diff -Naur linux-2.6.3/Documentation/laptop-mode.txt linux-2.6.3-withlaptopmode/Documentation/laptop-mode.txt --- linux-2.6.3/Documentation/laptop-mode.txt 1970-01-01 01:00:00.000000000 +0100 +++ linux-2.6.3-withlaptopmode/Documentation/laptop-mode.txt 2004-03-07 11:21:30.000000000 +0100 @@ -0,0 +1,480 @@ +How to conserve battery power using laptop-mode +----------------------------------------------- + +Document Author: Bart Samwel (bart@samwel.tk) +Date created: January 2, 2004 + +Introduction +------------ + +Laptopmode 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 +* The short story +* Caveats +* The details +* Tips & Tricks +* Control script +* ACPI integration +* Monitoring tool + + +The short story +--------------- + +If you just want to use it, run the laptop_mode control script (which is included +at the end of this document) as follows: + +# laptop_mode start + +Then set your harddisk spindown time to a relatively low value with hdparm: + +hdparm -S 4 /dev/hda + +The value -S 4 means 20 seconds idle time before spindown. Your harddisk will +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". + + +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! + +* 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. + +The details +----------- + +Laptop-mode is controlled by the flag /proc/sys/vm/laptop_mode. When this +flag is set, any physical disk read operation (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 + +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. + +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 +maximum number of seconds of disk downtime that you would like. You should +then set your filesystem's commit interval to the same value. The dirty ratio +is also configurable from the control script. + +If you don't like the idea of the control script remounting your filesystems +for you, you can change DO_REMOUNTS to 0 in the script. + +Thanks to Kiko Piris, the control script can be used to enable laptop mode on +both the Linux 2.4 and 2.6 series. + + +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 very aggressive power management (hdparm + -B1) and a spindown time of 5 seconds (hdparm -S1). + +* You can spin down the disk while playing MP3, by setting the disk readahead + to 8MB (hdparm -a 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." + + +Control script +-------------- + +Please note that this control script works for the Linux 2.4 and 2.6 series. + +--------------------CONTROL SCRIPT BEGIN------------------------------------------ +#!/bin/sh + +# 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 +# Dax Kelson +# Original Linux 2.4 version by: Jens Axboe + +parse_mount_opts () { + echo "$*" | \ + sed 's/commit=[0-9]*//g' | \ + sed 's/,,*/,/g' | \ + sed 's/^,//' | \ + sed 's/,$//' | \ + cat - +} + +KLEVEL="$(uname -r | cut -c1-3)" +case "$KLEVEL" in + "2.4") + true + ;; + "2.6") + true + ;; + *) + echo "Unhandled kernel level: $KLEVEL ('uname -r' = '$(uname -r)')" + exit 1 + ;; +esac + +# Shall we remount journaled fs. with appropiate commit interval? (1=yes) +DO_REMOUNTS=1 + +# age time, in seconds. should be put into a sysconfig file +MAX_AGE=600 + +# Allowed dirty ratio, in pct. should be put into a sysconfig file as well. +DIRTY_RATIO=40 + +# kernel default dirty buffer age +DEF_AGE=30 +DEF_UPDATE=5 +DEF_DIRTY_BACKGROUND_RATIO=10 +DEF_DIRTY_RATIO=40 + + +if [ ! -e /proc/sys/vm/laptop_mode ]; then + echo "Kernel is not patched with laptop_mode patch." + exit 1 +fi + +if [ ! -w /proc/sys/vm/laptop_mode ]; then + echo "You do not have enough privileges to enable laptop_mode." + exit 1 +fi + +case "$1" in + start) + AGE=$((100*$MAX_AGE)) + echo -n "Starting laptop_mode" + case "$KLEVEL" in + "2.4") + echo "1" > /proc/sys/vm/laptop_mode + echo "30 500 0 0 $AGE $AGE 60 20 0" > /proc/sys/vm/bdflush + ;; + "2.6") + echo "1" > /proc/sys/vm/laptop_mode + echo "$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_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 "$OPTS")" + case "$FST" in + "ext3") mount $DEV -t $FST $MP -o remount,$PARSEDOPTS,commit=$MAX_AGE ;; + "reiserfs") mount $DEV -t $FST $MP -o remount,$PARSEDOPTS,commit=$MAX_AGE ;; + "xfs") mount $DEV -t $FST $MP -o remount,$PARSEDOPTS,commit=$MAX_AGE ;; + esac + done + fi + echo "." + ;; + stop) + U_AGE=$((100*$DEF_UPDATE)) + B_AGE=$((100*$DEF_AGE)) + echo -n "Stopping laptop_mode" + case "$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 + echo "$DEF_DIRTY_BACKGROUND_RATIO" > /proc/sys/vm/dirty_background_ratio + ;; + esac + if [ $DO_REMOUNTS -eq 1 ]; then + cat /etc/mtab | while read DEV MP FST OPTS DUMP PASS ; do + PARSEDOPTS="$(parse_mount_opts "$OPTS")" + case "$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 ;; + esac + done + fi + echo "." + ;; + *) + echo "$0 {start|stop}" + ;; + +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. + +---------------------------/etc/acpi/events/ac_adapter BEGIN------------------------------------------- +event=ac_adapter +action=/etc/acpi/actions/battery.sh +---------------------------/etc/acpi/events/ac_adapter END------------------------------------------- + +---------------------------/etc/acpi/actions/battery.sh BEGIN------------------------------------------- +#!/bin/sh + +# cpu throttling +# cat /proc/acpi/processor/CPU0/throttling for more info +ACAD_THR=0 +BATT_THR=2 + +# spindown time for HD (man hdparm for valid values) +# I prefer 2 hours for acad and 20 seconds for batt +ACAD_HD=244 +BATT_HD=4 + +# ac/battery event handler + +status=`awk '/^state: / { print $2 }' /proc/acpi/ac_adapter/AC/state` + +case $status in + "on-line") + echo "Setting HD spindown to 2 hours" + /sbin/laptop-mode stop + /sbin/hdparm -S $ACAD_HD /dev/hda > /dev/null 2>&1 + /sbin/hdparm -B 255 /dev/hda > /dev/null 2>&1 + #echo -n $ACAD_CPU:$ACAD_THR > /proc/acpi/processor/CPU0/limit + exit 0 + ;; + "off-line") + echo "Setting HD spindown to 20 seconds" + /sbin/laptop-mode start + /sbin/hdparm -S $BATT_HD /dev/hda > /dev/null 2>&1 + /sbin/hdparm -B 1 /dev/hda > /dev/null 2>&1 + #echo -n $BATT_CPU:$BATT_THR > /proc/acpi/processor/CPU0/limit + exit 0 + ;; +esac +---------------------------/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 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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: %s\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