moment it's better to 123combine BIOS and operating system policies, but for the moment it's better to
125</p> 127</p>
126 128
127</body> 129</body>
128</section> 130</section>
129<section> 131<section>
132<title>Setting USE Flags</title>
133<body>
134
135<p>
136Please check that the <c>acpi</c> USE flag is set in
137<path>/etc/make.conf</path>. Other USE flags that might be interesting for your
138system are <c>apm</c>, <c>lm_sensors</c>, <c>nforce2</c>, <c>nvidia</c>,
139<c>pmu</c>. See <path>/usr/portage/profiles/use*.desc</path> for details. If
140you forgot to set one of these flags, you can recompile affected packages using
141the <c>--newuse</c> flag in <c>emerge</c>, see <c>man emerge</c>.
142</p>
143
144</body>
145</section>
146<section>
130<title>Configuring the kernel</title> 147<title>Configuring The Kernel</title>
131<body> 148<body>
132 149
133<p> 150<p>
134ACPI (Advanced Configuration and Power Interface) support in the kernel is 151ACPI (Advanced Configuration and Power Interface) support in the kernel is
135still work in progress. Using a recent kernel will make sure you'll get the 152still work in progress. Using a recent kernel will make sure you'll get the
136most out of it. 153most out of it.
137</p> 154</p>
138 155
139<p> 156<p>
140In kernel config, activate at least these options: 157There are different kernel sources in Portage. I'd recommend using
158<c>gentoo-sources</c> or <c>tuxonice-sources</c>. The latter contains patches
159for TuxOnIce, see the chapter about <uri link="#doc_chap7">sleep states</uri>
160for more details. When configuring the kernel, activate at least these options:
141</p> 161</p>
142 162
143<pre caption="Minimum kernel setup for Power Management (Kernel 2.6)"> 163<pre caption="Minimum kernel setup for Power Management (Kernel 2.6)">
144Power Management Options ---&gt; 164Power management and ACPI options ---&gt;
145 [*] Power Management Support 165[*] Power Management support
146 [ ] Software Suspend 166 [ ] Software Suspend
147 [ ] Suspend-to-Disk Support
148 167
149 ACPI( Advanced Configuration and Power Interface ) Support ---&gt; 168 ACPI( Advanced Configuration and Power Interface ) Support ---&gt;
150 [*] ACPI Support 169 [ ] Deprecated /proc/acpi/ files
151 [ ] Sleep States 170 [*] AC Adapter
152 &lt;M&gt; AC Adapter 171 [*] Battery
153 &lt;M&gt; Battery
154 &lt;M&gt; Button 172 &lt;M&gt; Button
173 &lt;M&gt; Video
174 [ ] Generic Hotkey
155 &lt;M&gt; Fan 175 &lt;M&gt; Fan
156 &lt;M&gt; Processor 176 &lt;M&gt; Processor
157 &lt;M&gt; Thermal Zone 177 &lt;M&gt; Thermal Zone
158 &lt; &gt; ASUS/Medion Laptop Extras 178 &lt; &gt; ASUS/Medion Laptop Extras
179 &lt; &gt; IBM ThinkPad Laptop Extras
159 &lt; &gt; Toshiba Laptop Extras 180 &lt; &gt; Toshiba Laptop Extras
181 (0) Disable ACPI for systems before Jan 1st this year
160 [ ] Debug Statements 182 [ ] Debug Statements
161 183 [*] Power Management Timer Support
184 &lt; &gt; ACPI0004,PNP0A05 and PNP0A06 Container Driver (EXPERIMENTAL)
185
162 CPU Frequency Scaling ---&gt; 186 CPU Frequency Scaling ---&gt;
163 [*] CPU Frequency scaling 187 [*] CPU Frequency scaling
188 [ ] Enable CPUfreq debugging
189 &lt; &gt; CPU frequency translation statistics
190 [ ] CPU frequency translation statistics details
164 Default CPUFreq governor (userspace) 191 Default CPUFreq governor (userspace)
165 &lt;*&gt; 'performance' governor 192 &lt;*&gt; 'performance' governor
166 &lt;*&gt; 'powersave' governor 193 &lt;*&gt; 'powersave' governor
167 &lt;*&gt; 'ondemand' cpufreq policy governor 194 &lt;*&gt; 'ondemand' cpufreq policy governor
195 &lt;*&gt; 'conservative' cpufreq governor
168 &lt;*&gt; CPU frequency table helpers 196 &lt;*&gt; CPU frequency table helpers
169 &lt;M&gt; ACPI Processor P-States driver 197 &lt;M&gt; ACPI Processor P-States driver
170 &lt;*&gt; <i>CPUFreq driver for your processor</i> 198 &lt;*&gt; <i>CPUFreq driver for your processor</i>
171</pre> 199</pre>
172 200
173<p> 201<p>
174Decide yourself whether you want to enable Software Suspend, Suspend-to-Disk and 202Decide yourself whether you want to enable Software Suspend, and Sleep States
175Sleep States (see below). If you own an ASUS, Medion or Toshiba laptop, enable 203(see below). If you own an ASUS, Medion, IBM Thinkpad or Toshiba laptop, enable
176the appropriate section. Recent kernel versions (2.6.9 and later) include an 204the appropriate section.
177<e>'ondemand' governor</e> for CPU Frequency Scaling, activate it as well when
178using such a kernel.
179</p>
180
181<p> 205</p>
206
207<p>
182The kernel has to know how to enable CPU frequency scaling on your processor. As 208The kernel has to know how to enable CPU frequency scaling on your processor.
183each type of CPU has a different interface, you've got to choose the right 209As each type of CPU has a different interface, you've got to choose the right
184driver for your processor. Be careful here - enabling <e>Intel Pentium 4 clock 210driver for your processor. Be careful here - enabling <c>Intel Pentium 4 clock
185modulation</e> on a Pentium M system will lead to strange results for example. 211modulation</c> on a Pentium M system will lead to strange results for example.
186Consult the kernel documentation if you're unsure which one to take. 212Consult the kernel documentation if you're unsure which one to take.
187</p> 213</p>
188 214
189<p> 215<p>
190Compile your kernel, make sure the right modules get loaded at startup and boot 216Compile your kernel, make sure the right modules get loaded at startup and boot
191into your new ACPI-enabled kernel. Next run <c>emerge sys-apps/acpid</c> to get 217into your new ACPI-enabled kernel. Next run <c>emerge sys-power/acpid</c> to
192the acpi daemon. This one informs you about events like switching from AC to 218get the acpi daemon. This one informs you about events like switching from AC
193battery or closing the lid. Make sure the module <e>button</e> is loaded if you 219to battery or closing the lid. Make sure the modules are loaded if you didn't
194didn't compile it into the kernel and start acpid with <c>/etc/init.d/acpid 220compile them into the kernel and start acpid by executing <c>/etc/init.d/acpid
195start</c>. Run <c>rc-update add acpid default</c> to load it on startup. You'll 221start</c>. Run <c>rc-update add acpid default</c> to load it on startup. You'll
196soon see how to use it. 222soon see how to use it.
197</p> 223</p>
198 224
199<pre caption="Installing acpid"> 225<pre caption="Installing acpid">
200# <i>emerge sys-apps/acpid</i> 226# <i>emerge sys-power/acpid</i>
201# <i>modprobe button</i>
202# <i>/etc/init.d/acpid start</i> 227# <i>/etc/init.d/acpid start</i>
203# <i>rc-update add acpid default</i> 228# <i>rc-update add acpid default</i>
204</pre> 229</pre>
205 230
206</body> 231</body>
207</section> 232</section>
208<section> 233<section>
209<title>Creating a "battery" runlevel</title> 234<title>Creating A "battery" Runlevel</title>
210<body> 235<body>
211 236
212<p> 237<p>
213The default policy will be to enable Power Management only when needed - 238The default policy will be to enable Power Management only when needed -
214running on batteries. To make the switch between AC and battery convenient, 239running on batteries. To make the switch between AC and battery convenient,
215create a runlevel <e>battery</e> that holds all the scripts starting and 240create a runlevel <c>battery</c> that holds all the scripts starting and
216stopping Power Management. 241stopping Power Management.
217</p> 242</p>
218 243
219<note> 244<note>
220You can safely skip this section if you don't like the idea of having another 245You can safely skip this section if you don't like the idea of having another
221runlevel. However, skipping this step will make the rest a bit trickier to set 246runlevel. However, skipping this step will make the rest a bit trickier to set
222up. The next sections assume a runlevel <e>battery</e> exists. 247up. The next sections assume a runlevel <c>battery</c> exists.
223</note> 248</note>
224 249
225<pre caption="Creating a battery runlevel"> 250<pre caption="Creating a battery runlevel">
226# <i>cd /etc/runlevels</i> 251# <i>cd /etc/runlevels</i>
227# <i>cp -a default battery</i> 252# <i>cp -a default battery</i>
228</pre> 253</pre>
229 254
230<p> 255<p>
231Finished. Your new runlevel <e>battery</e> contains everything like 256Finished. Your new runlevel <c>battery</c> contains everything like
232<e>default</e>, but there is no automatic switch between both yet. Time to 257<c>default</c>, but there is no automatic switch between both yet. Time to
233change it. 258change it.
234</p> 259</p>
235 260
236</body> 261</body>
237</section> 262</section>
238<section> 263<section>
239<title>Reacting on ACPI events</title> 264<title>Reacting On ACPI Events</title>
240<body> 265<body>
241 266
242<p> 267<p>
243Typical ACPI events are closing the lid, changing the power source or pressing 268Typical ACPI events are closing the lid, changing the power source or pressing
244the sleep button. An important event is changing the power source, which should 269the sleep button. An important event is changing the power source, which should
245cause a runlevel switch. Create the following files to switch between 270cause a runlevel switch. A small script will take care of it.
246<e>default</e> and <e>battery</e> runlevel depending on the power source: 271</p>
272
247</p> 273<p>
274First you need a script which changes the runlevel to <c>default</c>
275respectively <c>battery</c> depending on the power source. The script uses the
276<c>on_ac_power</c> command from <c>sys-power/pm-utils</c> - make sure the
277package is installed on your system.
278</p>
248 279
280<pre caption="Installing pm-utils">
281# <i>emerge pm-utils</i>
282</pre>
283
284<p>
285You are now able to determine the power source by executing <c>on_ac_power
286&amp;&amp; echo AC available || echo Running on batteries</c> in a shell. The
287script below is responsible for changing runlevels. Save it as
288<path>/etc/acpi/actions/pmg_switch_runlevel.sh</path>.
289</p>
290
249<pre caption="/etc/acpi/switch_runlevel.sh"> 291<pre caption="/etc/acpi/actions/pmg_switch_runlevel.sh">
250#!/bin/bash 292#!/bin/bash
251 293
294<comment># BEGIN configuration</comment>
252RUNLEVEL_AC="default" 295RUNLEVEL_AC="default"
253RUNLEVEL_BATTERY="battery" 296RUNLEVEL_BATTERY="battery"
297<comment># END configuration</comment>
254 298
255function on_ac () { 299
256 if which on_ac_power &amp;> /dev/null 300if [ ! -d "/etc/runlevels/${RUNLEVEL_AC}" ]
301then
302 logger "${0}: Runlevel ${RUNLEVEL_AC} does not exist. Aborting."
303 exit 1
304fi
305
306if [ ! -d "/etc/runlevels/${RUNLEVEL_BATTERY}" ]
307then
308 logger "${0}: Runlevel ${RUNLEVEL_BATTERY} does not exist. Aborting."
309 exit 1
310fi
311
312if on_ac_power
313then
314 if [[ "$(&lt;/var/lib/init.d/softlevel)" != "${RUNLEVEL_AC}" ]]
257 then 315 then
258 on_ac_power 316 logger "Switching to ${RUNLEVEL_AC} runlevel"
259 else 317 /sbin/rc ${RUNLEVEL_AC}
260 grep --quiet on-line /proc/acpi/ac_adapter/*/state
261 fi 318 fi
262}
263
264function SwitchRunlevel () {
265
266 if [ ! -d "/etc/runlevels/${RUNLEVEL_AC}" ]
267 then
268 logger "${0}: Runlevel ${RUNLEVEL_AC} does not exist. Aborting."
269 exit 1
270 fi
271
272
273 if [ ! -d "/etc/runlevels/${RUNLEVEL_BATTERY}" ]
274 then
275 logger "${0}: Runlevel ${RUNLEVEL_BATTERY} does not exist. Aborting."
276 exit 1
277 fi
278
279 if on_ac
280 then if [[ "$(cat /var/lib/init.d/softlevel)" != "${RUNLEVEL_AC}" ]]
281 then
282 logger "Switching to ${RUNLEVEL_AC} runlevel"
283 /sbin/rc ${RUNLEVEL_AC}
284 fi
285 elif [[ "$(cat /var/lib/init.d/softlevel)" != "${RUNLEVEL_BATTERY}" ]] 319elif [[ "$(&lt;/var/lib/init.d/softlevel)" != "${RUNLEVEL_BATTERY}" ]]
286 then 320then
287 logger "Switching to ${RUNLEVEL_BATTERY} runlevel" 321 logger "Switching to ${RUNLEVEL_BATTERY} runlevel"
288 /sbin/rc ${RUNLEVEL_BATTERY} 322 /sbin/rc ${RUNLEVEL_BATTERY}
289 fi 323fi
290} 324</pre>
325
326<p>
327Dont forget to run <c>chmod +x /etc/acpi/actions/pmg_switch_runlevel.sh</c> to
328make the script executable. The last thing that needs to be done is calling the
329script whenever the power source changes. That's done by catching ACPI events
330with the help of <c>acpid</c>. First you need to know which events are
331generated when the power source changes. The events are called
332<c>ac_adapter</c> and <c>battery</c> on most laptops, but it might be different
333on yours.
291</pre> 334</p>
335
336<pre caption="Determining ACPI events for changing the power source">
337# <i>tail -f /var/log/messages | grep "ACPI event"</i>
338</pre>
339
340<p>
341Run the command above and pull the power cable. You should see something like
342this:
343</p>
344
345<pre caption="Sample output for power source changes">
346[Tue Sep 20 17:39:06 2005] ACPI event "ac_adapter AC 00000080 00000000"
347[Tue Sep 20 17:39:06 2005] ACPI event "battery BAT0 00000080 00000001"
348</pre>
349
350<p>
351The interesting part is the quoted string after <c>ACPI event</c>. It will
352be matched by the event line in the files you are going to create below. Don't
353worry if your system generates multiple events or always the same. As long as
354any event is generated, runlevel changing will work.
355</p>
292 356
293<pre caption="/etc/acpi/events/pmg_ac_adapter"> 357<pre caption="/etc/acpi/events/pmg_ac_adapter">
358<comment># replace "ac_adapter" below with the event generated on your laptop</comment>
359<comment># For example, ac_adapter.* will match ac_adapter AC 00000080 00000000</comment>
294event=ac_adapter.* 360event=ac_adapter.*
295action=/etc/acpi/actions/pmg_ac_adapter.sh %e 361action=/etc/acpi/actions/pmg_switch_runlevel.sh %e
296</pre> 362</pre>
297 363
298<pre caption="/etc/acpi/events/pmg_battery"> 364<pre caption="/etc/acpi/events/pmg_battery">
365<comment># replace "battery" below with the event generated on your laptop</comment>
366<comment># For example, battery.* will match battery BAT0 00000080 00000001</comment>
299event=battery.* 367event=battery.*
300action=/etc/acpi/actions/pmg_battery.sh %e 368action=/etc/acpi/actions/pmg_switch_runlevel.sh %e
301</pre> 369</pre>
302 370
303<pre caption="/etc/acpi/actions/pmg_ac_adapter.sh">
304#!/bin/bash
305
306source /etc/acpi/switch_runlevel.sh
307SwitchRunlevel
308</pre>
309
310<pre caption="/etc/acpi/actions/pmg_battery.sh">
311#!/bin/bash
312
313source /etc/acpi/switch_runlevel.sh
314SwitchRunlevel
315</pre>
316
317<p> 371<p>
318Some of these files must be executable. Last not least restart acpid to have 372Finally acpid has to be restarted to recognize the changes.
319it recognize the changes.
320</p> 373</p>
321 374
322<pre caption="Finishing runlevel switching with acpid"> 375<pre caption="Finishing runlevel switching with acpid">
323<i># chmod +x /etc/acpi/switch_runlevel.sh</i>
324<i># chmod +x /etc/acpi/actions/pmg_*</i>
325<i># /etc/init.d/acpid restart</i> 376# <i>/etc/init.d/acpid restart</i>
326</pre> 377</pre>
327 378
328<p> 379<p>
329Give it a try: Plug AC in and out and watch syslog for the "Switching to AC 380Give it a try: Plug AC in and out and watch syslog for the "Switching to AC
330mode" or "Switching to battery mode" messages. See the Troubleshooting 381mode" or "Switching to battery mode" messages. See the <uri
331section if the script is not able to detect the power source correctly. 382link="#doc_chap8">Troubleshooting section</uri> if the script is not able to
383detect the power source correctly.
332</p> 384</p>
333 385
334<p> 386<p>
335Due to the nature of the event mechanism, your laptop will boot into runlevel 387Due to the nature of the event mechanism, your laptop will boot into runlevel
336<e>default</e> regardless of the AC/battery state. You can add another entry 388<c>default</c> regardless of the AC/battery state. This is fine when running
337to the boot loader with <c>softlevel=battery</c>, but it's likely to forget 389from AC, but we'd like to boot into the battery runlevel otherwise. One
338choosing it. A better way is faking an ACPI event in the end of the boot 390solution would be to add another entry to the boot loader with the parameter
339process and let the <path>/etc/acpi/default.sh</path> script decide whether a 391<c>softlevel=battery</c>, but it's likely to forget choosing it. A better way
392is faking an ACPI event in the end of the boot process and letting
393<path>pmg_switch_runlevel.sh</path> script decide whether a runlevel change is
340runlevel change is necessary. Open <path>/etc/conf.d/local.start</path> in your 394necessary. Open <path>/etc/conf.d/local.start</path> in your favourite editor
341favourite editor and add these lines: 395and add these lines:
342</p> 396</p>
343 397
344<pre caption="Runlevel switch at boot time by editing local.start"> 398<pre caption="Runlevel adjustment at boot time by editing local.start">
345<comment># Fake acpi event to switch runlevel if running on batteries</comment> 399<comment># Fake acpi event to switch runlevel if running on batteries</comment>
346/etc/acpi/actions/pmg_battery.sh "battery/battery" 400/etc/acpi/actions/pmg_switch_runlevel.sh "battery/battery"
347</pre> 401</pre>
348 402
349<p> 403<p>
350Prepared like this you can activate Power Management policies for individual 404Prepared like this you can activate Power Management policies for individual
351devices. 405devices.
352</p> 406</p>
353 407
354</body> 408</body>
355</section> 409</section>
356</chapter> 410</chapter>
357 411
358<chapter> 412<chapter>
359<title>CPU Power Management</title> 413<title>CPU Power Management</title>
360<section> 414<section>
415<body>
416
417<p>
418Mobile processors can operate at different frequencies. Some allow changing
419voltage as well. Most of the time your CPU doesn't need to run at full speed
420and scaling it down will save much energy - often without any performance
421decrease.
422</p>
423
424</body>
425</section>
426<section>
361<title>Some technical terms</title> 427<title>Some Technical Terms</title>
362<body> 428<body>
363 429
364<p> 430<p>
365CPU frequency scaling brings up some technical terms that might be unknown to 431CPU frequency scaling brings up some technical terms that might be unknown to
366you. Here's a quick introduction. 432you. Here's a quick introduction.
367</p> 433</p>
368 434
369<p> 435<p>
370First of all, the kernel has to be able to change the processor's frequency. The 436First of all, the kernel has to be able to change the processor's frequency.
371<e>CPUfreq processor driver</e> knows the commands to do it on your CPU. Thus 437The <b>CPUfreq processor driver</b> knows the commands to do it on your CPU.
372it's important to choose the right one in your kernel. You should already have 438Thus it's important to choose the right one in your kernel. You should already
373done it above. Once the kernel knows how to change frequencies, it has to know 439have done it above. Once the kernel knows how to change frequencies, it has to
374which frequency it should set. This is done according to the <e>policy</e> which 440know which frequency it should set. This is done according to the <b>policy</b>
375consists of <e>CPUfreq policy</e> and a <e>governor</e>. A CPUfreq policy are 441which consists of a <b>CPUfreq policy</b> and a <b>governor</b>. A CPUfreq
376just two numbers which define a range the frequency has to stay between - 442policy are just two numbers which define a range the frequency has to stay
377minimal and maximal frequency. The governor now decides which of the available 443between - minimal and maximal frequency. The governor now decides which of the
378frequencies in between minimal and maximal frequency to choose. For example, the 444available frequencies in between minimal and maximal frequency to choose. For
379<e>powersave governor</e> always chooses the lowest frequency available, the 445example, the <b>powersave governor</b> always chooses the lowest frequency
380<e>performance governor</e> the highest one. The <e>userspace governor</e> makes 446available, the <b>performance governor</b> the highest one. The <b>userspace
381no decision but chooses whatever the user (or a program in userspace) wants - 447governor</b> makes no decision but chooses whatever the user (or a program in
382which means it reads the frequency from 448userspace) wants - which means it reads the frequency from
383<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed</path>. 449<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed</path>.
384</p> 450</p>
385 451
386<p> 452<p>
387This doesn't sound like dynamic frequency changes yet and in fact it isn't. 453This doesn't sound like dynamic frequency changes yet and in fact it isn't.
388Dynamics however can be accomplished with various approaches. For example, 454Dynamics however can be accomplished with various approaches. For example, the
389the <e>ondemand governor</e> makes its decisions depending on the current CPU 455<b>ondemand governor</b> makes its decisions depending on the current CPU load.
390load. The same is done by various userland tools like <c>cpudyn</c>, 456The same is done by various userland tools like <c>cpudyn</c>, <c>cpufreqd</c>,
391<c>speedfreq</c>, <c>powernowd</c> and many more. ACPI events can be used to 457<c>powernowd</c> and many more. ACPI events can be used to enable or disable
392enable or disable dynamic frequency changes depending on power source. 458dynamic frequency changes depending on power source.
393</p> 459</p>
394 460
395</body> 461</body>
396</section>
397<section> 462</section>
463<section>
398<title>Setting the frequency manually</title> 464<title>Setting The Frequency</title>
399<body> 465<body>
400 466
401<p> 467<p>
402Decreasing CPU speed and voltage has two advantages: On the one hand less 468Decreasing CPU speed and voltage has two advantages: On the one hand less
403energy is consumed, on the other hand there is thermal improvement as your 469energy is consumed, on the other hand there is thermal improvement as your
406between performance loss and energy saving. 472between performance loss and energy saving.
407</p> 473</p>
408 474
409<note> 475<note>
410Not every laptop supports frequency scaling. If unsure, have a look at the list 476Not every laptop supports frequency scaling. If unsure, have a look at the list
411of supported processors in the <e>Troubleshooting</e> section to verify your's 477of supported processors in the <uri link="#doc_chap8">Troubleshooting</uri>
412is supported. 478section to verify yours is supported.
413</note> 479</note>
414 480
415<p> 481<p>
416It's time to test whether CPU frequency changing works. To get comfortable with 482It's time to test whether CPU frequency changing works. Let's install another
417the interface to the kernel, first do some manual speed modifications. To set 483tool: <c>sys-power/cpufrequtils</c>.
418another CPU speed, use:
419</p>
420
421<pre caption="Manual CPU speed modifications">
422<comment>(Get current frequency)</comment>
423# <i>grep "cpu MHz" /proc/cpuinfo</i>
424
425<comment>(Lists supported frequencies. This might fail.)</comment>
426# <i>cd /sys/devices/system/cpu/cpu0/cpufreq/</i>
427# <i>cat scaling_available_frequencies</i>
428
429<comment>(Change frequency to 1 GHz (1000000 KHz)
430Replace with a frequency your laptop supports.)</comment>
431# <i>echo -n userspace > scaling_governor</i>
432# <i>echo -n 1000000 > scaling_setspeed</i>
433
434<comment>(Verify frequency was changed)</comment>
435# <i>grep "cpu MHz" /proc/cpuinfo</i>
436</pre>
437
438<p> 484</p>
439If you are getting error messages, please refer to the <e>Troubleshooting</e> 485
440chapter in the end of this guide. 486<pre caption="Checking CPU frequency">
487# <i>emerge cpufrequtils</i>
488# <i>cpufreq-info</i>
489</pre>
490
441</p> 491<p>
442 492Here is an example output:
443<p> 493</p>
444You can also write to <path>scaling_max_freq</path> and 494
445<path>scaling_min_freq</path> to set boundaries the frequency should stay in 495<pre caption="Sample output from cpufreq-info">
446between. 496cpufrequtils 0.3: cpufreq-info (C) Dominik Brodowski 2004
497Report errors and bugs to linux@brodo.de, please.
498analyzing CPU 0:
499 driver: centrino
500 CPUs which need to switch frequency at the same time: 0
501 hardware limits: 600 MHz - 1.40 GHz
502 available frequency steps: 600 MHz, 800 MHz, 1000 MHz, 1.20 GHz, 1.40 GHz
503 available cpufreq governors: conservative, ondemand, powersave, userspace, performance
504 current policy: frequency should be within 924 MHz and 1.40 GHz.
505 The governor "performance" may decide which speed to use
506 within this range.
507 current CPU frequency is 1.40 GHz.
508</pre>
509
447</p> 510<p>
511Now play around with <c>cpufreq-set</c> to make sure frequency switching works.
512Run <c>cpufreq-set -g ondemand</c> for example to activate the ondemand
513governor and verify the change with <c>cpufreq-info</c>. If it doesn't work as
514expected, you might find help in the <uri link="#doc_chap8">Troubleshooting
515section</uri> in the end of this guide.
516</p>
448 517
449<note> 518<p>
450Some kernel seem to be buggy about updating <path>/proc/cpuinfo</path>. If you 519<c>cpufrequtils</c> can operate in an automatic mode (when you use the
451don't see any change there, this doesn't neccessarily mean the CPU frequency 520<b>ondemand</b> governor), you can also switch to the <b>userspace</b> governor
452wasn't changed. If this happens to you, run <c>emerge x86info</c>, update your 521if you want to manually set a specific speed. You can also statically set your
453kernel as asked and check the current frequency with <c>x86info -mhz</c>. 522CPU to its highest or lowest frequency by using the <b>performance</b>
454</note> 523and <b>powersave</b> governors, respectively.
524</p>
455 525
526<pre caption="Changing CPU speeds">
527<comment>(Set the highest available frequency)</comment>
528# <i>cpufreq-set -g performance</i>
529<comment>(Set the lowest available frequency)</comment>
530# <i>cpufreq-set -g powersave</i>
531<comment>(Set a specific frequency)</comment>
532# <i>cpufreq-set -g userspace</i>
533# <i>cpufreq-set -f 2.00ghz</i>
534</pre>
535
456</body> 536</body>
457</section>
458<section> 537</section>
459<title>Automated frequency adaption</title> 538<section>
539<title>Other CPU Speed Utilities</title>
460<body> 540<body>
461 541
462<p> 542<p>
463The above is quite nice, but not doable in daily life. Better let your system 543While <c>cpufrequtils</c> may be the best all-around program, there are some
464set the appropriate frequency automatically. There are many different approaches 544other choices available in Portage. The following table gives a quick overview
465to do this. The following table gives a quick overview to help you decide on one 545of available CPU speed utilities. It's roughly separated in three categories
466of them. It's roughly seperated in three categories <e>kernel</e> for approaches 546<b>kernel</b> for approaches that only need kernel support, <b>daemon</b> for
467that only need kernel support, <e>daemon</e> for programs that run in the 547programs that run in the background and <b>graphical</b> for programs that
468background and <e>graphical</e> for programs that provide a GUI for easy 548provide a GUI for easy configuration and changes.
469configuration and changes.
470</p> 549</p>
471 550
472<table> 551<table>
473<tr> 552<tr>
474 <th>Name</th> 553 <th>Name</th>
483 <ti>Kernel</ti> 562 <ti>Kernel</ti>
484 <ti>CPU load</ti> 563 <ti>CPU load</ti>
485 <ti>N.A.</ti> 564 <ti>N.A.</ti>
486 <ti>N.A.</ti> 565 <ti>N.A.</ti>
487 <ti> 566 <ti>
567 Chooses maximal frequency on CPU load and slowly steps down when the CPU is
568 idle. Further tuning through files in
569 <path>/sys/devices/system/cpu/cpu0/cpufreq/ondemand/</path>. Still requires
570 userland tools (programs, scripts) if governor switching or similar is
571 desired.
572 </ti>
573</tr>
574<tr>
575 <ti>'conservative' governor</ti>
576 <ti>Kernel</ti>
577 <ti>CPU load</ti>
578 <ti>N.A.</ti>
579 <ti>N.A.</ti>
580 <ti>
581 Unlike the ondemand governor, conversative doesn't jump to maximum
582 frequency when CPU load is high, but increases the frequency step by step.
488 Further tuning through files in 583 Further tuning through files in
489 <path>/sys/devices/system/cpu/cpu0/cpufreq/ondemand/</path>. Still requires 584 <path>/sys/devices/system/cpu/cpu0/cpufreq/ondemand/</path>. Still requires
490 userland tools (programs, scripts) if governor switching or similar is 585 userland tools (programs, scripts) if governor switching or similar is
491 desired. 586 desired.
492 </ti> 587 </ti>
493</tr> 588</tr>
494<tr> 589<tr>
495 <ti><uri link="http://mnm.uib.es/~gallir/cpudyn/">cpudyn</uri></ti> 590 <ti><uri link="http://mnm.uib.es/~gallir/cpudyn/">cpudyn</uri></ti>
496 <ti>Daemon</ti> 591 <ti>Daemon</ti>
497 <ti>CPU load</ti> 592 <ti>CPU load</ti>
498 <ti>None</ti> 593 <ti>Performance, powersave</ti>
499 <ti>Dynamic</ti> 594 <ti>Dynamic</ti>
500 <ti> 595 <ti>
501 Also supports disk standby - notice however that <e>laptop mode</e> in most 596 Also supports disk standby - notice however that <e>laptop mode</e> in most
502 cases will do a better job. 597 cases will do a better job.
503 </ti> 598 </ti>
504</tr> 599</tr>
505<tr> 600<tr>
506 <ti><uri link="http://sourceforge.net/projects/cpufreqd/">cpufreqd</uri></ti> 601 <ti><uri link="http://sourceforge.net/projects/cpufreqd/">cpufreqd</uri></ti>
507 <ti>Daemon</ti> 602 <ti>Daemon</ti>
508 <ti>Battery state, CPU load, running programs</ti> 603 <ti>Battery state, CPU load, temperature, running programs and more</ti>
509 <ti>All available</ti> 604 <ti>All available</ti>
510 <ti>None</ti> 605 <ti>None</ti>
511 <ti> 606 <ti>
512 Sophisticated (but also complicated) setup. An optimal configuration 607 Sophisticated (but somewhat complicated) setup. Extendible through plugins
513 requires detailed knowledge of your system. 608 like sensor monitoring (lm_sensors) or coordinating some NVidia based
609 graphics card memory and core. Cpufreqd is SMP aware and can optionally be
610 controlled manually at runtime.
514 </ti> 611 </ti>
515</tr> 612</tr>
516<tr> 613<tr>
517 <ti> 614 <ti>
518 <uri link="http://www.deater.net/john/powernowd.html">powernowd</uri> 615 <uri link="http://www.deater.net/john/powernowd.html">powernowd</uri>
524 <ti> 621 <ti>
525 Supports SMP. 622 Supports SMP.
526 </ti> 623 </ti>
527</tr> 624</tr>
528<tr> 625<tr>
626 <ti>
627 <uri
628 link="http://projects.simpledesigns.com.pl/project/ncpufreqd/">ncpufreqd</uri>
629 </ti>
630 <ti>Daemon</ti>
631 <ti>Temperature</ti>
632 <ti>None</ti>
633 <ti>Powersave, performance</ti>
634 <ti>
635 Toggles the used governor between performance and powersave depending on
636 system temperature. Very useful on laptops with notorious heat problems.
637 </ti>
638</tr>
639<tr>
529 <ti><uri link="http://www.goop.org/~jeremy/speedfreq/">speedfreq</uri></ti> 640 <ti><uri link="http://www.goop.org/~jeremy/speedfreq/">speedfreq</uri></ti>
530 <ti>Daemon</ti> 641 <ti>Daemon</ti>
531 <ti>CPU load</ti> 642 <ti>CPU load</ti>
532 <ti>None</ti> 643 <ti>None</ti>
533 <ti>Dynamic, powersave, performance, fixed speed</ti> 644 <ti>Dynamic, powersave, performance, fixed speed</ti>
534 <ti> 645 <ti>
535 Small yet powerful with an useful client/server interface. Requires a 2.6 646 Easy to configure with a nice client/server interface. Requires a 2.6
536 kernel. 647 kernel. Unmaintained, broken and thus removed from Portage. Please switch
648 to cpufreqd if you're still using it.
537 </ti> 649 </ti>
538</tr> 650</tr>
539<tr> 651<tr>
540 <ti><uri link="http://cpuspeedy.sourceforge.net/">gtk-cpuspeedy</uri></ti> 652 <ti><uri link="http://cpuspeedy.sourceforge.net/">gtk-cpuspeedy</uri></ti>
541 <ti>Graphical</ti> 653 <ti>Graphical</ti>
542 <ti>None</ti> 654 <ti>None</ti>
543 <ti>None</ti> 655 <ti>None</ti>
544 <ti>None</ti> 656 <ti>None</ti>
545 <ti> 657 <ti>
546 Gnome application, a graphical tool to set CPU frequency manually. It does 658 Gnome application, a graphical tool to set CPU frequency manually. It does
547 not offer any automation and is mainly listed for the sake of completeness. 659 not offer any automation.
548 </ti> 660 </ti>
549</tr> 661</tr>
550<tr> 662<tr>
551 <ti>klaptopdaemon</ti> 663 <ti>klaptopdaemon</ti>
552 <ti>Graphical</ti> 664 <ti>Graphical</ti>
558 </ti> 670 </ti>
559</tr> 671</tr>
560</table> 672</table>
561 673
562<p> 674<p>
563While adjusting the frequency to the current load looks simple on the first 675While adjusting the frequency to the current load looks simple at a first
564view, it's not such a trivial task. A bad algorithm can cause switching between 676glance, it's not such a trivial task. A bad algorithm can cause switching
565two frequencies all the time or wasting energy when setting frequency to an 677between two frequencies all the time or wasting energy when setting frequency
566unnecessary high level. 678to an unnecessary high level.
567</p>
568
569<p> 679</p>
680
681<p>
570Which one to choose? If you have no idea about it, first try <c>speedfreq</c>: 682Which one to choose? If you have no idea about it, try <c>cpufreqd</c>:
571</p> 683</p>
572 684
573<pre caption="Installing speedfreq"> 685<pre caption="Installing cpufreqd">
574# <i>emerge speedfreq</i> 686# <i>emerge cpufreqd</i>
575# <i>rc-update add speedfreq battery</i>
576</pre> 687</pre>
577 688
578<p>
579<c>speedfreq</c> can be configured by editing
580<path>/etc/conf.d/speedfreq</path>. For example, if you like users to be able
581to change the policy, modify <c>SPEEDFREQ_OPTS=""</c> to
582<c>SPEEDFREQ_OPTS="-u"</c>. Having done your changes, start the daemon.
583</p> 689<p>
690<c>cpufreqd</c> can be configured by editing <path>/etc/cpufreqd.conf</path>.
691The default one that ships with cpufreqd may look a bit confusing. I recommend
692replacing it with the one from former Gentoo developer Henrik Brix Andersen
693(see below). Please notice that you need cpufreqd-2.0.0 or later. Earlier
694versions have a different syntax for the config file.
695</p>
584 696
697<pre caption="/etc/cpufreqd.conf (cpufreqd-2.0.0 and later)">
698[General]
699pidfile=/var/run/cpufreqd.pid
700poll_interval=3
701enable_plugins=acpi_ac, acpi_battery
702enable_remote=1
703remote_group=wheel
704verbosity=5
705[/General]
706
707[Profile]
708name=ondemand
709minfreq=0%
710maxfreq=100%
711policy=ondemand
712[/Profile]
713
714[Profile]
715name=conservative
716minfreq=0%
717maxfreq=100%
718policy=conservative
719[/Profile]
720
721[Profile]
722name=powersave
723minfreq=0%
724maxfreq=100%
725policy=powersave
726[/Profile]
727
728[Profile]
729name=performance
730minfreq=0%
731maxfreq=100%
732policy=performance
733[/Profile]
734
735[Rule]
736name=battery
737ac=off
738profile=conservative
739[/Rule]
740
741[Rule]
742name=battery_low
743ac=off
744battery_interval=0-10
745profile=powersave
746[/Rule]
747
748[Rule]
749name=ac
750ac=on
751profile=ondemand
752[/Rule]
753</pre>
754
755<p>
756Now you can start the cpufreqd daemon. Add it to the <c>default</c> and
757<c>battery</c> runlevel as well.
758</p>
759
585<pre caption="Starting speedfreq"> 760<pre caption="Starting cpufreqd">
761# <i>rc-update add cpufreqd default battery</i>
586# <i>/etc/init.d/speedfreq start</i> 762# <i>/etc/init.d/cpufreqd start</i>
587</pre> 763</pre>
588 764
589<p> 765<p>
590Setting up cpufreqd is a little bit more complicated. 766Sometimes it can be desirable to select another policy than the daemon chooses,
767for example when battery power is low, but you know that AC will be available
768soon. In that case you can turn on cpufreqd's manual mode with <c>cpufreqd-set
769manual</c> and select one of your configured policies (as listed by
770<c>cpufreqd-get</c>). You can leave manual mode by executing <c>cpufreqd-set
771dynamic</c>.
591</p> 772</p>
592 773
593<warn> 774<warn>
594Do not run more than one of the above programs at the same time. It may cause 775Do not run more than one of the above programs at the same time. It may cause
595confusion like switching between two frequencies all the time. If you just 776confusion like switching between two frequencies all the time.
596installed speedfreq, skip cpufreqd now.
597</warn> 777</warn>
598 778
599<pre caption="Installing cpufreqd">
600# <i>emerge cpufreqd</i>
601# <i>rc-update add cpufreqd battery</i>
602</pre>
603
604<p>
605<c>cpufreqd</c> comes with a default configuration in
606<path>/etc/cpufreqd.conf</path>.
607Change the config file to fit your needs. The following will save more energy
608than the default one - at the cost of less performance, of course.
609</p>
610
611<pre caption="A sample cpufreqd config file">
612[General]
613pidfile=/var/run/cpufreqd.pid
614poll_interval=2
615pm_type=acpi
616<comment># Uncomment the following line to enable ACPI workaround (see cpufreqd.conf(5))
617# acpi_workaround=1</comment>
618verbosity=4 <comment>#(if you want a minimal logging set to 5)</comment>
619
620<comment># Full performance</comment>
621[Profile]
622name=ac
623minfreq=600000
624maxfreq=1400000
625policy=performance
626
627<comment># Maximum power saving</comment>
628[Profile]
629name=battery
630minfreq=600000
631maxfreq=900000
632policy=powersave
633
634<comment># Constant frequency</comment>
635[Profile]
636name=dvd
637minfreq=900000
638maxfreq=1100000
639policy=powersave
640
641<comment># Full performance when running on AC</comment>
642[Rule]
643name=ac_on
644ac=on
645profile=ac
646
647<comment># Compiling should be fast if battery state is ok</comment>
648[Rule]
649name=compiling
650ac=off
651battery_interval=30-100
652programs=emerge,make,gcc,cpp
653cpu_interval=0-100
654profile=ac
655
656<comment># watching DVD's gets sluggish with slow CPU frequency
657# Can also be used for games etc.</comment>
658[Rule]
659name=dvd_watching
660ac=off
661battery_interval=15-100
662programs=xine,mplayer,avidemux,kaffeine,kmplayer
663cpu_interval=0-100
664profile=dvd
665
666<comment># If above doesn't apply, maximise power saving</comment>
667[Rule]
668name=battery_on
669ac=off
670battery_interval=0-100
671cpu_interval=0-100
672profile=battery
673</pre>
674
675<p>
676<c>cpudyn</c> and <c>powernowd</c> are installed in the same way as
677<c>speedfreq</c>.
678</p>
679
680</body> 779</body>
681</section> 780</section>
682
683<section> 781<section>
684<title>Verifying the result</title> 782<title>Verifying the result</title>
685
686<body> 783<body>
687 784
688<p> 785<p>
689The last thing to check is that your new policies do a good job. An easy way to 786The last thing to check is that your new policies do a good job. An easy way to
690do so is monitoring CPU speed while working with your laptop: 787do so is monitoring CPU speed while working with your laptop:
691</p> 788</p>
692 789
693<pre caption="Monitoring CPU speed"> 790<pre caption="Monitoring CPU speed">
694# <i>watch -n 1 grep "cpu MHz" /proc/cpuinfo</i> 791# <i>watch grep \"cpu MHz\" /proc/cpuinfo</i>
695</pre> 792</pre>
696 793
697<p> 794<p>
698If <path>/proc/cpuinfo</path> doesn't get updated (see above), monitor the CPU 795If <path>/proc/cpuinfo</path> doesn't get updated (see <uri
699frequency with: 796link="#doc_chap8">Troubleshooting</uri>), monitor the CPU frequency with
797<c>sys-apps/x86info</c>:
700</p> 798</p>
701 799
702<pre caption="Alternative CPU speed monitoring"> 800<pre caption="Alternative CPU speed monitoring">
703# <i>watch -n 1 x86info -mhz</i> 801# <i>watch x86info -mhz</i>
704</pre> 802</pre>
705 803
706<p> 804<p>
707Depending on your setup, CPU speed should increase on heavy load, decrease on 805Depending on your setup, CPU speed should increase on heavy load, decrease on
708no activity or just stay at the same level. 806no activity or just stay at the same level. When using <c>cpufreqd</c> and
807verbosity set to 5 or higher in <path>cpufreqd.conf</path> you'll get
808additional information about what's happening reported to <c>syslog</c>.
709</p> 809</p>
710 810
711</body> 811</body>
712</section> 812</section>
713</chapter> 813</chapter>
714 814
715<chapter> 815<chapter>
716<title>LCD Power Management</title> 816<title>LCD Power Management</title>
717<section> 817<section>
718<title>Energy consumer no. 1</title>
719<body> 818<body>
720 819
721<p> 820<p>
722As you can see in <uri link="#doc_chap1_fig1">figure 1.1</uri>, the LCD display 821As you can see in <uri link="#doc_chap1_fig1">figure 1.1</uri>, the LCD
723consumes the biggest part of energy (might not be the case for non-mobile 822display consumes the biggest part of energy (might not be the case for
724CPU's). Thus it's quite important not only to shut the display off when not 823non-mobile CPU's). Thus it's quite important not only to shut the display off
725needed, but also to reduce it's backlight if possible. Most laptops offer the 824when not needed, but also to reduce it's backlight if possible. Most laptops
726possibility to control the backlight dimming. 825offer the possibility to control the backlight dimming.
727</p>
728
729<p> 826</p>
827
828</body>
829</section>
830<section>
831<title>Standby settings</title>
832<body>
833
834<p>
730First thing to check is the standby/suspend/off timings of the display. As this 835The first thing to check is the standby/suspend/off timings of the display. As
731depends heavily on your windowmanager, I'll let you figure it out yourself. 836this depends heavily on your windowmanager, I'll let you figure it out
732Just two common places: Blanking the terminal can be done with <c>setterm 837yourself. Just two common places: Blanking the terminal can be done with
733-blank &lt;number-of-minutesM&gt;</c>, <c>setterm -powersave on</c> and 838<c>setterm -blank &lt;number-of-minutesM&gt;</c>, <c>setterm -powersave on</c>
734<c>setterm -powerdown &lt;number-of-minutesM&gt;</c>. 839and <c>setterm -powerdown &lt;number-of-minutesM&gt;</c>. For X.org, modify
735For Xorg, modify <path>/etc/X11/xorg.conf</path> similar to this: 840<path>/etc/X11/xorg.conf</path> similar to this:
736</p> 841</p>
737 842
738<pre caption="LCD suspend settings in Xorg and XFree86"> 843<pre caption="LCD suspend settings in X.org">
739Section "ServerLayout" 844Section "ServerFlags"
740 Identifier [...]
741 [...]
742 Option "BlankTime" "5" <comment># Blank the screen after 5 minutes (Fake)</comment> 845 Option "blank time" "5" <comment># Blank the screen after 5 minutes (Fake)</comment>
743 Option "StandbyTime" "10" <comment># Turn off screen after 10 minutes (DPMS)</comment> 846 Option "standby time" "10" <comment># Turn off screen after 10 minutes (DPMS)</comment>
744 Option "SuspendTime" "20" <comment># Full suspend after 20 minutes</comment> 847 Option "suspend time" "20" <comment># Full suspend after 20 minutes</comment>
745 Option "OffTime" "30" <comment># Turn off after half an hour</comment> 848 Option "off time" "30" <comment># Turn off after half an hour</comment>
746 [...] 849 [...]
747EndSection 850EndSection
748 851
749[...] 852[...]
750 853
751Section "Monitor" 854Section "Monitor"
752 Identifier [...] 855 Identifier [...]
753 Option "DPMS" "true" 856 Option "DPMS"
754 [...] 857 [...]
755EndSection 858EndSection
756</pre> 859</pre>
757 860
758<p> 861</body>
759This is the same for XFree86 and <path>/etc/X11/XF86Config</path>. 862</section>
760</p> 863<section>
864<title>Backlight dimming</title>
865<body>
761 866
762<p> 867<p>
763Probably more important is the backlight dimming. If you have access to the 868Probably more important is the backlight dimming. If you have access to the
764dimming settings via a tool, write a small script that dims the backlight in 869dimming settings via a tool, write a small script that dims the backlight in
765battery mode and place it in your <e>battery</e> runlevel. 870battery mode and place it in your <c>battery</c> runlevel. The following script
871should work on most IBM Thinkpads and Toshiba laptops. You've got to enable the
872appropriate option in your kernel (IBM Thinkpads only). For Toshiba laptops,
873install <c>sys-power/acpitool</c> and skip configuration of <c>thinkpad_acpi</c>
874(formerly called <c>ibm_acpi</c>) as described below.
875</p>
876
877<warn>
878Support for setting brightness is marked experimental in thinkpad_acpi. It
879accesses hardware directly and may cause severe harm to your system. Please
880read the <uri link="http://ibm-acpi.sourceforge.net/">thinkpad_acpi
881website</uri>
882</warn>
883
766</p> 884<p>
885To be able to set the brightness level, the thinkpad_acpi module has to be
886loaded with the experimental parameter.
887</p>
888
889<pre caption="automatically loading the thinkpad_acpi module">
890<comment>(Please read the warnings above before doing this!)</comment>
891# <i>echo "options thinkpad_acpi experimental=1" >> /etc/modprobe.d/thinkpad_acpi</i>
892# <i>update-modules</i>
893# <i>echo thinkpad_acpi >> /etc/modules.autoload.d/kernel-2.6</i>
894# <i>modprobe thinkpad_acpi</i>
895</pre>
896
897<p>
898This should work without error messages and a file
899<path>/proc/acpi/ibm/brightness</path> should be created after loading the
900module. An init script will take care of choosing the brightness according to
901the power source.
902</p>
903
904<pre caption="/etc/conf.d/lcd-brightness">
905<comment># See /proc/acpi/ibm/brightness for available values</comment>
906<comment># Please read /usr/src/linux/Documentation/thinkpad-acpi.txt</comment>
907
908<comment># brightness level in ac mode. Default is 7.</comment>
909BRIGHTNESS_AC=7
910
911<comment># brightness level in battery mode. Default is 4.</comment>
912BRIGHTNESS_BATTERY=4
913</pre>
914
915<pre caption="/etc/init.d/lcd-brightness">
916#!/sbin/runscript
917
918set_brightness() {
919 if on_ac_power
920 then
921 LEVEL=${BRIGHTNESS_AC:-7}
922 else
923 LEVEL=${BRIGHTNESS_BATTERY:-4}
924 fi
925
926 if [ -f /proc/acpi/ibm/brightness ]
927 then
928 ebegin "Setting LCD brightness"
929 echo "level ${LEVEL}" > /proc/acpi/ibm/brightness
930 eend $?
931 elif [[ -e /usr/bin/acpitool &amp;&amp; -n $(acpitool -T | grep "LCD brightness") ]]
932 then
933 ebegin "Setting LCD brightness"
934 acpitool -l $LEVEL >/dev/null || ewarn "Unable to set lcd brightness"
935 eend $?
936 else
937 ewarn "Setting LCD brightness is not supported."
938 ewarn "For IBM Thinkpads, check that thinkpad_acpi is loaded into the kernel"
939 ewarn "For Toshiba laptops, you've got to install sys-power/acpitool"
940 fi
941}
942
943start() {
944 set_brightness
945}
946
947stop () {
948 set_brightness
949}
950</pre>
951
952<p>
953When done, make sure brightness is adjusted automatically by adding it to the
954battery runlevel.
955</p>
956
957<pre caption="Enabling automatic brightness adjustment">
958# <i>chmod +x /etc/init.d/lcd-brightness</i>
959# <i>rc-update add lcd-brightness battery</i>
960# <i>rc</i>
961</pre>
767 962
768</body> 963</body>
769</section> 964</section>
770</chapter> 965</chapter>
771 966
772<chapter> 967<chapter>
773<title>Disk Power Management</title> 968<title>Disk Power Management</title>
774<section> 969<section>
775<title>Sleep when idle</title> 970<body>
971
972<p>
973Hard disks consume less energy in sleep mode. Therefore it makes sense to
974activate power saving features whenever the hard disk is not used for a certain
975amount of time. I'll show you two alternative possibilities to do it. First,
976laptop-mode will save most energy due to several measures which prevent or at
977least delay write accesses. The drawback is that due to the delayed write
978accesses a power outage or kernel crash will be more dangerous for data loss.
979If you don't like this, you have to make sure that there are no processes which
980write to your hard disk frequently. Afterwards you can enable power saving
981features of your hard disk with <c>hdparm</c> as the second alternative.
982</p>
983
776<body> 984</body>
985</section>
986<section>
987<title>Increasing idle time - laptop-mode</title>
988<body>
777 989
778<p>
779Let's bring the hard disk to sleep as early as possible whenever it is not
780needed. I'll show you two possibilities to do it. First <c>cpudyn</c> supports
781Disk Power Management. Uncomment the lines in the "Disk Options" section in
782<path>/etc/conf.d/cpudyn</path>. To put your first disk to sleep after 60
783seconds of no activity, you would modify it like this:
784</p> 990<p>
785 991Recent 2.6 kernels include the so-called <c>laptop-mode</c>. When activated,
786<pre caption="Using cpudyn for disk standby"> 992dirty buffers are written to disk on read calls or after 10 minutes (instead of
787<comment>################################################ 99330 seconds). This minimizes the time the hard disk needs to be spun up.
788# DISK OPTIONS
789# (disabled by default)
790################################################
791
792#
793# Timeout to put the disk in standby mode if there was no
794# io during that period (in seconds)
795#
796</comment>
797TIMEOUT=60
798<comment>
799#
800# Specified disks to spindown (comma separated devices)
801#
802</comment>
803DISKS=/dev/hda
804</pre>
805
806<p> 994</p>
807The second possibility is using a small script and hdparm. Create 995
808<path>/etc/init.d/pm.hda</path> like this: 996<pre caption="Automated start of laptop-mode">
997# <i>emerge laptop-mode-tools</i>
998</pre>
999
809</p> 1000<p>
1001<c>laptop-mode-tools</c> has its configuration file in
1002<path>/etc/laptop-mode/laptop-mode.conf</path>. Adjust it the way you like it,
1003it's well commented. Run <c>rc-update add laptop_mode battery</c> to start it
1004automatically.
1005</p>
810 1006
1007<p>
1008Recent versions (1.11 and later) of laptop-mode-tools include a new tool
1009<c>lm-profiler</c>. It will monitor your system's disk usage and running
1010network services and suggests to disable unneeded ones. You can either disable
1011them through laptop-mode-tools builtin runlevel support (which will be reverted
1012by Gentoo's <c>/sbin/rc</c>) or use your <c>default</c>/<c>battery</c>
1013runlevels (recommended).
1014</p>
1015
1016<pre caption="Sample output from running lm-profiler">
1017# <i>lm-profiler</i>
1018Profiling session started.
1019Time remaining: 600 seconds
1020[4296896.602000] amarokapp
1021Time remaining: 599 seconds
1022[4296897.714000] sort
1023[4296897.970000] mv
1024Time remaining: 598 seconds
1025Time remaining: 597 seconds
1026[4296900.482000] reiserfs/0
1027</pre>
1028
1029<p>
1030After profiling your system for ten minutes, lm-profiler will present a list of
1031services which might have caused disk accesses during that time.
1032</p>
1033
1034<pre caption="lm-profiler suggests to disable some services">
1035Program: "atd"
1036Reason: standard recommendation (program may not be running)
1037Init script: /etc/init.d/atd (GUESSED)
1038
1039Do you want to disable this service in battery mode? [y/N]: <i>n</i>
1040</pre>
1041
1042<p>
1043To disable atd as suggested in the example above, you would run <c>rc-update
1044del atd battery</c>. Be careful not to disable services that are needed for
1045your system to run properly - <c>lm-profiler</c> is likely to generate some
1046false positives. Do not disable a service if you are unsure whether it's
1047needed.
1048</p>
1049
1050</body>
1051</section>
1052<section>
1053<title>Limiting Write Accesses</title>
1054<body>
1055
1056<p>
1057If you don't want to use laptop-mode, you must take special care to disable
1058services that write to your disk frequently - <c>syslogd</c> is a good
1059candidate, for example. You probably don't want to shut it down completely, but
1060it's possible to modify the config file so that "unnecessary" things don't get
1061logged and thus don't create disk traffic. <c>Cups</c> writes to disk
1062periodically, so consider shutting it down and only enable it manually when
1063needed.
1064</p>
1065
1066<pre caption="Disabling cups in battery mode">
1067# <i>rc-update del cupsd battery</i>
1068</pre>
1069
1070<p>
1071You can also use <c>lm-profiler</c> from laptop-mode-tools (see above) to find
1072services to disable. Once you eliminated all of them, go on with configuring
1073hdparm.
1074</p>
1075
1076</body>
1077</section>
1078<section>
1079<title>hdparm</title>
1080<body>
1081
1082<p>
1083The second possibility is using <c>hdparm</c>. Skip this if
1084you are using laptop-mode. Otherwise, edit <path>/etc/conf.d/hdparm</path> and
1085add the following values to your drive entries. This example assumes your hard
1086drive is called <b>hda</b>:
1087</p>
1088
811<pre caption="Using hdparm for disk standby"> 1089<pre caption="Using /etc/conf.d/hdparm for disk standby">
812#!/sbin/runscript 1090hda_args="-q -S12"
813start() {
814 ebegin "Activating Power Management for Hard Drives"
815 hdparm -q -S12 /dev/hda
816 eend $?
817}
818
819stop () {
820 ebegin "Deactivating Power Management for Hard Drives"
821 hdparm -q -S253 /dev/hda
822 eend $?
823}
824</pre> 1091</pre>
825 1092
1093<p>
1094This will activate power management for your hard drive. If you ever want to
1095deactivate power management, you can edit <path>/etc/conf.d/hdparm</path> and
1096change the values to <c>-q -S0</c>, or just run <c>hdparm -q -S0 /dev/hda</c>.
826<p> 1097</p>
827See <c>man hdparm</c> for the options. If your script is ready, add it to the 1098
828battery runlevel. 1099<p>
1100See <c>man hdparm</c> for the options. Though you can always start <c>hdparm</c>
1101manually when you are on battery power by running <c>/etc/init.d/hdparm
1102start</c>, it's much easier to automate its startup and shutdown. To do so, add
1103<c>hdparm</c> to the battery runlevel so that it will automatically enable power
1104management.
829</p> 1105</p>
830 1106
831<pre caption="Automate disk standby settings"> 1107<pre caption="Automate disk standby settings">
832# <i>chmod +x /etc/init.d/pm.hda</i>
833# <i>/sbin/depscan.sh</i>
834# <i>rc-update add pm.hda battery</i> 1108# <i>rc-update add hdparm battery</i>
835</pre> 1109</pre>
836 1110
837<impo> 1111<impo>
838Be careful with sleep/spin down settings of your hard drive. Setting it to 1112Be careful with sleep/spin down settings of your hard drive. Setting it to
839small values might wear out your drive and lose warranty. 1113small values might wear out your drive and lose warranty.
840</impo> 1114</impo>
841 1115
842</body> 1116</body>
843</section> 1117</section>
844<section> 1118<section>
845<title>Increasing idle time - laptop-mode</title>
846<body>
847
848<p>
849Recent kernels (2.6.6 and greater, recent 2.4 ones and others with patches)
850include the so-called <e>laptop-mode</e>. When activated, dirty buffers are
851written to disk on read calls or after 10 minutes (instead of 30 seconds). This
852minimizes the time the hard disk needs to be spun up.
853</p>
854
855<p>
856<!-- TODO: bug #45593 -->
857Besides kernel support you also need a script that controls starting and
858stopping of laptop-mode. You kernel documentation in
859<path>/usr/src/linux/Documentation/laptop-mode.txt</path> contains one as well
860as the package <c>laptop-mode-tools</c>. None of them is easy to install
861though.
862</p>
863
864<p>
865Ebuilds for laptop-mode-tools are not in Portage, because Gentoo developers
866don't think they are production ready yet. Take that into consideration
867before using the ebuilds which can be found in <uri
868link="http://bugs.gentoo.org/show_bug.cgi?id=45593">Bugzilla</uri>. The Gentoo
869Handbook tells you how to use external ebuilds if you don't know where to put
870them. Once your PORTDIR_OVERLAY contains the ebuilds, install the
871script:
872</p>
873
874<warn>
875This package is not seen as production ready and installing custom ebuilds from
876Bugzilla is not recommended. Please don't use laptop-mode-tools if you're
877unsure.
878</warn>
879
880<pre caption="Automated start of laptop-mode">
881# <i>emerge laptop-mode-tools</i>
882</pre>
883
884<p>
885<c>laptop-mode-tools</c> has it's configuration file in
886<path>/etc/laptop-mode/laptop-mode.conf</path>. Adjust it the way you like it,
887it's well commented. If you have <e>apm</e> or <e>acpi</e> in your USE flags,
888laptop-mode will be started automatically in battery mode. Otherwise you can
889automate it by running <c>rc-update add laptop-mode battery</c>.
890</p>
891
892</body>
893</section>
894<section>
895<title>Other tricks</title> 1119<title>Other tricks</title>
896<body> 1120<body>
897
898<p>
899Besides putting your disk to sleep state as early as possible, it is a good
900idea to minimize disk accesses. Have a look at processes that write to your
901disk frequently - the syslogd is a good candidate. You probably don't want to
902shut it down completely, but it's possible to modify the config file so that
903"unnecessary" things don't get logged and thus don't create disk traffic. Cups
904writes to disk periodically, so consider shutting it down and only enable it
905manually when needed.
906</p>
907
908<pre caption="Disabling cups in battery mode">
909# <i>rc-update del cupsd battery</i>
910</pre>
911 1121
912<p> 1122<p>
913Another possibility is to deactivate swap in battery mode. Before writing a 1123Another possibility is to deactivate swap in battery mode. Before writing a
914swapon/swapoff switcher, make sure there is enough RAM and swap isn't used 1124swapon/swapoff switcher, make sure there is enough RAM and swap isn't used
915heavily, otherwise you'll be in big problems. 1125heavily, otherwise you'll be in big problems.
916</p> 1126</p>
917 1127
918<p> 1128<p>
919If you don't want to use laptop-mode, it's still possible to minimize disk 1129If you don't want to use laptop-mode, it's still possible to minimize disk
920access by mounting certain directories as <e>tmpfs</e> - write accesses are not 1130access by mounting certain directories as <c>tmpfs</c> - write accesses are not
921stored on a disk, but in main memory and get lost with unmounting. Often it's 1131stored on a disk, but in main memory and get lost with unmounting. Often it's
922useful to mount <path>/tmp</path> like this - you don't have to pay special 1132useful to mount <path>/tmp</path> like this - you don't have to pay special
923attention as it gets cleared on every reboot regardless whether it was mounted 1133attention as it gets cleared on every reboot regardless whether it was mounted
924on disk or in RAM. Just make sure you have enough RAM and no program (like a 1134on disk or in RAM. Just make sure you have enough RAM and no program (like a
925download client or compress utility) needs extraordinary much space in 1135download client or compress utility) needs extraordinary much space in
931none /tmp tmpfs size=32m 0 0 1141none /tmp tmpfs size=32m 0 0
932</pre> 1142</pre>
933 1143
934<warn> 1144<warn>
935Pay attention to the size parameter and modify it for your system. If you're 1145Pay attention to the size parameter and modify it for your system. If you're
936unsure, don't try this at all, it can become a perfomance bottleneck easily. In 1146unsure, don't try this at all, it can become a performance bottleneck easily. In
937case you want to mount <path>/var/log</path> like this, make sure to merge the 1147case you want to mount <path>/var/log</path> like this, make sure to merge the
938log files to disk before unmounting. They are essential. Don't attempt to mount 1148log files to disk before unmounting. They are essential. Don't attempt to mount
939/var/tmp like this. Portage uses it for compiling... 1149<path>/var/tmp</path> like this. Portage uses it for compiling...
940</warn> 1150</warn>
941 1151
942</body> 1152</body>
943</section> 1153</section>
944</chapter> 1154</chapter>
945 1155
946<chapter> 1156<chapter>
947<title>Power Management for other devices</title> 1157<title>Power Management For Other Devices</title>
1158<section>
1159<title>Graphics Cards</title>
1160<body>
1161
1162<p>
1163In case you own an ATI graphics card supporting PowerPlay (dynamic clock
1164scaling for the graphics processing unit GPU), you can activate this
1165feature in X.org. Open <path>/etc/X11/xorg.conf</path> and add (or enable) the
1166<c>DynamicClocks</c> option in the Device section. Please notice that this
1167feature will lead to crashes on some systems.
1168</p>
1169
1170<pre caption="Enabling ATI PowerPlay support in X.org">
1171Section "Device"
1172[...]
1173Option "DynamicClocks" "on"
1174EndSection
1175</pre>
1176
1177</body>
1178</section>
948<section> 1179<section>
949<title>Wireless Power Management</title> 1180<title>Wireless Power Management</title>
950<body> 1181<body>
951 1182
952<p> 1183<p>
953Wireless LAN cards consume quite a few energy. Put them in Power Management 1184Wireless LAN cards consume quite a bit of energy. Put them in Power Management
954mode in analogy to the pm.hda script. 1185mode just like your hard drives.
955</p>
956
957<pre caption="WLAN Power Management automated">
958#!/sbin/runscript
959start() {
960 ebegin "Activating Power Management for Wireless LAN"
961 iwconfig wlan0 power on power max period 3
962 eend $?
963}
964
965stop () {
966 ebegin "Deactivating Power Management for Wireless LAN"
967 iwconfig wlan0 power off
968 eend $?
969}
970</pre>
971
972<p> 1186</p>
973Starting this script will put wlan0 in Power Management mode, going to sleep at 1187
974the latest three seconds after no traffic. 1188<note>
975Save it as <path>/etc/init.d/pm.wlan0</path> and add it to the battery runlevel 1189This script assumes your wireless interface is called <c>wlan0</c>; replace
976like the disk script above. See <c>man iwconfig</c> for details and more 1190this with the actual name of your interface.
977options. If your driver and access point support changing the beacon time, this 1191</note>
978is a good starting point to save even more energy. 1192
979</p> 1193<p>
980 1194Add the following option to <path>/etc/conf.d/net</path> to automatically enable
981<pre caption="Power Management for WLAN"> 1195power management for your wireless card:
982# <i>chmod +x /etc/init.d/pm.wlan0</i>
983# <i>/sbin/depscan.sh</i>
984# <i>rc-update add pm.wlan0 battery</i>
985</pre> 1196</p>
1197
1198<pre caption="Automated WLAN Power Management">
1199iwconfig_wlan0="power on"
1200</pre>
1201
1202<p>
1203See <c>man iwconfig</c> for details and more options like the period between
1204wakeups or timeout settings. If your driver and access point support changing
1205the beacon time, this is a good starting point to save even more energy.
1206</p>
986 1207
987</body> 1208</body>
988</section> 1209</section>
989<section> 1210<section>
990<title>USB Power Management</title> 1211<title>USB Power Management</title>
994There are two problems with USB devices regarding energy consumption: First, 1215There are two problems with USB devices regarding energy consumption: First,
995devices like USB mice, digital cameras or USB sticks consume energy while 1216devices like USB mice, digital cameras or USB sticks consume energy while
996plugged in. You cannot avoid this (nevertheless remove them in case they're not 1217plugged in. You cannot avoid this (nevertheless remove them in case they're not
997needed). Second, when there are USB devices plugged in, the USB host controller 1218needed). Second, when there are USB devices plugged in, the USB host controller
998periodically accesses the bus which in turn prevents the CPU from going into 1219periodically accesses the bus which in turn prevents the CPU from going into
999C3/4 sleep mode. The OS answer to this problem is the so called "USB selective 1220sleep mode. The kernel offers an experimental option to enable suspension of
1000suspend", which has not yet been implemented in the kernel. USB selective 1221USB devices through driver calls or one of the <path>power/state</path> files
1001suspend only allows bus accesses in case the device is in use. The cruel 1222in <path>/sys</path>.
1002workaround until it's implemented is as following: Compile USB support and 1223</p>
1003devices as modules and remove them via a script while they are not in use (e.g. 1224
1004when closing the lid). 1225<pre caption="Enabling USB suspend support in the kernel">
1226Device Drivers
1227 USB support
1228 [*] Support for Host-side USB
1229 [*] USB suspend/resume (EXPERIMENTAL)
1005</p> 1230</pre>
1006 1231
1007</body> 1232</body>
1008</section> 1233</section>
1009</chapter> 1234</chapter>
1010 1235
1011<chapter> 1236<chapter>
1012<title>Sleep states: sleep, standby, suspend to disk</title> 1237<title>Sleep States: sleep, standby, and suspend to disk</title>
1013<section> 1238<section>
1014<title>Overview</title>
1015<body> 1239<body>
1016 1240
1017<p> 1241<p>
1018ACPI defines different sleep states. The more important ones are 1242ACPI defines different sleep states. The more important ones are
1019</p> 1243</p>
1020 1244
1021<ul> 1245<ul>
1022 <li>S1 aka Standby</li> 1246 <li>S1 aka Standby</li>
1023 <li>S3 aka Suspend to RAM aka Sleep</li> 1247 <li>S3 aka Suspend to RAM aka Sleep</li>
1024 <li>S4 aka Suspend to Disk aka Hibernate</li> 1248 <li>S4 aka Suspend to Disk aka Hibernate</li>
1025</ul> 1249</ul>
1026 1250
1030</p> 1254</p>
1031 1255
1032</body> 1256</body>
1033</section> 1257</section>
1034<section> 1258<section>
1035<title>Sleep, Standby &amp; Hibernate</title> 1259<title>Sleep (S3)</title>
1036<body> 1260<body>
1037 1261
1038<p> 1262<p>
1039The ACPI support for these sleep states is marked as experimental for good 1263The ACPI support for these sleep states is marked experimental for good reason.
1040reason. APM sleep states seem to be more stable, however you can't use APM and 1264APM sleep states seem to be more stable, however you can't use APM and ACPI
1041ACPI together. 1265together.
1266</p>
1267
1268<pre caption="Kernel configuration for the various suspend types">
1269 Power Management Options ---&gt;
1270 [*] Power Management support
1271 [*] Suspend to RAM and standby
1272</pre>
1273
1274<p>
1275Once your kernel is properly configured, you can use the
1276<c>hibernate-script</c> to activate suspend or sleep mode. Let's install that
1277first.
1278</p>
1279
1280<pre caption="Installing the hibernate-script">
1281# <i>emerge hibernate-script</i>
1282</pre>
1283
1284<p>
1285Some configuration has to be done in <path>/etc/hibernate</path>. The default
1286package introduces a few configuration files for each sleep state. Options that
1287are common to all suspend methods are placed in <path>common.conf</path>; make
1288sure this file is properly set up for your system.
1289</p>
1290
1291<p>
1292To configure sleep, edit <path>sysfs-ram.conf</path> in
1293<path>/etc/hibernate</path>. <c>UseSysfsPowerState mem</c> is already setup
1294correctly, but if you need to make further changes to this particular sleep
1295state (or any other sleep state) you should add them to
1296<path>/etc/hibernate/hibernate.conf</path>. The comments and option names will
1297guide you. If you use nfs or samba shares over the network, make sure to
1298shutdown the appropriate init scripts to avoid timeouts.
1299</p>
1300
1301<note>
1302For more information on setting up sleep states, read <c>man
1303hibernate.conf</c>.
1304</note>
1305
1306<p>
1307Ready? Now is the last chance to backup any data you want to keep after
1308executing the next command. Notice that you probably have to hit a special key
1309like <c>Fn</c> to resume from sleep.
1310</p>
1311
1312<pre caption="Calling sleep">
1313# <i>hibernate-ram</i>
1314</pre>
1315
1316<p>
1317If you're still reading, it seems to work. You can also setup standby (S1) in a
1318similar way by editing <path>sysfs-ram.conf</path> and changing
1319"UseSysfsPowerState mem" to "UseSysfsPowerState standby". S3 and S4 are the more
1320interesting sleep states due to greater energy savings however.
1321</p>
1322
1323</body>
1324</section>
1325<section>
1326<title>Hibernate (S4)</title>
1327<body>
1328
1329<p>
1330This section introduces hibernation, where a snapshot of the running system is
1331written to disk before powering off. On resume, the snapshot is loaded and you
1332can go on working at exactly the point you called hibernate before.
1042</p> 1333</p>
1043 1334
1044<warn> 1335<warn>
1045Altough sleep state support is improving much, it's still rather experimental. 1336Don't exchange non hot-pluggable hardware when suspended. Don't attempt to load
1046At last I got swsusp2 and suspend to RAM to work, but be warned: This will very 1337a snapshot with a different kernel image than the one it was created with.
1047likely not work but damage your data/system. 1338Shutdown any NFS or samba server/client before hibernating.
1048</warn> 1339</warn>
1049 1340
1050<p> 1341<p>
1051There are currently three implementations for S4. The original one is swsusp, 1342There are two different implementations for S4. The original one is swsusp,
1052then there is swsusp2 which has the nicest interface (including bootsplash 1343then there is the newer tuxonice (formerly suspend2) with a nicer interface
1053support), but requires manual kernel patching. Last not least we have 1344(including fbsplash support). A <uri
1054Suspend-to-Disk, a fork of swsusp. 1345link="http://tuxonice.net/features.html#compare">feature comparison</uri> is
1055</p> 1346available at the <uri link="http://www.tuxonice.net">tuxonice homepage</uri>.
1056 1347There used to be Suspend-to-Disk (pmdisk), a fork of swsusp, but it has been
1348merged back.
1057<p> 1349</p>
1058If this confused you, have a look at a <uri 1350
1059link="http://softwaresuspend.berlios.de/features.html#compare">feature
1060comparison</uri>. If you still are confused and don't know which one to choose,
1061first give swsusp2 a try, it looks most promising.
1062</p> 1351<p>
1063 1352TuxOnIce is not included in the mainline kernel yet, therefore you either have
1353to patch your kernel sources with the patches provided by <uri
1354link="http://www.tuxonice.net">tuxonice.net</uri> or use
1355<c>sys-kernel/tuxonice-sources</c>.
1064<p> 1356</p>
1065The kernel part for this is as following: 1357
1358<p>
1359The kernel part for both swusp and TuxOnIce is as follows:
1066</p> 1360</p>
1067 1361
1068<pre caption="Kernel configuration for the various suspend types"> 1362<pre caption="Kernel configuration for the various suspend types">
1069Power Management Options ---&gt; 1363Power Management support ---&gt;
1070
1071 <comment>(sleep and standby)</comment>
1072 ACPI( Advanced Configuration and Power Interface ) Support --->
1073 [*] ACPI Support
1074 [*] Sleep States
1075
1076 <comment>(hibernate with swsusp)</comment> 1364 <comment>(hibernate with swsusp)</comment>
1077 [*] Software Suspend (EXPERIMENTAL) 1365 [*] Hibernation (aka 'suspend to disk')
1078 1366 <comment>(replace /dev/SWAP with your swap partition)</comment>
1367 (/dev/SWAP) Default resume partition
1368
1079 <comment>(hibernate with swsusp2)</comment> 1369 <comment>(hibernate with TuxOnIce)</comment>
1080 Software Suspend 2 1370 Enhanced Hibernation (TuxOnIce)
1081 --- Image Storage (you need at least one writer) 1371 --- Image Storage (you need at least one allocator)
1082 [*] Swap Writer 1372 [*] File Allocator
1083 --- Page Transformers 1373 [*] Swap Allocator
1084 [*] LZF image compression 1374 --- General Options
1085 (/dev/"your-swap-here") Default resume device name 1375 [*] Compression support
1086 1376 [ ] Allow Keep Image Mode
1087 <comment>(hibernate with Suspend-to-Disk)</comment> 1377 [*] Replace swsusp by default
1088 [*] Suspend-to-Disk Suport
1089 (/dev/"your-swap-here") Default resume partition
1090</pre> 1378</pre>
1091 1379
1092<p>
1093Compile your kernel with the appropriate options enabled and issue <c>cat
1094/proc/acpi/sleep</c> for 2.4 series respectively <c>cat /sys/power/state</c>
1095for 2.6 to find out what is supported. The latter gives me <c>standby mem
1096disk</c>. For swsusp, the kernel parameter <c>resume=/dev/"your-swap-here"</c>
1097has to be appended. If booting is not possible due to a broken image, use
1098<c>noresume</c> for swsusp, <c>pmdisk=off</c> for Suspend-to-Disk and
1099<c>noresume2</c> for swsusp2.
1100</p> 1380<p>
1101 1381The configuration for swsusp is rather easy. If you didn't store the location
1382of your swap partition in the kernel config, you can also pass it as a
1383parameter with the <c>resume=/dev/SWAP</c> directive. If booting is not
1384possible due to a broken image, use the <c>noresume</c> kernel parameter. The
1385<c>hibernate-cleanup</c> init script invalidates swsusp images during the boot
1386process.
1102<p> 1387</p>
1103To put your system in one of the sleep states, use 1388
1389<pre caption="Invalidating swsusp images during the boot process">
1390# <i>rc-update add hibernate-cleanup boot</i>
1391</pre>
1392
1104</p> 1393<p>
1105 1394To activate hibernate with swsusp, use the hibernate script and set
1106<pre caption="Activating sleep states"> 1395<c>UseSysfsPowerState disk</c> in <path>/etc/hibernate/sysfs-disk</path>.
1107<comment>(kernel 2.4 series)</comment>
1108# <i>echo 1 &gt; /proc/acpi/sleep</i> <comment>(standby)</comment>
1109# <i>echo 3 &gt; /proc/acpi/sleep</i> <comment>(sleep)</comment>
1110
1111<comment>(kernel 2.6 series)</comment>
1112# <i>echo -n standby &gt; /sys/power/state</i> <comment>(standby)</comment>
1113# <i>echo -n mem &gt; /sys/power/state</i> <comment>(sleep)</comment>
1114
1115<comment>(swsusp)</comment>
1116# <i>echo 4 &gt; /proc/acpi/sleep</i> <comment>(hibernate)</comment>
1117
1118<comment>(Suspend-to-Disk)</comment>
1119# <i>echo -n disk &gt; /sys/power/state</i> <comment>(hibernate)</comment>
1120
1121<comment>(swsusp2)</comment>
1122# <i>/usr/sbin/hibernate</i> <comment>(hibernate, see below)</comment>
1123</pre> 1396</p>
1124 1397
1125<warn> 1398<warn>
1126Backup your data before doing this. Run <c>sync</c> before executing one of the 1399Backup your data before doing this. Run <c>sync</c> before executing one of the
1127commands to have cached data written to disk. First try it outside of X, then 1400commands to have cached data written to disk. First try it outside of X, then
1128with X running, but not logged in. 1401with X running, but not logged in.
1129</warn> 1402</warn>
1130 1403
1131<p> 1404<p>
1132If you experience kernel panics due to uhci or similar, try to compile USB 1405If you experience kernel panics due to uhci or similar, try to compile USB
1133support as module and unload the modules before sending your laptop to sleep 1406support as module and unload the modules before sending your laptop to sleep
1134mode. 1407mode. There are configuration options for this in <path>common.conf</path>
1135</p>
1136
1137<p> 1408</p>
1138While the above should be sufficient to get swsusp and Suspend-to-Disk running
1139(I didn't say working), swsusp2 needs special care.
1140The first thing to do is patching the kernel with the patches provided at <uri
1141link="http://softwaresuspend.berlios.de/">
1142http://softwaresuspend.berlios.de/</uri>. Additionally you've got to emerge
1143<c>hibernate-script</c>. Once it is installed, configure
1144<path>/etc/hibernate/hibernate.conf</path> and try whether it works:
1145</p>
1146 1409
1410<pre caption="Hibernating with swsusp">
1411# <i>nano -w /etc/hibernate/common.conf</i>
1412<comment>(Make sure you have a backup of your data)</comment>
1413# <i>hibernate</i>
1147<pre> 1414</pre>
1148<i># emerge hibernate-script</i> 1415
1149<i># $EDITOR /etc/hibernate/hibernate.conf</i> 1416<p>
1150<comment>(Last chance to backup any data)</comment> 1417The following section discusses the setup of TuxOnIce including fbsplash support
1418for a nice graphical progress bar during suspend and resume.
1419</p>
1420
1421<p>
1422The first part of the configuration is similar to the configuration of swsusp.
1423In case you didn't store the location of your swap partition in the kernel
1424config, you have to pass it as a kernel parameter with the
1425<c>resume=swap:/dev/SWAP</c> directive. If booting is not possible due to a
1426broken image, append the <c>noresume</c> parameter. Additionally, the
1427<c>hibernate-cleanup</c> init script invalidates TuxOnIce images during the boot
1428process.
1429</p>
1430
1431<pre caption="Invalidating TuxOnIce images during the boot process">
1432# <i>rc-update add hibernate-cleanup boot</i>
1433</pre>
1434
1435<p>
1436Now edit <path>/etc/hibernate/tuxonice.conf</path>, enable the <c>TuxOnIce</c>
1437options you need. Do not enable the <c>fbsplash</c> options in
1438<c>common.conf</c> just yet.
1439</p>
1440
1441<pre caption="Hibernating with TuxOnIce">
1442# <i>nano -w /etc/hibernate/tuxonice.conf</i>
1443<comment>(Make sure you have a backup of your data)</comment>
1151<i># hibernate</i> 1444# <i>hibernate</i>
1445</pre>
1446
1447<p>
1448Please configure <c>fbsplash</c> now if you didn't do already. To enable
1449fbsplash support during hibernation, the <c>sys-apps/tuxonice-userui</c> package
1450is needed. Additionally, you've got to enable the <c>fbsplash</c> USE flag.
1152</pre> 1451</p>
1452
1453<pre caption="Installing tuxonice-userui">
1454# <i>echo "sys-apps/tuxonice-userui fbsplash" >> /etc/portage/package.use</i>
1455# <i>emerge tuxonice-userui</i>
1456</pre>
1457
1458<p>
1459The ebuild tells you to make a symlink to the theme you want to use. For
1460example, to use the <c>livecd-2005.1</c> theme, run the following command:
1461</p>
1462
1463<pre caption="Using the livecd-2005.1 theme during hibernation">
1464# <i>ln -sfn /etc/splash/livecd-2005.1 /etc/splash/tuxonice</i>
1465</pre>
1466
1467<p>
1468If you don't want a black screen in the first part of the resume process, you
1469have to add the <c>tuxoniceui_fbsplash</c> tool to your initrd image. Assuming
1470you created the initrd image with <c>splash_geninitramfs</c> and saved it as
1471<path>/boot/fbsplash-emergence-1024x768</path>, here's how to do that.
1472</p>
1473
1474<pre caption="Adding tuxoniceui_fbsplash to an initrd image">
1475# <i>mount /boot</i>
1476# <i>mkdir ~/initrd.d</i>
1477# <i>cp /boot/fbsplash-emergence-1024x768 ~/initrd.d/</i>
1478# <i>cd ~/initrd.d</i>
1479# <i>gunzip -c fbsplash-emergence-1024x768 | cpio -idm --quiet -H newc</i>
1480# <i>rm fbsplash-emergence-1024x768</i>
1481# <i>cp /usr/sbin/tuxoniceui_fbsplash sbin/</i>
1482# <i>find . | cpio --quiet --dereference -o -H newc | gzip -9 > /boot/fbsplash-tuxonice-emergence-1024x768</i>
1483</pre>
1484
1485<p>
1486Afterwards adjust <path>grub.conf</path> (or <path>lilo.conf</path>) so that
1487your TuxOnIce kernel uses
1488<path>/boot/fbsplash-tuxonice-emergence-1024x768</path> as initrd image. You can
1489now test a dry run to see if everything is setup correctly.
1490</p>
1491
1492<pre caption="Test run for fbsplash hibernation">
1493# <i>tuxoniceui_fbsplash -t</i>
1494</pre>
1495
1496<p>
1497Afterwards open <path>/etc/hibernate/common.conf</path> and activate the
1498fbsplash options. Execute <c>hibernate</c> and enjoy.
1499</p>
1153 1500
1154</body> 1501</body>
1155</section> 1502</section>
1156</chapter> 1503</chapter>
1157 1504
1158<chapter> 1505<chapter>
1159<title>Troubleshooting</title> 1506<title>Troubleshooting</title>
1160<section> 1507<section>
1161<title>If things go wrong...</title>
1162<body> 1508<body>
1163 1509
1164<p> 1510<p>
1165<e>Q:</e> I'm trying to change the CPU frequency, but 1511<e>Q:</e> I'm trying to change the CPU frequency, but
1166<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor</path> does not 1512<path>/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor</path> does not
1168</p> 1514</p>
1169 1515
1170<p> 1516<p>
1171<e>A:</e> Make sure your processor supports CPU frequency scaling and you chose 1517<e>A:</e> Make sure your processor supports CPU frequency scaling and you chose
1172the right CPUFreq driver for your processor. Here is a list of processors that 1518the right CPUFreq driver for your processor. Here is a list of processors that
1173are supported by cpufreq (kernel 2.6.7): ARM Integrator, ARM-SA1100, 1519are supported by cpufreq (kernel 2.6.7): ARM Integrator, ARM-SA1100, ARM-SA1110,
1174ARM-SA1110, AMD Elan - SC400, SC410, AMD mobile K6-2+, AMD mobile K6-3+, AMD 1520AMD Elan - SC400, SC410, AMD mobile K6-2+, AMD mobile K6-3+, AMD mobile Duron,
1175mobile Duron, AMD mobile Athlon, AMD Opteron, AMD Athlon 64, Cyrix Media GXm, 1521AMD mobile Athlon, AMD Opteron, AMD Athlon 64, Cyrix Media GXm, Intel mobile
1176Intel mobile PIII and Intel mobile PIII-M on certain chipsets, Intel Pentium 4, 1522PIII and Intel mobile PIII-M on certain chipsets, Intel Pentium 4, Intel Xeon,
1177Intel Xeon, Intel Pentium M (Centrino), National Semiconductors Geode GX, 1523Intel Pentium M (Centrino), National Semiconductors Geode GX, Transmeta Crusoe,
1178Transmeta Crusoe, VIA Cyrix 3 / C3, UltraSPARC-III, SuperH SH-3, SH-4, several 1524VIA Cyrix 3 / C3, UltraSPARC-III, SuperH SH-3, SH-4, several "PowerBook" and
1179"PowerBook" and "iBook2" and various processors on some ACPI 2.0-compatible 1525"iBook2" and various processors on some ACPI 2.0-compatible systems (only if
1180systems (only if "ACPI Processor Performance States" are available to the 1526"ACPI Processor Performance States" are available to the ACPI/BIOS interface).
1181ACPI/BIOS interface).
1182</p> 1527</p>
1183 1528
1184<p> 1529<p>
1185<e>Q:</e> My laptop supports frequency scaling, but 1530<e>Q:</e> My laptop supports frequency scaling, but
1186<path>/sys/devices/system/cpu/cpu0/cpufreq/</path> is empty. 1531<path>/sys/devices/system/cpu/cpu0/cpufreq/</path> is empty.
1191Try to update the BIOS, especially if a broken DSDT is reported. You can also 1536Try to update the BIOS, especially if a broken DSDT is reported. You can also
1192try to fix it yourself (which is beyond the scope of this guide). 1537try to fix it yourself (which is beyond the scope of this guide).
1193</p> 1538</p>
1194 1539
1195<p> 1540<p>
1196<e>Q:</e> My laptop supports frequency scaling, but according to /proc/cpuinfo 1541<e>Q:</e> My laptop supports frequency scaling, but according to
1197the speed never changes. 1542<path>/proc/cpuinfo</path> the speed never changes.
1198</p> 1543</p>
1199 1544
1200<p> 1545<p>
1201<e>A:</e> Probably you have activated symmetric multiprocessing support 1546<e>A:</e> Probably you have activated symmetric multiprocessing support
1202(CONFIG_SMP) in your kernel. Deactivate it and it should work. Some older 1547(CONFIG_SMP) in your kernel. Deactivate it and it should work. Some older
1203kernels had a bug causing this. In that case, run <c>emerge x86info</c>, 1548kernels had a bug causing this. In that case, run <c>emerge x86info</c>, update
1204update your kernel as asked and check the current frequency with 1549your kernel as asked and check the current frequency with <c>x86info -mhz</c>.
1205<c>x86info -mhz</c>.
1206</p> 1550</p>
1207 1551
1208<p> 1552<p>
1209<e>Q:</e> I can change the CPU frequency, but the range is not as wide as in 1553<e>Q:</e> I can change the CPU frequency, but the range is not as wide as in
1210another OS. 1554another OS.
1211</p> 1555</p>
1212 1556
1213<p> 1557<p>
1214<e>A:</e> You can combine frequency scaling with ACPI throttling to get a lower 1558<e>A:</e> You can combine frequency scaling with ACPI throttling to get a lower
1215minimum frequency. Notice that throttling doesn't save much energy and is 1559minimum frequency. Notice that throttling doesn't save much energy and is mainly
1216mainly used for thermal management (keeping your laptop cool and quiet). You 1560used for thermal management (keeping your laptop cool and quiet). You can read
1217can read the current throttling state with <c>cat 1561the current throttling state with <c>cat /proc/acpi/processor/CPU/throttling</c>
1218/proc/acpi/processor/CPU/throttling</c> and change it with <c>echo -n "0:x" > 1562and change it with <c>echo -n "0:x" > /proc/acpi/processor/CPU/limit</c>, where
1219/proc/acpi/processor/CPU/limit</c>, where x is one of the Tx states listed in 1563x is one of the Tx states listed in
1220<path>/proc/acpi/processor/CPU/throttling</path>. 1564<path>/proc/acpi/processor/CPU/throttling</path>.
1221</p> 1565</p>
1222 1566
1223<p> 1567<p>
1224<e>Q:</e> When configuring the kernel, powersave, performance and userspace 1568<e>Q:</e> When configuring the kernel, powersave, performance and userspace
1229<e>A:</e> The ondemand governor is only included in recent kernel sources. Try 1573<e>A:</e> The ondemand governor is only included in recent kernel sources. Try
1230updating them. 1574updating them.
1231</p> 1575</p>
1232 1576
1233<p> 1577<p>
1234<e>Q:</e> Runlevel switching doesn't work - the script is not able to determine
1235the power source correctly.
1236</p>
1237
1238<p>
1239<e>A:</e> On some systems, the power source can't be determined by reading
1240<path>/proc/acpi/ac_adapter/*/state</path>. If it fails for you, create a
1241custom script <c>on_ac_power</c> or use the one from <c>powermgmt-base</c>.
1242An ebuild can be found in <uri
1243link="http://bugs.gentoo.org/show_bug.cgi?id=76516">Bug #76516</uri>. You
1244only have to emerge it, it works transparently with the above script.
1245</p>
1246
1247<p>
1248<e>Q:</e> Battery life time seems to be worse than before. 1578<e>Q:</e> Battery life time seems to be worse than before.
1249</p> 1579</p>
1250 1580
1251<p> 1581<p>
1252<e>A:</e> Check your BIOS settings. Maybe you forgot to re-enable some of the 1582<e>A:</e> Check your BIOS settings. Maybe you forgot to re-enable some of the
1262<e>A:</e> Check that battery support is compiled into your kernel. If you use 1592<e>A:</e> Check that battery support is compiled into your kernel. If you use
1263it as a module, make sure the module is loaded. 1593it as a module, make sure the module is loaded.
1264</p> 1594</p>
1265 1595
1266<p> 1596<p>
1597<e>Q:</e> My system logger reports things like "logger: ACPI group battery /
1598action battery is not defined".
1599</p>
1600
1601<p>
1602<e>A:</e> This message is generated by the <path>/etc/acpi/default.sh</path>
1603script that is shipped with acpid. You can safely ignore it. If you like to get
1604rid of it, you can comment the appropriate line in
1605<path>/etc/acpi/default.sh</path> as shown below:
1606</p>
1607
1608<pre caption="Disabling warnings about unknown acpi events">
1609 *) # logger "ACPI action $action is not defined"
1610</pre>
1611
1612<p>
1267<e>Q:</e> I have a Dell Inspiron 51XX and I don't get any ACPI events. 1613<e>Q:</e> I have a Dell Inspiron 51XX and I don't get any ACPI events.
1268</p> 1614</p>
1269 1615
1270<p> 1616<p>
1271<e>A:</e> This seems to be a kernel bug. Read on <uri 1617<e>A:</e> This seems to be a kernel bug. Read on <uri
1272link="http://bugme.osdl.org/show_bug.cgi?id=1752">here</uri>. 1618link="http://bugme.osdl.org/show_bug.cgi?id=1752">here</uri>.
1273</p> 1619</p>
1274 1620
1275<p> 1621<p>
1622<e>Q:</e> I activated the <c>DynamicClocks</c> option in <path>xorg.conf</path>
1623and now X.org crashes / the screen stays black / my laptop doesn't shutdown
1624properly.
1625</p>
1626
1627<p>
1628<e>A:</e> This happens on some systems. You have to disable
1629<c>DynamicClocks</c>.
1630</p>
1631
1632<p>
1633<e>Q:</e> I want to use TuxOnIce, but it tells me my swap partition is too
1634small. Resizing is not an option.
1635</p>
1636
1637<p>
1638<e>A:</e> If there is enough free space on your system, you can use the
1639filewriter instead of the swapwriter. The <c>hibernate-script</c> supports it as
1640well. More information can be found in
1641<path>/usr/src/linux/Documentation/power/tuxonice.txt</path>.
1642</p>
1643
1644<p>
1276<e>Q:</e> I just bought a brand new battery, but it only lasts for some 1645<e>Q:</e> I just bought a brand new battery, but it only lasts for some
1277minutes! What am I doing wrong? 1646minutes! What am I doing wrong?
1278</p> 1647</p>
1279 1648
1280<p> 1649<p>
1281<e>A:</e> First follow your manufacturer's advice on how to charge the battery 1650<e>A:</e> First follow your manufacturer's advice on how to charge the battery
1282correctly. 1651correctly.
1283</p> 1652</p>
1284 1653
1285<p> 1654<p>
1286<e>Q:</e> The above didn't help. What should I do then? 1655<e>Q:</e> The above didn't help. What should I do then?
1287</p> 1656</p>
1304<p> 1673<p>
1305<e>Q:</e> My problem is not listed above. Where should I go next? 1674<e>Q:</e> My problem is not listed above. Where should I go next?
1306</p> 1675</p>
1307 1676
1308<p> 1677<p>
1309<e>A:</e> Don't fear to contact me, <mail link="fragfred@gmx.de">Dennis 1678<e>A:</e> Don't fear to contact me, <mail link="earthwings@gentoo.org">Dennis
1310Nienhüser</mail>, directly. 1679Nienhüser</mail>, directly. The <uri link="http://forums.gentoo.org">Gentoo
1680Forums</uri> are a good place to get help as well. If you prefer IRC, try the
1681<c>#gentoo-laptop</c> <uri link="irc://irc.gentoo.org">channel</uri>.
1311</p> 1682</p>
1312 1683
1313</body> 1684</body>
1314</section> 1685</section>
1315</chapter> 1686</chapter>

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