laptops: move laptop-mode.txt to Documentation/laptops/

Move laptop-mode.txt into the laptops/ sub-directory to consolidate
laptop doc files there.

Update references to the file's location.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 950 insertions, 0 deletions

diff --git a/Documentation/laptops/laptop-mode.txt b/Documentation/laptops/laptop-mode.txt
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--- /dev/null
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+How to conserve battery power using laptop-mode
+-----------------------------------------------
+
+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 significant
+power savings.
+
+Contents
+--------
+
+* Introduction
+* Installation
+* Caveats
+* The Details
+* Tips & Tricks
+* Control script
+* ACPI integration
+* Monitoring tool
+
+
+Installation
+------------
+
+To use laptop mode, you don't need to set any kernel configuration options
+or anything. Simply install all the files included in this document, and
+laptop mode will automatically be started when you're on battery. For
+your 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 is
+located 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 for
+laptops that don't have ACPI. On those laptops, you need to start laptop
+mode manually. To start laptop mode, run "laptop_mode start", and to
+stop it, run "laptop_mode stop". (Note: The laptop mode tools package now
+has 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 10
+  minutes of work. If you cannot afford this, don't use it! The supplied ACPI
+  scripts 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 spindown
+  cycles, 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 you
+  don't need to.
+
+* If you mount some of your ext3/reiserfs filesystems with the -n option, then
+  the control script will not be able to remount them correctly. You must set
+  DO_REMOUNTS=0 in the control script, otherwise it will remount them with the
+  wrong 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, then
+  the 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 access
+  times to determine whether a folder contains new mail. If you use mutt and
+  experience this, you must disable the noatime remounting by setting the option
+  DO_REMOUNT_NOATIME to 0 in the configuration file.
+
+
+The Details
+-----------
+
+Laptop mode is controlled by the knob /proc/sys/vm/laptop_mode. This knob is
+present for all kernels that have the laptop mode patch, regardless of any
+configuration options. When the knob is set, any physical disk I/O (that might
+have caused the hard disk to spin up) causes Linux to flush all dirty blocks. The
+result of this is that after a disk has spun down, it will not be spun up
+anymore to write dirty blocks, because those blocks had already been written
+immediately after the most recent read operation. The value of the laptop_mode
+knob determines the time between the occurrence of disk I/O and when the flush
+is triggered. A sensible value for the knob is 5 seconds. Setting the knob to
+0 disables laptop mode.
+
+To increase the effectiveness of the laptop_mode strategy, the laptop_mode
+control script increases dirty_expire_centisecs and dirty_writeback_centisecs in
+/proc/sys/vm to about 10 minutes (by default), which means that pages that are
+dirtied are not forced to be written to disk as often. The control script also
+changes the dirty background ratio, so that background writeback of dirty pages
+is not done anymore. Combined with a higher commit value (also 10 minutes) for
+ext3 or ReiserFS filesystems (also done automatically by the control script),
+this results in concentration of disk activity in a small time interval which
+occurs only once every 10 minutes, or whenever the disk is forced to spin up by
+a cache miss. The disk can then be spun down in the periods of inactivity.
+
+If you want to find out which process caused the disk to spin up, you can
+gather information by setting the flag /proc/sys/vm/block_dump. When this flag
+is set, Linux reports all disk read and write operations that take place, and
+all block dirtyings done to files. This makes it possible to debug why a disk
+needs to spin up, and to increase battery life even more. The output of
+block_dump is written to the kernel output, and it can be retrieved using
+"dmesg". When you use block_dump and your kernel logging level also includes
+kernel debugging messages, you probably want to turn off klogd, otherwise
+the output of block_dump will be logged, causing disk activity that is not
+normally there.
+
+
+Configuration
+-------------
+
+The laptop mode configuration file is located in /etc/default/laptop-mode on
+Debian-based systems, or in /etc/sysconfig/laptop-mode on other systems. It
+contains the following options:
+
+MAX_AGE:
+
+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 while you're in laptop mode.
+
+MINIMUM_BATTERY_MINUTES:
+
+Automatically disable laptop mode if the remaining number of minutes of
+battery 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 mode
+is active (BATT_HD) and when it is not active (AC_HD). The defaults are
+20 seconds (value 4) for BATT_HD  and 2 hours (value 244) for AC_HD. The
+possible 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 large
+readahead can prevent disk accesses for things like executable pages (which are
+loaded on demand while the application executes) and sequentially accessed data
+(MP3s).
+
+DO_REMOUNTS:
+
+The control script automatically remounts any mounted journaled filesystems
+with appropriate commit interval options. When this option is set to 0, this
+feature 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 require
+access time recording.
+
+DIRTY_RATIO:
+
+The percentage of memory that is allowed to contain "dirty" or unsaved data
+before a writeback is forced, while laptop mode is active. Corresponds to
+the /proc/sys/vm/dirty_ratio sysctl.
+
+DIRTY_BACKGROUND_RATIO:
+
+The percentage of memory that is allowed to contain "dirty" or unsaved data
+after a forced writeback is done due to an exceeding of DIRTY_RATIO. Set
+this nice and low. This corresponds to the /proc/sys/vm/dirty_background_ratio
+sysctl.
+
+Note that the behaviour of dirty_background_ratio is quite different
+when laptop mode is active and when it isn't. When laptop mode is inactive,
+dirty_background_ratio is the threshold percentage at which background writeouts
+start taking place. When laptop mode is active, however, background writeouts
+are disabled, and the dirty_background_ratio only determines how much writeback
+is done when dirty_ratio is reached.
+
+DO_CPU:
+
+Enable CPU frequency scaling when in laptop mode. (Requires CPUFreq to be setup.
+See Documentation/cpu-freq/user-guide.txt for more info. Disabled by default.)
+
+CPU_MAXFREQ:
+
+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.
+
+
+Tips & Tricks
+-------------
+
+* Bartek Kania reports getting up to 50 minutes of extra battery life (on top
+  of 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 readahead
+  to 8MB (READAHEAD=16384). Effectively, the disk will read a complete MP3 at
+  once, and will then spin down while the MP3 is playing. (Thanks to Bartek
+  Kania.)
+
+* Drew Scott Daniels observed: "I don't know why, but when I decrease the number
+  of colours that my display uses it consumes less battery power. I've seen
+  this on powerbooks too. I hope that this is a piece of information that
+  might be useful to the Laptop Mode patch or it's users."
+
+* In syslog.conf, you can prefix entries with a dash ``-'' to omit syncing the
+  file after every logging. When you're using laptop-mode and your disk doesn't
+  spin 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-mode
+  from doing its thing.
+
+* If you're worried about your data, you might want to consider using a USB
+  memory stick or something like that as a "working area". (Be aware though
+  that flash memory can only handle a limited number of writes, and overuse
+  may wear out your memory stick pretty quickly. Do _not_ use journalling
+  filesystems on flash memory sticks.)
+
+
+Configuration file for control and ACPI battery scripts
+-------------------------------------------------------
+
+This allows the tunables to be changed for the scripts via an external
+configuration 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 BEGIN-------------------------------------------
+# 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 pdflush 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/cpu-freq/user-guide.txt 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
+
+--------------------CONFIG FILE END---------------------------------------------
+
+
+Control script
+--------------
+
+Please note that this control script works for the Linux 2.4 and 2.6 series (thanks
+to Kiko Piris).
+
+--------------------CONTROL SCRIPT BEGIN----------------------------------------
+#!/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 config
+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
+
+# 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=${MAX_AGE:-'600'}
+
+# Read-ahead, in kilobytes
+READAHEAD=${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 writeback
+DIRTY_RATIO=${DIRTY_RATIO:-'40'}
+
+# cpu frequency scaling
+# See Documentation/cpu-freq/user-guide.txt for more info
+DO_CPU=${CPU_MANAGE:-'0'}
+CPU_MAXFREQ=${CPU_MAXFREQ:-'slowest'}
+
+#
+# Allowed dirty background ratio, in percent.  Once DIRTY_RATIO has been
+# exceeded, the kernel will wake pdflush which will then reduce the amount
+# of dirty memory to dirty_background_ratio.  Set this nice and low, so once
+# some writeout has commenced, we do a lot of it.
+#
+DIRTY_BACKGROUND_RATIO=${DIRTY_BACKGROUND_RATIO:-'5'}
+
+# kernel default dirty buffer age
+DEF_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
+                ;;
+esac
+
+if [ ! -e /proc/sys/vm/laptop_mode ] ; then
+        echo "Kernel is not patched with laptop_mode patch." >&2
+        exit 1
+fi
+
+if [ ! -w /proc/sys/vm/laptop_mode ] ; then
+        echo "You do not have enough privileges to enable laptop_mode." >&2
+        exit 1
+fi
+
+# 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"
+fi
+
+case "$1" in
+        start)
+                AGE=$((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
+                ;;
+
+esac
+
+exit 0
+--------------------CONTROL SCRIPT END------------------------------------------
+
+
+ACPI integration
+----------------
+
+Dax Kelson submitted this so that the ACPI acpid daemon will
+kick off the laptop_mode script and run hdparm. The part that
+automatically disables laptop mode when the battery is low was
+written by Jan Topinski.
+
+-----------------/etc/acpi/events/ac_adapter BEGIN------------------------------
+event=ac_adapter
+action=/etc/acpi/actions/ac.sh %e
+----------------/etc/acpi/events/ac_adapter END---------------------------------
+
+
+-----------------/etc/acpi/events/battery BEGIN---------------------------------
+event=battery.*
+action=/etc/acpi/actions/battery.sh %e
+----------------/etc/acpi/events/battery END------------------------------------
+
+
+----------------/etc/acpi/actions/ac.sh BEGIN-----------------------------------
+#!/bin/bash
+
+# ac on/offline event handler
+
+status=`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/ac.sh END--------------------------
+
+
+---------------------------/etc/acpi/actions/battery.sh BEGIN-------------------
+#! /bin/bash
+
+# Automatically disable laptop mode when the battery almost runs out.
+
+BATT_INFO=/proc/acpi/battery/$2/state
+
+if [[ -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
+   fi
+fi
+---------------------------/etc/acpi/actions/battery.sh END--------------------
+
+
+Monitoring tool
+---------------
+
+Bartek Kania submitted this, it can be used to measure how much time your disk
+spends spun up/down.
+
+---------------------------dslm.c BEGIN-----------------------------------------
+/*
+ * Simple Disk Sleep Monitor
+ *  by Bartek Kania
+ * Licenced under the GPL
+ */
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <time.h>
+#include <string.h>
+#include <signal.h>
+#include <sys/ioctl.h>
+#include <linux/hdreg.h>
+
+#ifdef DEBUG
+#define D(x) x
+#else
+#define D(x)
+#endif
+
+int endit = 0;
+
+/* Check if the disk is in powersave-mode
+ * Most of the code is stolen from hdparm.
+ * 1 = active, 0 = standby/sleep, -1 = unknown */
+int check_powermode(int fd)
+{
+    unsigned char args[4] = {WIN_CHECKPOWERMODE1,0,0,0};
+    int state;
+
+    if (ioctl(fd, HDIO_DRIVE_CMD, &args)
+        && (args[0] = WIN_CHECKPOWERMODE2) /* try again with 0x98 */
+        && ioctl(fd, HDIO_DRIVE_CMD, &args)) {
+        if (errno != EIO || args[0] != 0 || args[1] != 0) {
+            state = -1; /* "unknown"; */
+        } else
+            state = 0; /* "sleeping"; */
+    } else {
+        state = (args[2] == 255) ? 1 : 0;
+    }
+    D(printf(" drive state is:  %d\n", state));
+
+    return state;
+}
+
+char *state_name(int i)
+{
+    if (i == -1) return "unknown";
+    if (i == 0) return "sleeping";
+    if (i == 1) return "active";
+
+    return "internal error";
+}
+
+char *myctime(time_t time)
+{
+    char *ts = ctime(&time);
+    ts[strlen(ts) - 1] = 0;
+
+    return ts;
+}
+
+void measure(int fd)
+{
+    time_t start_time;
+    int last_state;
+    time_t last_time;
+    int curr_state;
+    time_t curr_time = 0;
+    time_t time_diff;
+    time_t active_time = 0;
+    time_t sleep_time = 0;
+    time_t unknown_time = 0;
+    time_t total_time = 0;
+    int changes = 0;
+    float tmp;
+
+    printf("Starting measurements\n");
+
+    last_state = check_powermode(fd);
+    start_time = last_time = time(0);
+    printf("  System is in state %s\n\n", state_name(last_state));
+
+    while(!endit) {
+        sleep(1);
+        curr_state = check_powermode(fd);
+
+        if (curr_state != last_state || endit) {
+            changes++;
+            curr_time = time(0);
+            time_diff = curr_time - last_time;
+
+            if (last_state == 1) active_time += time_diff;
+            else if (last_state == 0) sleep_time += time_diff;
+            else unknown_time += time_diff;
+
+            last_state = curr_state;
+            last_time = curr_time;
+
+            printf("%s: State-change to %s\n", myctime(curr_time),
+                   state_name(curr_state));
+        }
+    }
+    changes--; /* Compensate for SIGINT */
+
+    total_time = time(0) - start_time;
+    printf("\nTotal running time:  %lus\n", curr_time - start_time);
+    printf(" State changed %d times\n", changes);
+
+    tmp = (float)sleep_time / (float)total_time * 100;
+    printf(" Time in sleep state:   %lus (%.2f%%)\n", sleep_time, tmp);
+    tmp = (float)active_time / (float)total_time * 100;
+    printf(" Time in active state:  %lus (%.2f%%)\n", active_time, tmp);
+    tmp = (float)unknown_time / (float)total_time * 100;
+    printf(" Time in unknown state: %lus (%.2f%%)\n", unknown_time, tmp);
+}
+
+void ender(int s)
+{
+    endit = 1;
+}
+
+void usage()
+{
+    puts("usage: dslm [-w <time>] <disk>");
+    exit(0);
+}
+
+int main(int argc, char **argv)
+{
+    int fd;
+    char *disk = 0;
+    int settle_time = 60;
+
+    /* Parse the simple command-line */
+    if (argc == 2)
+        disk = argv[1];
+    else if (argc == 4) {
+        settle_time = atoi(argv[2]);
+        disk = argv[3];
+    } else
+        usage();
+
+    if (!(fd = open(disk, O_RDONLY|O_NONBLOCK))) {
+        printf("Can't open %s, because: %s\n", disk, strerror(errno));
+        exit(-1);
+    }
+
+    if (settle_time) {
+        printf("Waiting %d seconds for the system to settle down to "
+               "'normal'\n", settle_time);
+        sleep(settle_time);
+    } else
+        puts("Not waiting for system to settle down");
+
+    signal(SIGINT, ender);
+
+    measure(fd);
+
+    close(fd);
+
+    return 0;
+}
+---------------------------dslm.c END-------------------------------------------