From: Bart Samwel <bart@samwel.tk>
This patch contains the following updates to the laptop mode docs:
* Various improvements to the text, added a hint and a caveat.
* Control script changes to support XFS (in 2.4, 2.6 with lm_* sysctl
values and 2.6 without lm_* sysctl values).
* Control script changes to reset the the "atime" mount option to the
value listed in fstab when laptop mode is stopped.
* Bug fix in dslm.c.---
---
25-akpm/Documentation/laptop-mode.txt | 204 ++++++++++++++++++++++++++++++----
1 files changed, 180 insertions(+), 24 deletions(-)
diff -puN Documentation/laptop-mode.txt~laptop-mode-doc-update Documentation/laptop-mode.txt
--- 25/Documentation/laptop-mode.txt~laptop-mode-doc-update 2004-04-04 16:40:33.014162448 -0700
+++ 25-akpm/Documentation/laptop-mode.txt 2004-04-04 16:40:33.020161536 -0700
@@ -3,6 +3,7 @@ How to conserve battery power using lapt
Document Author: Bart Samwel (bart@samwel.tk)
Date created: January 2, 2004
+Last modified: April 3, 2004
Introduction
------------
@@ -40,15 +41,20 @@ The value -S 4 means 20 seconds idle tim
now only spin up when a disk cache miss occurs, or at least once every 10
minutes to write back any pending changes.
-To stop laptop_mode, remount your filesystems with regular commit intervals
-(e.g., 5 seconds), and run "laptop_mode stop".
+To stop laptop_mode, run "laptop_mode stop".
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!
+ to 10 minutes of work. If you cannot afford this, don't use it! It's
+ wise to turn OFF laptop mode when you're almost out of battery --
+ although this will make the battery run out faster, at least you'll
+ lose less work when it actually runs out. I'm still looking for someone
+ to submit instructions on how to turn off laptop mode when battery is low,
+ e.g., using ACPI events. I don't have a laptop myself, so if you do and
+ you care to contribute such instructions, please do.
* 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).
@@ -63,6 +69,14 @@ Caveats
* 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.
+* If you have XFS, make SURE that you set the XFS_HZ value in the control script
+ correctly, to the value of HZ of your running kernel. Laptop mode will not
+ work correctly if it is set too low, and you may lose data if it is set too
+ high. The reason for this problem is that XFS does not export its sysctl
+ variables in centisecs (like most other subsystems do) but in "jiffies",
+ which is an internal kernel measure. Once this is fixed things will get better.
+
+
The details
-----------
@@ -88,7 +102,11 @@ If you want to find out which process ca
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.
+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, you may want to turn off klogd, otherwise
+the output of block_dump will be logged, causing disk activity that is not
+normally there.
If 10 minutes is too much or too little downtime for you, you can configure
this downtime as follows. In the control script, set the MAX_AGE value to the
@@ -132,6 +150,10 @@ Tips & Tricks
The supplied script does this.
+* 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.
+
Control script
--------------
@@ -139,7 +161,7 @@ Control script
Please note that this control script works for the Linux 2.4 and 2.6 series.
--------------------CONTROL SCRIPT BEGIN------------------------------------------
-#!/bin/sh
+#! /bin/sh
# start or stop laptop_mode, best run by a power management daemon when
# ac gets connected/disconnected from a laptop
@@ -148,28 +170,120 @@ Please note that this control script wor
#
# Contributors to this script: Kiko Piris
# Bart Samwel
+# Micha Feigin
+# Andrew Morton
# Dax Kelson
+#
# Original Linux 2.4 version by: Jens Axboe
+# 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 's/commit=[0-9]*//g' | \
+ sed 's/.*/,&,/' | \
+ sed 's/,'"$OPT"'=[0-9]*,/,/g' | \
sed 's/,,*/,/g' | \
sed 's/^,//' | \
sed 's/,$//' | \
cat -
}
+# 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 's/.*/,&,/' | \
+ sed 's/,'"$OPT"',/,/g' | \
+ sed 's/,,*/,/g' | \
+ sed 's/^,//' | \
+ sed 's/,$//' | \
+ cat -
+}
+
+# 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
+ shift
+ OPT=$1
+ shift
+ DEF_OPT=$1
+ shift
+ L_OPTS="$*"
+ PARSEDOPTS1="$(parse_nonumber_mount_opts $OPT $L_OPTS)"
+ PARSEDOPTS1="$(parse_nonumber_mount_opts no$OPT $PARSEDOPTS1)"
+ # Watch for a default atime in fstab
+ FSTAB_OPTS="$(cat /etc/fstab | sed 's/ / /g' | grep ^\ *"$L_DEV " | awk '{ print $4 }')"
+ if [ -z "$(echo "$FSTAB_OPTS" | grep "$OPT")" ] ; then
+ # option not specified in fstab -- choose the default.
+ echo "$PARSEDOPTS1,$DEF_OPT"
+ else
+ # option specified in fstab: extract the value and use it
+ if [ -z "$(echo "$FSTAB_OPTS" | grep "no$OPT")" ] ; then
+ # no$OPT not found -- so we must have $OPT.
+ echo "$PARSEDOPTS1,$OPT"
+ else
+ echo "$PARSEDOPTS1,no$OPT"
+ fi
+ 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
+ shift
+ OPT=$1
+ shift
+ L_OPTS="$*"
+
+ PARSEDOPTS1="$(parse_mount_opts $OPT $L_OPTS)"
+ # Watch for a default commit in fstab
+ FSTAB_OPTS="$(cat /etc/fstab | sed 's/ / /g' | grep ^\ *"$L_DEV " | awk '{ print $4 }')"
+ if [ -z "$(echo "$FSTAB_OPTS" | grep "$OPT=")" ] ; then
+ # option not specified in fstab: set it to 0
+ echo "$PARSEDOPTS1,$OPT=0"
+ else
+ # option specified in fstab: extract the value, and use it
+ echo -n "$PARSEDOPTS1,$OPT="
+ echo "$FSTAB_OPTS" | \
+ sed 's/.*/,&,/' | \
+ sed 's/.*,'"$OPT"'=//' | \
+ sed 's/,.*//' | \
+ cat -
+ fi
+}
+
KLEVEL="$(uname -r | cut -c1-3)"
case "$KLEVEL" in
- "2.4")
- true
- ;;
- "2.6")
+ "2.4"|"2.6")
true
;;
*)
- echo "Unhandled kernel level: $KLEVEL ('uname -r' = '$(uname -r)')"
+ echo "Unhandled kernel version: $KLEVEL ('uname -r' = '$(uname -r)')"
exit 1
;;
esac
@@ -199,7 +313,13 @@ 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
+# This must be adjusted manually to the value of HZ in the running kernel,
+# until the XFS people change their external interfaces to work in centisecs
+# like the rest of the external world. Unfortunately this cannot be automated. :(
+XFS_HZ=1000
if [ ! -e /proc/sys/vm/laptop_mode ]; then
echo "Kernel is not patched with laptop_mode patch."
@@ -214,7 +334,25 @@ 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
+ # 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
+ # 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
+ # But not for these -- they are also used in normal
+ # operation.
+ echo $XFS_AGE > /proc/sys/fs/xfs/age_buffer
+ echo $XFS_AGE > /proc/sys/fs/xfs/sync_interval
+ fi
+
case "$KLEVEL" in
"2.4")
echo "1" > /proc/sys/vm/laptop_mode
@@ -232,26 +370,36 @@ case "$1" in
cat /etc/mtab | while read DEV MP FST OPTS DUMP PASS ; do
PARSEDOPTS="$(parse_mount_opts "$OPTS")"
case "$FST" in
- "ext3") mount $DEV -t $FST $MP -o remount,$PARSEDOPTS,commit=$MAX_AGE,noatime ;;
- "reiserfs") mount $DEV -t $FST $MP -o remount,$PARSEDOPTS,commit=$MAX_AGE,noatime ;;
- "xfs") mount $DEV -t $FST $MP -o remount,$PARSEDOPTS,commit=$MAX_AGE,noatime ;;
+ "ext3"|"reiserfs")
+ PARSEDOPTS="$(parse_mount_opts commit "$OPTS")"
+ mount $DEV -t $FST $MP -o remount,$PARSEDOPTS,commit=$MAX_AGE,noatime
+ ;;
+ "xfs")
+ mount $DEV -t $FST $MP -o remount,$OPTS,noatime
+ ;;
esac
- blockdev --setra $((READAHEAD * 2)) $DEV
done
fi
+ if [ -b $DEV ] ; then
+ blockdev --setra $(($READAHEAD * 2)) $DEV
+ fi
echo "."
;;
stop)
U_AGE=$((100*$DEF_UPDATE))
B_AGE=$((100*$DEF_AGE))
echo -n "Stopping laptop_mode"
+ echo "0" > /proc/sys/vm/laptop_mode
+ if [ -f /proc/sys/fs/xfs/age_buffer ] && [ ! -f /proc/sys/fs/xfs/lm_age_buffer ] ; then
+ # These need to be restored though, if there are no lm_*.
+ echo "$(($XFS_HZ*$DEF_XFS_AGE_BUFFER))" > /proc/sys/fs/xfs/age_buffer
+ echo "$(($XFS_HZ*$DEF_XFS_SYNC_INTERVAL))" > /proc/sys/fs/xfs/sync_interval
+ fi
case "$KLEVEL" in
"2.4")
- echo "0" > /proc/sys/vm/laptop_mode
echo "30 500 0 0 $U_AGE $B_AGE 60 20 0" > /proc/sys/vm/bdflush
;;
"2.6")
- echo "0" > /proc/sys/vm/laptop_mode
echo "$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
@@ -260,19 +408,27 @@ case "$1" in
esac
if [ $DO_REMOUNTS -eq 1 ]; then
cat /etc/mtab | while read DEV MP FST OPTS DUMP PASS ; do
- PARSEDOPTS="$(parse_mount_opts "$OPTS")"
+ # Reset commit and atime options to defaults.
case "$FST" in
- "ext3") mount $DEV -t $FST $MP -o remount,$PARSEDOPTS ;;
- "reiserfs") mount $DEV -t $FST $MP -o remount,$PARSEDOPTS ;;
- "xfs") mount $DEV -t $FST $MP -o remount,$PARSEDOPTS ;;
+ "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
- blockdev --setra 256 $DEV
done
fi
+ if [ -b $DEV ] ; then
+ blockdev --setra 256 $DEV
+ fi
echo "."
;;
*)
- echo "$0 {start|stop}"
+ echo "Usage: $0 {start|stop}"
;;
esac
@@ -379,7 +535,7 @@ int check_powermode(int fd)
} else {
state = (args[2] == 255) ? 1 : 0;
}
- D(printf(" drive state is: %s\n", state));
+ D(printf(" drive state is: %d\n", state));
return state;
}
_