[Pm-utils] [PATCH] Proposal of auto-hibernate feature

[Christian Krause]

Hi,

Ever since I've started to use my netbook under Linux I've missed
quite much the feature of "auto-hibernate" which was available in windows:

In order to save as much battery power as possible Windows did the
following:

- after some minutes of inactivity (or closing the LID) the netbook
was suspended (to RAM)

- if the user has woken it up during the next 15 minutes, it just
resumed quickly

- otherwise it woke up automatically only to fully hibernate now

By using this process the user didn't had to think about what would
be the best option to save power or what he must do to prevent that the 
suspend mode would drain the battery, everything was done completely
automatically. Especially for only occasional usage of the netbook/laptop
it was very handy and so the time until the next recharge was quite long. 

Using hybrid-suspend was not an option, because even if it would enable
the user to resume after a complete power-loss it does not prevent draining
the battery...


I've missed that feature so much, that Ingo van Lil and I have put together
an extension to pm-utils which implements this feature.

It is implemented by only one additional file in /usr/lib/pm-utils/sleep.d/ 
and a configuration file in /etc). Both files are attached to this mail.


What's your opinion about this idea? 
Is there a chance to integrate this into the official pm-utils?
If yes, we would certainly help to achieve this! ;-)


Best regards,
Christian

/usr/lib/pm-utils/sleep.d/000auto-hibernate:

#! /bin/sh
#
# Copyright 2009 Ingo van Lil <inguin at gmx.de>
#                Christian Krause <chkr at plauener.de>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of version 2 of the GNU General Public License as
# published by the Free Software Foundation.

. "${PM_FUNCTIONS}"

# constants
# how long to wait for the main script to release the lock in seconds
LOCK_TIMEOUT=10

# defaults
RTC="/sys/class/rtc/rtc0"
TIME_TO_HIBERNATE=900

# get user configured values
source /etc/pm-utils-auto-hibernate.conf

# Is auto-hibernate enabled ?
[ "$AUTO_HIBERNATE_ENABLED" = "y" ] || exit $NA

schedule_alarm () {
	now=`cat "${RTC}/since_epoch"`
	alarm_time=$((now + TIME_TO_HIBERNATE))
	savestate auto-hibernate-alarm ${alarm_time}
	echo > "${RTC}/wakealarm"
	echo ${alarm_time} > "${RTC}/wakealarm"
}

schedule_hibernate () {
	# wait for pm-action to terminate ...
	spin_lock "${STASHNAME}.lock" ${LOCK_TIMEOUT} || exit 1
	release_lock "${STASHNAME}.lock"
	# ... before hibernating
	pm-hibernate
}

auto_hibernate () {
	now=`cat "${RTC}/since_epoch"`
	wakealarm=`cat "${RTC}/wakealarm"`
	alarm_time=`restorestate auto-hibernate-alarm`
	if [ -n "${alarm_time}" ]; then
		if [ ${now} -ge ${alarm_time} -a ${now} -lt $((alarm_time + 30)) ]; then
			echo "Woken up by RTC, auto-hibernating ..."
			schedule_hibernate &
		elif [ "${alarm_time}" = "${wakealarm}" ]; then
			# cancel alarm
			echo > "${RTC}/wakealarm"
		fi
	fi
}

case $1 in
	suspend) schedule_alarm ;;
	resume) auto_hibernate ;;
	help) help ;;
	*) exit $NA ;;
esac


/etc/pm-utils-auto-hibernate.conf:

# RTC="/sys/class/rtc/rtc0"
TIME_TO_HIBERNATE=30
AUTO_HIBERNATE_ENABLED=y