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@@ -1,1762 +1 @@
-
-
-
-Battery-Powered
-
-
-
-----
-
-!!!Battery Powered Linux Mini-HOWTO
-
-!!Hanno Mueller,
-
-hanno@lava.de
-
-http://www.lava.de/~hanno/v, 21 December 1997
-
-
-----
-''This document describes how to reduce a Linux system's power
-consumption by tweaking some of its configuration settings. This
-will be helpful for everyone who runs Linux on a portable
-computer system. There is also some general information about
-how to take care of your battery. If you are using Linux on a
-desktop system, you probably don't need to read all this.''
-----
-
-
-
-
-!!1. Introduction
-
-
-*1.1 Before you ask
-
-*1.2 What this document is about
-
-*1.3 Roadmap
-
-*1.4 Feedback
-
-*1.5 Disclaimer
-
-*1.6 Copyright
-
-
-
-
-
-!!2. General information
-
-
-*2.1 Be kind to your battery
-
-*2.2 Power saving - The obvious stuff
-
-
-
-
-
-!!3. Advanced Power Management
-
-
-*3.1 What APM can do for you
-
-*3.2 How to activate APM support in Linux
-
-*3.3 APM support and the PCMCIA drivers
-
-*3.4 The apmd package
-
-*3.5 And if my laptop does not support APM?
-
-
-
-
-
-!!4. Changing some general system settings
-
-
-*4.1 The crond daemon and atrun
-
-*4.2 The update / bdflush daemon
-
-*4.3 The syslogd daemon
-
-*4.4 The init command
-
-*4.5 The swap partition
-
-*4.6 The apache httpd webserver daemon
-
-*4.7 The XFree86 package
-
-*4.8 The emacs editor
-
-*4.9 How to find more ways to optimize
-
-
-
-
-
-!!5. Appendix
-
-
-*5.1 A message to Linux distributors
-
-*5.2 Credits
-
-*5.3 About this document
-
-----
-
-!!1. Introduction
-
-
-
-
-
-``Ages 6 and up. Batteries included.''
-
-
-
-
-
-
-
-!!1.1 Before you ask
-
-
-
-
-
-
-This document does not describe how to install Linux on
-laptops, but how to optimize a ready-configured Linux for
-use on laptops. Please read the ''Installation-HOWTO'' or your
-distributor's handbook for help with installing Linux.
-
-
-
-
-
-This document does not describe how to use an uninterruptable
-power supply and the powerd daemon, either (even though
-a ups is a big battery). Read the ''UPS-HOWTO'' for details
-about that subject.
-
-
-
-
-
-
-
-!!1.2 What this document is about
-
-
-
-
-
-
-More and more people own portable computers these days and in
-turn, more and more people install Linux on such machines.
-
-
-
-
-
-Installing and using Linux on a laptop is usually no problem at
-all, so go ahead and give it a try. Unlike some other operating
-systems, Linux still supports and runs well on even very old
-hardware, so you might give your outdated portable a new
-purpose in life by installing Linux on it.
-
-
-
-
-
-If you need help with installing Linux on a laptop or if you
-have questions about laptop hardware, you can check the
-excellent ''Linux Laptop webpage'' at
-
-http://www.cs.utexas.edu/users/kharker/linux-laptop/
-where you will find a lot of useful information and detailed
-help. The Linux Laptop page describes hardware configuration
-for specific laptop models and chipsets.
-
-
-
-
-
-This HOWTO however will focus on the one problem that is
-common to all portable systems: ''Power consumption''.
-
-
-
-
-
-Yet, I have not found a Linux distribution that comes with a
-configuration ''optimized'' for laptops. Since I could not find this
-kind of information anywhere else, I have started to collect a
-few simple but effective tricks that will help you save battery
-power and in turn increase your system's uptime while running
-on battery.
-
-
-
-
-
-(Sidenote. I received a complaint by a reader that these tips were
-not very effective with his laptop. So does all this really
-work? Yes, but don't expect miracles. I was able to increase my
-laptop's battery time from 90 minutes to more than 120
-minutes.)
-
-
-
-
-
-
-
-!!1.3 Roadmap
-
-
-
-
-
-
-If you are a laptop pro, you can probably skip the
-General Information section. If
-you are a Linux pro, what you really want to know can be found in the
-Changing some general system settings
-section. If you are a Linux distributor, please read
-A message to Linux distributors.
-
-
-
-
-
-
-
-!!1.4 Feedback
-
-
-
-
-
-
-Your feedback is welcome. Please send comments to
-
-hanno@lava.de. Did
-it work on your system? Do you have new tips? Are there any outdated links
-or addresses in this text?
-
-
-
-
-
-I am sorry, but I will not be able to help you
-with questions about specific laptop models. I don't claim
-to be a laptop guru, I just happen to own one laptop myself
-and I simply want to share the information I collected. Please
-check the Linux Laptop webpage first, probably someone else has
-already written a page dedicated to your model. Ask your
-manufacturer's technical support. Or go the the laptop newsgroup
-
-comp.sys.laptops
-and ask there.
-
-
-
-
-
-
-
-!!1.5 Disclaimer
-
-
-
-
-
-
-All methods described here were tested by me and worked fine
-on my laptop, unless noted otherwise. However, I cannot
-guarantee that any of this won't crash or seriously damage
-your system. Life is dangerous, so keep backup copies of
-your important files before playing with your Linux
-configuration. If things go wrong, I do not take any
-responsibility for your data loss. In other words: Don't
-sue me. Thank you.
-
-
-
-
-
-
-
-!!1.6 Copyright
-
-
-
-
-
-
-This document shall be distributed under the standard
-HOWTO-copyright notice, found in the HOWTO folder at
-
-http://sunsite.unc.edu/mdw/linux.html.
-
-
-
-
-
-
-----
-
-!! 2. General information
-
-
-
-
-
-This section describes a few technical things about laptop
-batteries and some general power saving tips. This information
-is not Linux-specific and if you are experienced with
-laptops, you might already know all this.
-
-
-
-
-
-
-
-!!2.1 Be kind to your battery
-
-
-
-
-
-
-(Please note the
-credits for this
-section.)
-
-
-
-
-
-There are currently three types of batteries commonly used
-for portable computers.
-
-
-
-
-
-
-
-
-*''!NiCd'' batteries were the standard technology for years, but
-today they are out of date and new laptops don't use them
-anymore. They are heavy and very prone to the
-``memory effect''. When recharging a !NiCd battery that has not
-been fully discharged, it ``remembers'' the old charge and
-continues there the next time you use it.
-
-
-
-
-The memory effect is caused by crystallization of the
-battery's substances and can permanently reduce your battery's
-lifetime, even make it useless. To avoid it, you should
-completely discharge the battery and then fully recharge it again
-at least once every few weeks.
-
-
-
-
-
-(A sidenote about the memory effect. James Youngman knows of a rather
-drastic method to - uhm - ``repair'' batteries: ``If your !NiCd
-battery is suffering from the memory effect, remove it from your
-computer, hold it about 30cm above a desk or the floor, and drop
-it (make sure it lands flat).'' He says that this will break the
-whiskers that have formed in the battery and that are the cause of
-the memory effect if your battery is already affected
-by it. ``I don't know if this works for non-!NiCd batteries or not.'')
-
-
-Cadmium is a very hazardous poison, but if returned
-to your dealer, the material can almost be fully recycled.
-
-
-
-
-
-Just in case you might be interested, here are some specs for !NiCd:
-
-
-
-
-
-Cell voltage: 1,2 V
-Energy / mass: 40 Wh/kg
-Energy / volume: 100 Wh/l
-max. Energy: 20 Wh
-Charge temp.: 10 to 35 C (50 to 95 F)
-Discharge temp.: -20 to 50 C (-5 to 120 F)
-Storage temp.: 0 to 45 C (30 to 115 F)
-
-
-
-
-
-
-
-
-
-*
-
-*''!NiMh'' batteries are the current standard used in most low
-price laptops to date. They can be made smaller and are less
-affected by the memory effect than !NiCd.
-
-
-
-
-However, they have problems at very high or low room
-temperatures. And even though they use less hazardous
-and non-poisonous substances, they cannot be fully
-recycled yet (but this will probably change in the future).
-
-
-
-
-
-!NiMh specs:
-
-
-
-
-
-Cell voltage: 1,2 V
-Energy / mass: 55 Wh/kg
-Energy / volume: 160 Wh/l
-max. Energy: 35 Wh
-Charge temp.: 10 to 35 C (50 to 95 F)
-Discharge temp.: 0 to 45 C (30 to 115 F)
-Storage temp.: 0 to 30 C (30 to 85 F)
-
-
-
-
-
-
-
-
-
-*
-
-*The new high performance batteries use ''!LiIon''
-technology. In theory, there is no memory effect at all
-with these batteries, but on occasion, they seem to have similar
-problems. Their substances are non-hazardous to the
-enviroment, but they should be returned for recycling as well.
-
-
-
-
-!LiIon specs:
-
-
-
-
-
-Cell voltage: 3,6 V
-Energy / mass: 100 Wh/kg
-Energy / volume: 230 Wh/l
-max. Energy: 60 Wh
-Charge temp.: 0 to 45 C (30 to 115 F)
-Discharge temp.: -20 to 60 C (-5 to 140 F)
-Storage temp.: -20 to 60 C (-5 to 140 F)
-
-
-
-
-
-
-
-
-
-*
-
-
-
-Even if the battery case looks the same, you cannot just
-upgrade to another battery technology. The recharging
-process is different for the kind of battery you use.
-
-
-
-
-
-Some
-manufacturers integrate the recharging circuit inside the
-laptop's external ac adapter, so you might just get away
-with buying a new power supply to upgrade. A good
-indication for an external recharging unit is when your ac
-adapter uses a proprietary connector with a lot of power
-lines.
-
-
-
-
-
-Other manufacturers
-put the recharging unit inside the laptop case where users
-cannot simply replace it with a newer technology. If
-your ac adapter only uses two power lines to connect to
-the computer (just like mine), the recharging unit is
-probably inside the laptop.
-
-
-
-
-
-When in doubt, ask your manufacturer
-if your laptop supports a more modern battery.
-
-
-
-
-
-A battery that is not used for a long time will
-slowly discharge itself. And even with greatest care, a
-battery needs to be replaced after 500 to 1000
-recharges. But still it is not recommended to run a laptop
-without the battery while on ac power - the battery often
-serves as a big capacitor to protect against voltage peaks
-from your ac outlet.
-
-
-
-
-
-As the manufacturers change the shapes of their batteries
-every few months, you might have problems to find a new
-battery for your laptop in a few years from now. Buy a
-spare battery now - before it's out of stock.
-
-
-
-
-
-
-
-!!2.2 Power saving - The obvious stuff
-
-
-
-
-
-
-There are some obvious things that you can do to reduce your system's
-power consumption. Well, maybe not so obvious, since not very many
-people follow these rules...
-
-
-
-
-
-
-
-
-*Decrease or turn off your display's backlight when you
-don't need it. By the way, tft displays use more power than
-dstn (so now you have a fine excuse why you bought the cheaper
-laptop...).
-
-
-
-
-(David Bateman tells me that using a crt screen while on battery and
-turning off the laptop display will extend battery time by about 30%:
-``Not that this is a very useful piece of knowledge though, if you've
-got the crt plugged in then why not the laptop too.'')
-
-
-
-
-*
-
-*How much processing power do you really need? I doubt that
-you will be doing very much more than text editing when on
-the road (well, at least I don't compile linux kernels then). While
-on battery, reducing the cpu clock speed will decrease power
-consumption, too. Quite a few laptops offer a cpu clock
-selector that will toggle between normal and slow speed.
-
-
-
-
-
-
-*
-
-*Turn off the cpu cooler (if you have one). Many recent laptops
-offer a bios option called ``cooling control''. If your
-system's cpu is becoming too hot, this option allows you to
-have it cooled by a tiny fan (setting ``performance'') or
-to have its cpu clock slowed down (setting ``silence''). To
-increase your uptime while on battery, use ``silence''.
-
-
-
-
-
-
-*
-
-*Avoid using external devices (printer, crt screen, zip drive, portable
-camera etc.) with your computer while on battery. When
-connected to a standard ink jet printer, my laptop's
-battery time is reduced from up to 120 minutes down to
-20 minutes.
-
-
-
-
-
-
-*
-
-*Avoid using any built in device unless necessairy: Diskette
-drive, harddisk, cd-rom. Especially cd-rom access will
-dramatically decrease your battery time.
-
-
-
-
-
-
-*
-
-*Pcmcia cards can also consume a lot of power, so don't
-leave your modem or network adapter plugged in when it
-is not in use. But this is different between the various
-pcmcia manufacturers, so check the product specs before you buy
-(e. g. some cards never turn themselves off even when
-not in use).
-
-
-
-
-(By the way, I recently read that pcmcia cards are the
-biggest problem for windows ce palmtops - they drain so
-much power that the tiny machines' little batteries have
-to be replaced within minutes...)
-
-
-
-
-
-
-
-*
-
-*Use simple software. A full blown multimedia application
-will create a lot more system load and harddisk / cd-rom
-activity than a small simple word processor.
-
-
-
-
-
-
-*
-
-*Grant Taylor has a tip for those of us who want to upgrade
-their system: ``Newer versions of some upgradable components
-consume less power. For example, IBM's Travelstar 2.5 inch 1.6
-gigabyte ide harddisk drive consumes 20 percent less than the
-500 megabyte toshiba harddisk my laptop came with.''
-
-
-
-
-
-
-*
-
-*If you are yet about to buy a laptop - don't buy a laptop
-with a 2nd level cache if battery uptime is important. A
-computer with 2nd level cache is about 10% to 20% faster
-and it will be a lot better with multimedia
-applications and number crunching, but it consumes a lot of
-power. Bjoern Kriews tells me that he has two almost
-identical laptops and the one without cache ram runs
-4h30 compared to 2h30 with cache.
-
-
-
-
-If you already have 2nd level cache installed, turning
-it off will probably not help you very much.
-Give it a try and write me about your experience.
-
-
-
-
-
-
-
-*
-
-*Another tip for those still buying a laptop - don't buy the
-latest, fastest cpu type. Usually, the older generations are
-optimized by the manufacturer after some time without
-notice. The ``new'' versions of old cpu types often create
-less heat and consume less power than the product's
-premiere version.
-
-
-
-
-There are also frankenstein laptops
-available that use cpus not optimized for portable systems. As
-I wrote this in May 97, the newest generation pentium-200
-laptops ran about 20 minutes on battery and became so hot that
-they burnt your lap. When writing the second revision
-in Oct 97, pentium-233 laptops run two hours
-or longer without ac power. Go figure.
-
-
-
-
-
-
-
-*
-
-
-
-Well, you get the idea. Most of these are restrictions
-that will probably stop you from doing any serious work
-with your Linux system. (The best way to save power
-while on battery is... not to do anything at all. That
-increases my laptop's battery uptime by almost 100 percent.)
-
-
-
-
-
-So let's go ahead to some other, more useful measures that will
-save power without disturbing your work.
-
-
-
-
-
-
-----
-
-!!3. Advanced Power Management
-
-
-
-
-
-Portable systems in general, but even many desktop computers
-come equipped with support for
-apm, the ``advanced power management'' scheme. This section
-describes how to activate apm support in your Linux
-kernel. People who are experienced with Linux may find this
-section rather boring and want to skip to the next.
-
-
-
-
-
-
-
-!!3.1 What APM can do for you
-
-
-
-
-
-
-I won't describe it in detail here, check the
-''Linux APM drivers page'' at
-
-http://www.cs.utexas.edu/users/kharker/linux-laptop/apm.html
-for more
-information. All that you need to know is that with the
-help of apm, the cpu can tell the bios when there's nothing
-really exciting going on so that the bios can take care of
-some power saving by itself - e. g. reducing the cpu clock, turning
-off the harddisk, turning off the display's backlight etc.
-
-
-
-
-
-Apm is also responsible for the ``system suspend''
-(or ``sleep'') mode and for the ``suspend to disk''
-(or ``hiberntation'') mode. And yet
-another cool, though not very important feature is
-that with the help of apm, shutdown -h will not just
-halt your system, but also turn it off.
-
-
-
-
-
-(By the way, most Linux systems put a shutdown -r in
-their /etc/inittab and map it to pressing
-control-alt-delete. I prefer having shutdown -h
-there, so when pressing the famous key combination, my laptop
-simply turns itself off.)
-
-
-
-
-
-Not all manufacturers implement a correct apm bios, so some
-laptops have trouble with the Linux apm drivers (if your
-machine has trouble with apm, it will most likely either lock
-up at Linux' boot up or after returning from suspend). If you are
-not sure, check the Linux laptop page for your specific
-model.
-
-
-
-
-
-
-
-!!3.2 How to activate APM support in Linux
-
-
-
-
-
-
-It's easy - just recompile the Linux kernel. Check the
-Kernel-HOWTO if you don't know how to do that.
-
-
-
-
-
-When the configuration script reaches the ``character
-devices'' section, the default setting for full apm
-bios support in kernel version 2..30 or higher is:
-
-
-
-
-
-
-
-
-Advanced Power Management BIOS support: Yes
-Ignore USER SUSPEND: No
-Enable PM at boot time: Yes
-Make CPU Idle calls when idle: Yes
-Enable console blanking using APM: Yes
-Power off on shutdown: Yes
-
-
-
-
-
-
-
-Please read the configuration script's help texts. They explain
-in detail what each option does, so I won't repeat them here.
-
-
-
-
-
-If your system does not fully support the apm bios standard, some
-of those options might crash your system. Test all apm features
-with the new kernel to make sure that everything works as it
-should.
-
-
-
-
-
-(A
- sidenote
-about console blanking: David Bateman tells me that
-you should not enable it because it can cause problems with the
-current version of XFree 3.2: ``The symptoms are that the screen
-will be blank when X starts, and it can be fixed usually by just
-hitting a key. It's a small but annoying problem. The next relase
-of XFree, will have pretty good DPMS support for a lot of laptop
-chipset, which should include code to turn off the LCD. Check out
-the manpage for xset in XFree 3.2A.'' David also notes that
-the lifetime of your display's backlight is determined by the number
-of times it's switched on and off: ``So its a compromise, lifetime
-of the battery versus lifetime of the backlight.'')
-
-
-
-
-
-(''Update:'' With XFree 3.3, this problem still remained on my
-laptop. I am told that this will be fixed in a future kernel
-version.)
-
-
-
-
-
-
-
-!!3.3 APM support and the PCMCIA drivers
-
-
-
-
-
-
-After recompiling the kernel, don't forget to recompile
-the linux pcmcia drivers as well.
-
-
-
-
-
-The precompiled pcmcia
-drivers that come with most linux distribution have apm
-support disabled, so that the bios can't instruct your card
-adapters to turn off.
-
-
-
-
-
-Also, you must recompile the drivers
-if you upgrade to a new kernel version and your old kernel
-was compiled with module version information turned on (this
-option is found in the ``loadable module support''
-section of the kernel configuration).
-
-
-
-
-
-Read the PCMCIA-HOWTO for detailed
-instructions on how to compile the drivers or go to the
-''Linux PCMCIA drivers homepage'' at
-
-http://hyper.stanford.edu/!HyperNews/get/pcmcia/home.html.
-
-
-
-
-
-
-
-!!3.4 The apmd package
-
-
-
-
-
-
-Now that you have APM support installed, go and get the apmd package
-from the ''Linux APM drivers page''. You don't really need it, but
-it is a very useful collection of programs. The apmd daemon logs your
-battery's behaviour and it will send out a warning if you are on
-low power. The apm command will suspend your system with a
-shell command and xapm shows the current state of your battery.
-
-
-
-
-
-(BTW, if you have problems with pcmcia cards after returning from
-suspend, you
-can check out an alternative apmd package at
-
-http://www.cut.de/bkr/linux/apmd/apmd.html. It unloads the
-pcmcia driver module before going to suspend and reloads the module
-on resume.)
-
-
-
-
-
-Grant Taylor has been playing a little with the apmd
-package and came up with helpful tips.
-
-
-
-
-
-He found that his laptop's harddisk forgets its hdparm -S
-standby period when returning from suspend: ``I modified apmd to
-reset this setting on each resume. This may be system-specific;
-but it's an important thing to do...''
-
-
-
-
-
-(Note: On my own laptop, the bios takes care of the harddisk standby
-period and resets the value on resuming. So I could not test if this
-little problem is system-specific. If it happens to you as
-well, send me a message.)
-
-
-
-
-
-Grant also had a nice trick for screen blanking with
-the XFree86 package and
-the help of the apmd package, you'll find it there.
-
-
-
-
-
-
-
-!!3.5 And if my laptop does not support APM?
-
-
-
-
-
-
-If your computer's bios does not offer any power saving
-settings (even the old ones without apm should at least allow
-to set harddisk and display standby), you can
-use hdparm -S to define your harddisk's standby period. This
-will already help a lot, since harddisk activity
-consumes a lot of power. Your system should have hdparm
-installed, so read man hdparm for the command syntax.
-
-
-
-
-
-
-----
-
-!! 4. Changing some general system settings
-
-
-
-
-
-After I got Linux up and running on my laptop, I found
-it accessing the harddisk every few seconds, even when there was
-no user logged in to the system. The harddisk could never
-enter its power saving mode. Reducing harddisk activity
-can greatly increase the battery runtime, so this is why I
-collected the following recipes.
-
-
-
-
-
-I tested all this with !RedHat 4.1, the locations of some
-configuration settings may be different for your
-distribution. (If so, please let me know.)
-
-
-
-
-
-
-
-!!4.1 The crond daemon and atrun
-
-
-
-
-
-
-Check your /etc/crontab file if it starts a process
-every minute. You will often find atrun there.
-
-
-
-
-
-With the at command, you can spool commands that must be
-invoked some time in the future. Some Linux systems use a
-dedicated atd daemon to take care of this, others
-(e. g. !RedHat) let the crond daemon run atrun once every
-minute.
-
-
-
-
-
-This is not really necessairy on most systems, since at
-commands rarely depend upon being invoked on exact time. So
-if you find a line like this in your /etc/crontab:
-
-
-
-
-
-# Run any at jobs every minute
-* * * * * root
[[ -x /usr/sbin/atrun
] && /usr/sbin/atrun
-
-
-
-
-
-
-
-Then you can safely change this to:
-
-
-
-
-
-# Run any at jobs every hour
-00 * * * * root [[ -x /usr/sbin/atrun ] && /usr/sbin/atrun
-
-
-
-
-
-
-
-Read man 5 crontab for details. Some folks can even
-work fine without the crond daemon, so if you know
-what you are doing, you might want
-to consider disabling it completely.
-
-
-
-
-
-
-
-!!4.2 The update / bdflush daemon
-
-
-
-
-
-
-Linux deals with a lot of open file buffers at any given
-moment, so the system must make sure that file changes are saved
-to the harddisk as soon possible. Otherwise, those changes
-will be lost after a system crash.
-
-
-
-
-
-The update / bdflush daemon takes care of this. (These
-are two names for the same program, so you can use either
-name to start the daemon). The default settings will make
-this daemon call flush every 5 seconds and sync every
-30 seconds.
-
-
-
-
-
-With my Fujitsu disk this caused non-stop access. (It
-seems that this harddisk flushes its ram cache even when
-nothing has changed. But this depends on your harddisk's
-firmware: Other people told me that their harddisk does enter
-its power saving mode even without the following modification.)
-
-
-
-
-
-Since Linux does not crash very often anymore, I have changed both
-values to 3600 seconds (= one hour). This caused no problems at all
-and the constant disk access has stopped. (But if my system crashes
-now, there will be more broken files, of course.)
-
-
-
-
-
-!RedHat 4.1: In /etc/inittab, change the update call to:
-
-
-
-
-
-ud::once:/sbin/update -s 3600 -f 3600
-
-
-
-
-
-
-
-Suse 4.4.1: update is called in /sbin/init.d/boot.
-
-
-
-
-
-Slackware: update is called in /etc/rc.d/rc.S.
-
-
-
-
-
-See man update for details.
-
-
-
-
-
-
-
-!!4.3 The syslogd daemon
-
-
-
-
-
-
-The syslogd daemon is responsible for the various Linux
-system log files that are found in the
-/var/log/ directory. By default syslogd will
-sync the log file each time after logging a system message.
-
-
-
-
-
-You can turn that off by preceding the filename with a dash
-in /etc/syslog.conf. Here's an example as found in
-my system's syslog.conf:
-
-
-
-
-
-# Log anything (except mail) of level info or higher.
-# Don't log private authentication messages!
-*.info;mail.none;authpriv.none -/var/log/messages
-
-
-
-
-
-
-
-This again means that if the system crashes, the message that
-reported the problem may not have been stored to disk. Dilemma...
-
-
-
-
-
-
-
-!!4.4 The init command
-
-
-
-
-
-
-During the bootup, the initial processes and daemons will be
-started using the init command. This command (yet again)
-calls sync before each process it creates.
-
-
-
-
-
-You can change this by removing the sync() call in the
-source code and recompiling the command.
-
-
-
-
-
-To avoid problems with lost file buffers, you should add a
-call to sync in your system's
-/etc/rc.d/init.d/halt script, right before the script
-unmounts the file systems.
-
-
-
-
-
-
-
-!!4.5 The swap partition
-
-
-
-
-
-
-The Linux swap partition is used to increase the physical ram space
-with virtual memory. This again is a possible reason for harddisk
-access. If your laptop already has a lot of ram or if
-the applications that you use are quite simple
-(think of vi), you might want to consider turning it off.
-
-
-
-
-
-This of course depends on what you plan to do. 4 to 8 megs are not
-enough, you must use a swap partition then. With 8 to 16 megs,
-text console applications will work fine and if you can avoid
-using a lot of multitasking features, you can safely disable
-swap. The X-Windows enviroment requires a lot of ram and you
-should not use it without a swap partition unless you really
-have a lot more than 16 megs.
-
-
-
-
-
-(Sidenote: My laptop with 16 megs and disabled swap partition can run
-an emacs session, four bash shells and compile a
-kernel without running out of memory. That's enough for me.)
-
-
-
-
-
-If you already have installed a swap partition, you can disable
-it by preceding the swapon
-command that is called in /etc/rc.d/rc.sysinit with
-a hash mark. If you don't want to make it a permanent move, let
-the system ask during boot if you want to use the swap
-partition. In /etc/rc.d/rc.sysinit (!RedHat 4.1) or
-/sbin/init.d/boot (Suse 4.4.1):
-
-
-
-
-
-echo "Should the system use swap?"
-echo " : No."
-echo " 1: Yes."
-/bin/echo "Your choice: \c"
-read SWAPCHOICE
-case "$SWAPCHOICE" in
-)
-# Do nothing.
-echo "(Swap partitions disabled)"
-;;
-*)
-# Start up swapping.
-echo "Activating swap partitions"
-swapon -a
-esac
-
-
-
-
-
-
-
-Then you can use the swap partition while on ac power and drop
-it while on battery.
-
-
-
-
-
-
-
-!!4.6 The apache httpd webserver daemon
-
-
-
-
-
-
-I am using my laptop to develop and test cgi scipts for
-websites, that is why I am running a local webserver on
-it. The standard configuration is a bit too much if all you
-want to do is just test a script or check a page from time
-to time.
-
-
-
-
-
-In httpd.conf, just change the values of
-!MinSpareServers and !StartServers to 1. This
-will be enough for a local test site.
-
-
-
-
-
-If you wish to turn off the webserver's logging, you must
-recompile the httpd daemon. Read the documentation for
-details.
-
-
-
-
-
-Grant Taylor recompiled apache's logging and found
-that this ``didn't make it stop churning the disk. So I used
-another, IMHO better, solution: I configured apache to run
-from inetd instead of standalone.'' Read man inetd for
-details.
-
-
-
-
-
-
-
-!! 4.7 The XFree86 package
-
-
-
-
-
-
-Configuring XFree86 for laptops is a story of its own. And
-yet again, I have
-to refer you to the Linux Laptop page where you
-will find a lot of help on this.
-
-
-
-
-
-X's console blanking only turns the screen black, but does
-not turn it off. As mentioned in the
-sidenote about console blanking,
-you can use xset's dpms option to change this.
-However, this feature depends on your laptop's
-graphics chipset and bios.
-
-
-
-
-
-Grant Taylor uses the following setup to send his laptop to
-sleep with the help of apmd and the screensaver:
-
-
-
-
-
-
-
-
-# Run xscreensaver with APM program
-xscreensaver -timeout 5 \
--xrm xscreensaver.programs:apm_standby \
--xrm xscreensaver.colorPrograms:apm_standby &
-
-
-
-
-
-
-
-Where ``apm_standby is a suid perl script that allows only
-certain people to run apm -S.''
-
-
-
-
-
-
-
-!!4.8 The emacs editor
-
-
-
-
-
-
-Ok, emacs is not an editor, but a way of life. Here's
-a tip from Florent Chabaud: ``If you use emacs, perhaps
-you have noticed that the editor makes some automatic saves.
-This is of course useful and should ''not'' be disabled, but
-the default parameters can be adjusted to a laptop use.
-
-
-
-
-
-I have put in the file
-/usr/share/emacs/site-lisp/site-start.el
-the two following lines:
-
-
-
-
-
-
-
-
-(setq auto-save-interval 2500)
-(setq auto-save-timeout nil)
-
-
-
-
-
-
-
-This disables auto-saving based on time, and makes the
-auto-saving be done every 2500 keyboard actions. Of course
-if you are typing a text this last parameter should be reduced,
-but for programming it is sufficient. Since every action
-(up, down, left, backspace, paste, etc...) is counted, 2500
-actions are reached very rapidly.''
-
-
-
-
-
-
-
-
-
-
-!!4.9 How to find more ways to optimize
-
-
-
-
-
-
-If your Linux system still seems to access the harddisk too
-often, you can find out what is going on inside by using
-the ps ax command. This will show all running processes
-and their full name, sometimes it also reveals the command
-line arguments of each process.
-
-
-
-
-
-Now read the man page of each process to find out what
-it does and how to change its behaviour. With this
-method, you will most likely find the process that is
-responsible. You may also find strace helpful.
-
-
-
-
-
-Please send me an email if you found something new.
-
-
-
-
-
-
-----
-
-!!5. Appendix
-
-
-
-
-
-
-
-!! 5.1 A message to Linux distributors
-
-
-
-
-
-
-If you happen to be a Linux distributor, thank you for reading
-all this. Laptops are becoming more and more popular, but still
-most Linux distributions are not very well prepared for portable
-computing. Please make this document obsolete and change this for
-your distribution.
-
-
-
-
-
-
-
-
-*The installation routine should include a configuration, optimized
-for laptops. The ``mimimal install'' is often not lean
-enough. There are a lot of things that a laptop user does not
-need on the road. Just a few examples. There is no need for
-three different versions of
-vi (as found in Suse Linux). Most portable systems do not need
-printing support (they will never be connected to a
-printer, printing is usually done with the desktop system at
-home). Quite a few laptops do not need any network support at
-all.
-
-
-
-
-
-
-*
-
-*Don't forget to describe laptop-specific installation
-problems, e. g. how to install your distribution without
-a cd-rom drive or how to setup the plip network driver.
-
-
-
-
-
-
-*
-
-*Add better power management and seamless pcmcia support to your
-distribution. Add a precompiled kernel and an alternative set of
-pcmcia drivers with apm support that the user can install on
-demand. Include a precompiled apmd package with your
-distribution.
-
-
-
-
-
-
-*
-
-*Add support for dynamically switching network configurations. Most
-Linux laptops travel between locations with different
-network settings (e. g. the network at home, the network at
-the office and the network at the university) and have
-to change the network id very often. Changing a Linux system's
-network id is a pain with most distributions.
-
-
-
-
-
-
-*
-
-
-
-Please mail me if your distribution is optimized for portable
-computing and what kind of features you added for that. Future
-versions of this HOWTO will include a section where you can
-advertise your distribution's laptop features.
-
-
-
-
-
-
-
-!! 5.2 Credits
-
-
-
-
-
-
-
-
-
-*The information about battery technology is mostly based
-on the article ``Stromkonserve''
-by Michael Reiter, published in ``c't Magazin fuer
-Computertechnik'' (Heise Verlag Hannover, Germany), edition
-10/96, page 204. Used by permission. Visit their website at
-
-http://www.heise.de/.
-
-
-
-
-
-
-*
-
-*The following people contributed to this document:
-
-
-
-
-
-
-
-Frithjof Anders <anders@goethe.ucdavis.edu>
-David Bateman <dbateman@ee.uts.edu.au>
-Florent Chabaud <chabaud@celar.fr>
-Markus Gutschke <gutschk@uni-muenster.de>
-Kenneth E. Harker <kharker@cs.utexas.edu>
-Bjoern Kriews <bkr@rrz.uni-hamburg.de>
-R. Manmatha <manmatha@bendigo.cs.umass.edu>
-Juergen Rink <jr@ct.heise.de>
-Grant Taylor <gtaylor@picante.com>
-James Youngman <JYoungman@vggas.com>
-
-
-
-
-
-
-*
-
-
-
-
-
-!!5.3 About this document
-
-
-
-
-
-
-This text mentions batteries 53 times.
-
-
-
-
-
-The current version of this and many other HOWTOs,
-most of them a lot more useful than this one,
-can be found at the main Linux documentation site
-
-http://sunsite.unc.edu/mdw/linux.html or at
-one of its many mirror sites.
-
-
-
-
-
-Most of this text was written during my trips between Hamburg
-and Hannover on German rail. (The new ice-2 coaches have
-power outlets for laptops, yeah!).
-
-
-
-
-
-And now hum along with me: ``...on the road again..
.''
-
-
-
-
-
-
-----
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