zram-config

#!/bin/bash
### BEGIN INIT INFO
# Provides: zram
# Required-Start: $local_fs
# Required-Stop:
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: enable swap with compressed ram block device backend
# Description: Adapted from script written by tradetaxfree and is found at http://crunchbanglinux.org/forums/topic/15344/zram-a-good-idea/
# also ported from Ubuntu's upstart version of zram-config
### END INIT INFO

# Author: David Sobon <d@sobon.org>

DESC="zram-config"
NAME="zram-config"

# percentage of real memory to use for zram.
# note: pre-compressed amount. real memory usage may end up 30-60%
ZRAM_FACTOR=50

# Read configuration variable file if it is present
[ -r /etc/default/$NAME ] && . /etc/default/$NAME

# Load the VERBOSE setting and other rcS variables
. /lib/init/vars.sh

# Define LSB log_* functions.
# Depend on lsb-base (>= 3.2-14) to ensure that this file is present
# and status_of_proc is working.
. /lib/lsb/init-functions

#
# start
#
do_start() {
	NRDEVICES=$(grep -c ^processor /proc/cpuinfo | sed 's/^0$/1/')

	if modinfo zram | grep -q ' zram_num_devices:' 2>/dev/null; then
		MODPROBE_ARGS="zram_num_devices=${NRDEVICES}"
	elif modinfo zram | grep -q ' num_devices:' 2>/dev/null; then
		MODPROBE_ARGS="num_devices=${NRDEVICES}"
	else
		exit 1
	fi
	modprobe zram $MODPROBE_ARGS

	if [ $? -gt 0 ]; then
		log_failure_msg "Your Kernel needs to be compiled with ZRAM support."
		exit 1
	fi

	# Calculate memory to use for zram.
	totalmem=`free | grep -e "^Mem:" | sed -e 's/^Mem: *//' -e 's/  *.*//'`
	mem=$(((totalmem / ${NRDEVICES} * ${ZRAM_FACTOR} / 100) * 1024))

	# initialize the devices
	for i in $(seq ${NRDEVICES}); do
		DEVNUMBER=$((i - 1))
		echo $mem > /sys/block/zram${DEVNUMBER}/disksize

		RETVAL=$?
		if [ $RETVAL -gt 0 ]; then
			log_failure_msg "/dev/zram# already in use!"
			return $RETVAL
		fi

		mkswap /dev/zram${DEVNUMBER} >/dev/null
		swapon -p 5 /dev/zram${DEVNUMBER} >/dev/null
	done

	return 0
}

#
# stop
#
do_stop() {
	if DEVICES=$(grep zram /proc/swaps | awk '{print $1}'); then
		for i in $DEVICES; do
			swapoff $i >/dev/null
		done
	fi

	rmmod -w zram  1>/dev/null 2>&1
	RETVAL=$?

	return $RETVAL
}

#
# do_status
#
function do_status () {
	I=$(/sbin/swapon -s | grep zram | wc -l)

	if [ $I -eq 0 ]; then
		echo "$NAME is NOT running."
		exit 3
	fi

	echo "$NAME is running."
	exit 0
}

#
#
#
case "$1" in
	start)
		log_daemon_msg "Starting $DESC"
		do_start
		case "$?" in
			0|1) log_end_msg 0 ;;
			2)   log_end_msg 1 ;;
		esac
		;;
	stop)
		log_daemon_msg "Stopping $DESC"
		do_stop
		case "$?" in
			0|1) log_end_msg 0 ;;
			2)   log_end_msg 1 ;;
		esac
		;;
	restart|force-reload)
		do_stop
		sleep 1
		do_start
		;;
	status)
		do_status
		;;
	*)
		echo "Usage: $0 {start|stop|restart}"
		RETVAL=1
esac

exit $RETVAL