How to conserve battery power using laptop-mode — The Linux Kernel documentation (2024)

Document Author: Bart Samwel (bart@samwel.tk)

Date created: January 2, 2004

Last modified: December 06, 2004

Introduction¶

Laptop mode is used to minimize the time that the hard disk needs to be spun up,to conserve battery power on laptops. It has been reported to cause significantpower savings.

Installation¶

To use laptop mode, you don’t need to set any kernel configuration optionsor anything. Simply install all the files included in this document, andlaptop mode will automatically be started when you’re on battery. Foryour convenience, a tarball containing an installer can be downloaded at:

http://www.samwel.tk/laptop_mode/laptop_mode/

To configure laptop mode, you need to edit the configuration file, which islocated in /etc/default/laptop-mode on Debian-based systems, or in/etc/sysconfig/laptop-mode on other systems.

Unfortunately, automatic enabling of laptop mode does not work forlaptops that don’t have ACPI. On those laptops, you need to start laptopmode manually. To start laptop mode, run “laptop_mode start”, and tostop it, run “laptop_mode stop”. (Note: The laptop mode tools package nowhas experimental support for APM, you might want to try that first.)

Caveats¶

The downside of laptop mode is that you have a chance of losing up to 10minutes of work. If you cannot afford this, don’t use it! The supplied ACPIscripts automatically turn off laptop mode when the battery almost runs out,so that you won’t lose any data at the end of your battery life.
Most desktop hard drives have a very limited lifetime measured in spindowncycles, typically about 50.000 times (it’s usually listed on the spec sheet).Check your drive’s rating, and don’t wear down your drive’s lifetime if youdon’t need to.
If you mount some of your ext3/reiserfs filesystems with the -n option, thenthe control script will not be able to remount them correctly. You must setDO_REMOUNTS=0 in the control script, otherwise it will remount them with thewrong options -- or it will fail because it cannot write to /etc/mtab.
If you have your filesystems listed as type “auto” in fstab, like I did, thenthe control script will not recognize them as filesystems that need remounting.You must list the filesystems with their true type instead.
It has been reported that some versions of the mutt mail client use file accesstimes to determine whether a folder contains new mail. If you use mutt andexperience this, you must disable the noatime remounting by setting the optionDO_REMOUNT_NOATIME to 0 in the configuration file.

The Details¶

Laptop mode is controlled by the knob /proc/sys/vm/laptop_mode. This knob ispresent for all kernels that have the laptop mode patch, regardless of anyconfiguration options. When the knob is set, any physical disk I/O (that mighthave caused the hard disk to spin up) causes Linux to flush all dirty blocks. Theresult of this is that after a disk has spun down, it will not be spun upanymore to write dirty blocks, because those blocks had already been writtenimmediately after the most recent read operation. The value of the laptop_modeknob determines the time between the occurrence of disk I/O and when the flushis triggered. A sensible value for the knob is 5 seconds. Setting the knob to0 disables laptop mode.

To increase the effectiveness of the laptop_mode strategy, the laptop_modecontrol script increases dirty_expire_centisecs and dirty_writeback_centisecs in/proc/sys/vm to about 10 minutes (by default), which means that pages that aredirtied are not forced to be written to disk as often. The control script alsochanges the dirty background ratio, so that background writeback of dirty pagesis not done anymore. Combined with a higher commit value (also 10 minutes) forext3 or ReiserFS filesystems (also done automatically by the control script),this results in concentration of disk activity in a small time interval whichoccurs only once every 10 minutes, or whenever the disk is forced to spin up bya cache miss. The disk can then be spun down in the periods of inactivity.

Configuration¶

The laptop mode configuration file is located in /etc/default/laptop-mode onDebian-based systems, or in /etc/sysconfig/laptop-mode on other systems. Itcontains the following options:

MAX_AGE:

Maximum time, in seconds, of hard drive spindown time that you arecomfortable with. Worst case, it’s possible that you could lose thisamount of work if your battery fails while you’re in laptop mode.

MINIMUM_BATTERY_MINUTES:

Automatically disable laptop mode if the remaining number of minutes ofbattery power is less than this value. Default is 10 minutes.

AC_HD/BATT_HD:

The idle timeout that should be set on your hard drive when laptop modeis active (BATT_HD) and when it is not active (AC_HD). The defaults are20 seconds (value 4) for BATT_HD and 2 hours (value 244) for AC_HD. Thepossible values are those listed in the manual page for “hdparm” for the“-S” option.

HD:

The devices for which the spindown timeout should be adjusted by laptop mode.Default is /dev/hda. If you specify multiple devices, separate them by a space.

READAHEAD:

Disk readahead, in 512-byte sectors, while laptop mode is active. A largereadahead can prevent disk accesses for things like executable pages (which areloaded on demand while the application executes) and sequentially accessed data(MP3s).

DO_REMOUNTS:

The control script automatically remounts any mounted journaled filesystemswith appropriate commit interval options. When this option is set to 0, thisfeature is disabled.

DO_REMOUNT_NOATIME:

When remounting, should the filesystems be remounted with the noatime option?Normally, this is set to “1” (enabled), but there may be programs that requireaccess time recording.

DIRTY_RATIO:

The percentage of memory that is allowed to contain “dirty” or unsaved databefore a writeback is forced, while laptop mode is active. Corresponds tothe /proc/sys/vm/dirty_ratio sysctl.

DIRTY_BACKGROUND_RATIO:

Tips & Tricks¶

Bartek Kania reports getting up to 50 minutes of extra battery life (on topof his regular 3 to 3.5 hours) using a spindown time of 5 seconds (BATT_HD=1).
You can spin down the disk while playing MP3, by setting disk readaheadto 8MB (READAHEAD=16384). Effectively, the disk will read a complete MP3 atonce, and will then spin down while the MP3 is playing. (Thanks to BartekKania.)
Drew Scott Daniels observed: “I don’t know why, but when I decrease the numberof colours that my display uses it consumes less battery power. I’ve seenthis on powerbooks too. I hope that this is a piece of information thatmight be useful to the Laptop Mode patch or its users.”
In syslog.conf, you can prefix entries with a dash - to omit syncing thefile after every logging. When you’re using laptop-mode and your disk doesn’tspin down, this is a likely culprit.
Richard Atterer observed that laptop mode does not work well with noflushd(http://noflushd.sourceforge.net/), it seems that noflushd prevents laptop-modefrom doing its thing.
If you’re worried about your data, you might want to consider using a USBmemory stick or something like that as a “working area”. (Be aware thoughthat flash memory can only handle a limited number of writes, and overusemay wear out your memory stick pretty quickly. Do _not_ use journallingfilesystems on flash memory sticks.)

Configuration file for control and ACPI battery scripts¶

This allows the tunables to be changed for the scripts via an externalconfiguration file

It should be installed as /etc/default/laptop-mode on Debian, and as/etc/sysconfig/laptop-mode on Red Hat, SUSE, Mandrake, and other work-alikes.

Config file:

# Maximum time, in seconds, of hard drive spindown time that you are# comfortable with. Worst case, it's possible that you could lose this# amount of work if your battery fails you while in laptop mode.#MAX_AGE=600# Automatically disable laptop mode when the number of minutes of battery# that you have left goes below this threshold.MINIMUM_BATTERY_MINUTES=10# Read-ahead, in 512-byte sectors. You can spin down the disk while playing MP3/OGG# by setting the disk readahead to 8MB (READAHEAD=16384). Effectively, the disk# will read a complete MP3 at once, and will then spin down while the MP3/OGG is# playing.#READAHEAD=4096# Shall we remount journaled fs. with appropriate commit interval? (1=yes)#DO_REMOUNTS=1# And shall we add the "noatime" option to that as well? (1=yes)#DO_REMOUNT_NOATIME=1# Dirty synchronous ratio. At this percentage of dirty pages the process# which# calls write() does its own writeback#DIRTY_RATIO=40## Allowed dirty background ratio, in percent. Once DIRTY_RATIO has been# exceeded, the kernel will wake flusher threads which will then reduce the# amount of dirty memory to dirty_background_ratio. Set this nice and low,# so once some writeout has commenced, we do a lot of it.##DIRTY_BACKGROUND_RATIO=5# kernel default dirty buffer age#DEF_AGE=30#DEF_UPDATE=5#DEF_DIRTY_BACKGROUND_RATIO=10#DEF_DIRTY_RATIO=40#DEF_XFS_AGE_BUFFER=15#DEF_XFS_SYNC_INTERVAL=30#DEF_XFS_BUFD_INTERVAL=1# This must be adjusted manually to the value of HZ in the running kernel# on 2.4, until the XFS people change their 2.4 external interfaces to work in# centisecs. This can be automated, but it's a work in progress that still# needs# some fixes. On 2.6 kernels, XFS uses USER_HZ instead of HZ for# external interfaces, and that is currently always set to 100. So you don't# need to change this on 2.6.#XFS_HZ=100# Should the maximum CPU frequency be adjusted down while on battery?# Requires CPUFreq to be setup.# See Documentation/admin-guide/pm/cpufreq.rst for more info#DO_CPU=0# When on battery what is the maximum CPU speed that the system should# use? Legal values are "slowest" for the slowest speed that your# CPU is able to operate at, or a value listed in:# /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies# Only applicable if DO_CPU=1.#CPU_MAXFREQ=slowest# Idle timeout for your hard drive (man hdparm for valid values, -S option)# Default is 2 hours on AC (AC_HD=244) and 20 seconds for battery (BATT_HD=4).#AC_HD=244#BATT_HD=4# The drives for which to adjust the idle timeout. Separate them by a space,# e.g. HD="/dev/hda /dev/hdb".#HD="/dev/hda"# Set the spindown timeout on a hard drive?#DO_HD=1

Control script¶

Please note that this control script works for the Linux 2.4 and 2.6 series (thanksto Kiko Piris).

Control script:

#!/bin/bash# start or stop laptop_mode, best run by a power management daemon when# ac gets connected/disconnected from a laptop## install as /sbin/laptop_mode## Contributors to this script: Kiko Piris# Bart Samwel# Micha Feigin# Andrew Morton# Herve Eychenne# Dax Kelson## Original Linux 2.4 version by: Jens Axboe############################################################################## Source configif [ -f /etc/default/laptop-mode ] ; then # Debian . /etc/default/laptop-modeelif [ -f /etc/sysconfig/laptop-mode ] ; then # Others . /etc/sysconfig/laptop-modefi# Don't raise an error if the config file is incomplete# set defaults instead:# Maximum time, in seconds, of hard drive spindown time that you are# comfortable with. Worst case, it's possible that you could lose this# amount of work if your battery fails you while in laptop mode.MAX_AGE=${MAX_AGE:-'600'}# Read-ahead, in kilobytesREADAHEAD=${READAHEAD:-'4096'}# Shall we remount journaled fs. with appropriate commit interval? (1=yes)DO_REMOUNTS=${DO_REMOUNTS:-'1'}# And shall we add the "noatime" option to that as well? (1=yes)DO_REMOUNT_NOATIME=${DO_REMOUNT_NOATIME:-'1'}# Shall we adjust the idle timeout on a hard drive?DO_HD=${DO_HD:-'1'}# Adjust idle timeout on which hard drive?HD="${HD:-'/dev/hda'}"# spindown time for HD (hdparm -S values)AC_HD=${AC_HD:-'244'}BATT_HD=${BATT_HD:-'4'}# Dirty synchronous ratio. At this percentage of dirty pages the process which# calls write() does its own writebackDIRTY_RATIO=${DIRTY_RATIO:-'40'}# cpu frequency scaling# See Documentation/admin-guide/pm/cpufreq.rst for more infoDO_CPU=${CPU_MANAGE:-'0'}CPU_MAXFREQ=${CPU_MAXFREQ:-'slowest'}## Allowed dirty background ratio, in percent. Once DIRTY_RATIO has been# exceeded, the kernel will wake flusher threads which will then reduce the# amount of dirty memory to dirty_background_ratio. Set this nice and low,# so once some writeout has commenced, we do a lot of it.#DIRTY_BACKGROUND_RATIO=${DIRTY_BACKGROUND_RATIO:-'5'}# kernel default dirty buffer ageDEF_AGE=${DEF_AGE:-'30'}DEF_UPDATE=${DEF_UPDATE:-'5'}DEF_DIRTY_BACKGROUND_RATIO=${DEF_DIRTY_BACKGROUND_RATIO:-'10'}DEF_DIRTY_RATIO=${DEF_DIRTY_RATIO:-'40'}DEF_XFS_AGE_BUFFER=${DEF_XFS_AGE_BUFFER:-'15'}DEF_XFS_SYNC_INTERVAL=${DEF_XFS_SYNC_INTERVAL:-'30'}DEF_XFS_BUFD_INTERVAL=${DEF_XFS_BUFD_INTERVAL:-'1'}# This must be adjusted manually to the value of HZ in the running kernel# on 2.4, until the XFS people change their 2.4 external interfaces to work in# centisecs. This can be automated, but it's a work in progress that still needs# some fixes. On 2.6 kernels, XFS uses USER_HZ instead of HZ for external# interfaces, and that is currently always set to 100. So you don't need to# change this on 2.6.XFS_HZ=${XFS_HZ:-'100'}#############################################################################KLEVEL="$(uname -r | { IFS='.' read a b c echo $a.$b })"case "$KLEVEL" in "2.4"|"2.6") ;; *) echo "Unhandled kernel version: $KLEVEL ('uname -r' = '$(uname -r)')" >&2 exit 1 ;;esacif [ ! -e /proc/sys/vm/laptop_mode ] ; then echo "Kernel is not patched with laptop_mode patch." >&2 exit 1fiif [ ! -w /proc/sys/vm/laptop_mode ] ; then echo "You do not have enough privileges to enable laptop_mode." >&2 exit 1fi# Remove an option (the first parameter) of the form option=<number> from# a mount options string (the rest of the parameters).parse_mount_opts () { OPT="$1" shift echo ",$*," | sed \ -e 's/,'"$OPT"'=[0-9]*,/,/g' \ -e 's/,,*/,/g' \ -e 's/^,//' \ -e 's/,$//'}# Remove an option (the first parameter) without any arguments from# a mount option string (the rest of the parameters).parse_nonumber_mount_opts () { OPT="$1" shift echo ",$*," | sed \ -e 's/,'"$OPT"',/,/g' \ -e 's/,,*/,/g' \ -e 's/^,//' \ -e 's/,$//'}# Find out the state of a yes/no option (e.g. "atime"/"noatime") in# fstab for a given filesystem, and use this state to replace the# value of the option in another mount options string. The device# is the first argument, the option name the second, and the default# value the third. The remainder is the mount options string.## Example:# parse_yesno_opts_wfstab /dev/hda1 atime atime defaults,noatime## If fstab contains, say, "rw" for this filesystem, then the result# will be "defaults,atime".parse_yesno_opts_wfstab () { L_DEV="$1" OPT="$2" DEF_OPT="$3" shift 3 L_OPTS="$*" PARSEDOPTS1="$(parse_nonumber_mount_opts $OPT $L_OPTS)" PARSEDOPTS1="$(parse_nonumber_mount_opts no$OPT $PARSEDOPTS1)" # Watch for a default atime in fstab FSTAB_OPTS="$(awk '$1 == "'$L_DEV'" { print $4 }' /etc/fstab)" if echo "$FSTAB_OPTS" | grep "$OPT" > /dev/null ; then # option specified in fstab: extract the value and use it if echo "$FSTAB_OPTS" | grep "no$OPT" > /dev/null ; then echo "$PARSEDOPTS1,no$OPT" else # no$OPT not found -- so we must have $OPT. echo "$PARSEDOPTS1,$OPT" fi else # option not specified in fstab -- choose the default. echo "$PARSEDOPTS1,$DEF_OPT" fi}# Find out the state of a numbered option (e.g. "commit=NNN") in# fstab for a given filesystem, and use this state to replace the# value of the option in another mount options string. The device# is the first argument, and the option name the second. The# remainder is the mount options string in which the replacement# must be done.## Example:# parse_mount_opts_wfstab /dev/hda1 commit defaults,commit=7## If fstab contains, say, "commit=3,rw" for this filesystem, then the# result will be "rw,commit=3".parse_mount_opts_wfstab () { L_DEV="$1" OPT="$2" shift 2 L_OPTS="$*" PARSEDOPTS1="$(parse_mount_opts $OPT $L_OPTS)" # Watch for a default commit in fstab FSTAB_OPTS="$(awk '$1 == "'$L_DEV'" { print $4 }' /etc/fstab)" if echo "$FSTAB_OPTS" | grep "$OPT=" > /dev/null ; then # option specified in fstab: extract the value, and use it echo -n "$PARSEDOPTS1,$OPT=" echo ",$FSTAB_OPTS," | sed \ -e 's/.*,'"$OPT"'=//' \ -e 's/,.*//' else # option not specified in fstab: set it to 0 echo "$PARSEDOPTS1,$OPT=0" fi}deduce_fstype () { MP="$1" # My root filesystem unfortunately has # type "unknown" in /etc/mtab. If we encounter # "unknown", we try to get the type from fstab. cat /etc/fstab | grep -v '^#' | while read FSTAB_DEV FSTAB_MP FSTAB_FST FSTAB_OPTS FSTAB_DUMP FSTAB_DUMP ; do if [ "$FSTAB_MP" = "$MP" ]; then echo $FSTAB_FST exit 0 fi done}if [ $DO_REMOUNT_NOATIME -eq 1 ] ; then NOATIME_OPT=",noatime"ficase "$1" in start) AGE=$((100*$MAX_AGE)) XFS_AGE=$(($XFS_HZ*$MAX_AGE)) echo -n "Starting laptop_mode" if [ -d /proc/sys/vm/pagebuf ] ; then # (For 2.4 and early 2.6.) # This only needs to be set, not reset -- it is only used when # laptop mode is enabled. echo $XFS_AGE > /proc/sys/vm/pagebuf/lm_flush_age echo $XFS_AGE > /proc/sys/fs/xfs/lm_sync_interval elif [ -f /proc/sys/fs/xfs/lm_age_buffer ] ; then # (A couple of early 2.6 laptop mode patches had these.) # The same goes for these. echo $XFS_AGE > /proc/sys/fs/xfs/lm_age_buffer echo $XFS_AGE > /proc/sys/fs/xfs/lm_sync_interval elif [ -f /proc/sys/fs/xfs/age_buffer ] ; then # (2.6.6) # But not for these -- they are also used in normal # operation. echo $XFS_AGE > /proc/sys/fs/xfs/age_buffer echo $XFS_AGE > /proc/sys/fs/xfs/sync_interval elif [ -f /proc/sys/fs/xfs/age_buffer_centisecs ] ; then # (2.6.7 upwards) # And not for these either. These are in centisecs, # not USER_HZ, so we have to use $AGE, not $XFS_AGE. echo $AGE > /proc/sys/fs/xfs/age_buffer_centisecs echo $AGE > /proc/sys/fs/xfs/xfssyncd_centisecs echo 3000 > /proc/sys/fs/xfs/xfsbufd_centisecs fi case "$KLEVEL" in "2.4") echo 1 > /proc/sys/vm/laptop_mode echo "30 500 0 0 $AGE $AGE 60 20 0" > /proc/sys/vm/bdflush ;; "2.6") echo 5 > /proc/sys/vm/laptop_mode echo "$AGE" > /proc/sys/vm/dirty_writeback_centisecs echo "$AGE" > /proc/sys/vm/dirty_expire_centisecs echo "$DIRTY_RATIO" > /proc/sys/vm/dirty_ratio echo "$DIRTY_BACKGROUND_RATIO" > /proc/sys/vm/dirty_background_ratio ;; esac if [ $DO_REMOUNTS -eq 1 ]; then cat /etc/mtab | while read DEV MP FST OPTS DUMP PASS ; do PARSEDOPTS="$(parse_mount_opts "$OPTS")" if [ "$FST" = 'unknown' ]; then FST=$(deduce_fstype $MP) fi case "$FST" in "ext3"|"reiserfs") PARSEDOPTS="$(parse_mount_opts commit "$OPTS")" mount $DEV -t $FST $MP -o remount,$PARSEDOPTS,commit=$MAX_AGE$NOATIME_OPT ;; "xfs") mount $DEV -t $FST $MP -o remount,$OPTS$NOATIME_OPT ;; esac if [ -b $DEV ] ; then blockdev --setra $(($READAHEAD * 2)) $DEV fi done fi if [ $DO_HD -eq 1 ] ; then for THISHD in $HD ; do /sbin/hdparm -S $BATT_HD $THISHD > /dev/null 2>&1 /sbin/hdparm -B 1 $THISHD > /dev/null 2>&1 done fi if [ $DO_CPU -eq 1 -a -e /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq ]; then if [ $CPU_MAXFREQ = 'slowest' ]; then CPU_MAXFREQ=`cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq` fi echo $CPU_MAXFREQ > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq fi echo "." ;; stop) U_AGE=$((100*$DEF_UPDATE)) B_AGE=$((100*$DEF_AGE)) echo -n "Stopping laptop_mode" echo 0 > /proc/sys/vm/laptop_mode if [ -f /proc/sys/fs/xfs/age_buffer -a ! -f /proc/sys/fs/xfs/lm_age_buffer ] ; then # These need to be restored, if there are no lm_*. echo $(($XFS_HZ*$DEF_XFS_AGE_BUFFER)) > /proc/sys/fs/xfs/age_buffer echo $(($XFS_HZ*$DEF_XFS_SYNC_INTERVAL)) > /proc/sys/fs/xfs/sync_interval elif [ -f /proc/sys/fs/xfs/age_buffer_centisecs ] ; then # These need to be restored as well. echo $((100*$DEF_XFS_AGE_BUFFER)) > /proc/sys/fs/xfs/age_buffer_centisecs echo $((100*$DEF_XFS_SYNC_INTERVAL)) > /proc/sys/fs/xfs/xfssyncd_centisecs echo $((100*$DEF_XFS_BUFD_INTERVAL)) > /proc/sys/fs/xfs/xfsbufd_centisecs fi case "$KLEVEL" in "2.4") echo "30 500 0 0 $U_AGE $B_AGE 60 20 0" > /proc/sys/vm/bdflush ;; "2.6") echo "$U_AGE" > /proc/sys/vm/dirty_writeback_centisecs echo "$B_AGE" > /proc/sys/vm/dirty_expire_centisecs echo "$DEF_DIRTY_RATIO" > /proc/sys/vm/dirty_ratio echo "$DEF_DIRTY_BACKGROUND_RATIO" > /proc/sys/vm/dirty_background_ratio ;; esac if [ $DO_REMOUNTS -eq 1 ] ; then cat /etc/mtab | while read DEV MP FST OPTS DUMP PASS ; do # Reset commit and atime options to defaults. if [ "$FST" = 'unknown' ]; then FST=$(deduce_fstype $MP) fi case "$FST" in "ext3"|"reiserfs") PARSEDOPTS="$(parse_mount_opts_wfstab $DEV commit $OPTS)" PARSEDOPTS="$(parse_yesno_opts_wfstab $DEV atime atime $PARSEDOPTS)" mount $DEV -t $FST $MP -o remount,$PARSEDOPTS ;; "xfs") PARSEDOPTS="$(parse_yesno_opts_wfstab $DEV atime atime $OPTS)" mount $DEV -t $FST $MP -o remount,$PARSEDOPTS ;; esac if [ -b $DEV ] ; then blockdev --setra 256 $DEV fi done fi if [ $DO_HD -eq 1 ] ; then for THISHD in $HD ; do /sbin/hdparm -S $AC_HD $THISHD > /dev/null 2>&1 /sbin/hdparm -B 255 $THISHD > /dev/null 2>&1 done fi if [ $DO_CPU -eq 1 -a -e /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq ]; then echo `cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq` > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq fi echo "." ;; *) echo "Usage: $0 {start|stop}" 2>&1 exit 1 ;;esacexit 0

ACPI integration¶

Dax Kelson submitted this so that the ACPI acpid daemon willkick off the laptop_mode script and run hdparm. The part thatautomatically disables laptop mode when the battery is low waswritten by Jan Topinski.

/etc/acpi/events/ac_adapter:

event=ac_adapteraction=/etc/acpi/actions/ac.sh %e

/etc/acpi/events/battery:

event=battery.*action=/etc/acpi/actions/battery.sh %e

/etc/acpi/actions/ac.sh:

#!/bin/bash# ac on/offline event handlerstatus=`awk '/^state: / { print $2 }' /proc/acpi/ac_adapter/$2/state`case $status in "on-line") /sbin/laptop_mode stop exit 0 ;; "off-line") /sbin/laptop_mode start exit 0 ;;esac

/etc/acpi/actions/battery.sh:

#! /bin/bash# Automatically disable laptop mode when the battery almost runs out.BATT_INFO=/proc/acpi/battery/$2/stateif [[ -f /proc/sys/vm/laptop_mode ]]then LM=`cat /proc/sys/vm/laptop_mode` if [[ $LM -gt 0 ]] then if [[ -f $BATT_INFO ]] then # Source the config file only now that we know we need if [ -f /etc/default/laptop-mode ] ; then # Debian . /etc/default/laptop-mode elif [ -f /etc/sysconfig/laptop-mode ] ; then # Others . /etc/sysconfig/laptop-mode fi MINIMUM_BATTERY_MINUTES=${MINIMUM_BATTERY_MINUTES:-'10'} ACTION="`cat $BATT_INFO | grep charging | cut -c 26-`" if [[ ACTION -eq "discharging" ]] then PRESENT_RATE=`cat $BATT_INFO | grep "present rate:" | sed "s/.* \([0-9][0-9]* \).*/\1/" ` REMAINING=`cat $BATT_INFO | grep "remaining capacity:" | sed "s/.* \([0-9][0-9]* \).*/\1/" ` fi if (($REMAINING * 60 / $PRESENT_RATE < $MINIMUM_BATTERY_MINUTES)) then /sbin/laptop_mode stop fi else logger -p daemon.warning "You are using laptop mode and your battery interface $BATT_INFO is missing. This may lead to loss of data when the battery runs out. Check kernel ACPI support and /proc/acpi/battery folder, and edit /etc/acpi/battery.sh to set BATT_INFO to the correct path." fi fifi

Monitoring tool¶

Bartek Kania submitted this, it can be used to measure how much time your diskspends spun up/down. See tools/laptop/dslm/dslm.c