zram-service/zram.sh

### BEGIN INIT INFO
# Provides:          zram
# Required-Start:    $local_fs
# Required-Stop:     $local_fs
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Use compressed RAM as in-memory swap
# Description:       Use compressed RAM as in-memory swap
### END INIT INFO

# script settings
# service name
ZRAM_SERVICE=zram
# service config file
ZRAM_CONFIG=zram-config
STREAMS=$(grep -c ^processor /proc/cpuinfo)

# defaults
ALGORITHM=lz4
RAM_PERCENTAGE=50
PRIORITY=100

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

echo () { printf %s\\n "$*" ; }

_start_() {
    if grep -q zram /proc/swaps; then
        echo "${ZRAM_SERVICE} already running, exiting"
        return 1
    else 

        modprobe "$ALGORITHM"
        modprobe zram
        sleep 1

        MEMORY_KB=$(awk '/MemTotal/{print $2}' /proc/meminfo)
        MEMORY_TOTAL=$(( MEMORY_KB * 1024 ))
        ZRAM_DISK_SIZE=$(( MEMORY_TOTAL * RAM_PERCENTAGE / 100))

        zramctl -f

        zramctl /dev/zram0 -s $ZRAM_DISK_SIZE -t $STREAMS -a $ALGORITHM

        echo "waiting for zram device"
        until [ -b /dev/zram0 ]; do
            sleep 1
        done

        echo "zram device initiated"
        echo "activating device"
        mkswap -L SWAP_ZRAM_0 /dev/zram0 && echo "zram device labeled"
        sleep 1
        swapon -p $PRIORITY /dev/zram0 && echo "zram device activated"

        echo "${ZRAM_SERVICE} started"
    fi
}

_stop_() {
    if ! zramctl -f; then
        echo "${ZRAM_SERVICE} NOT running, exiting"
        return 1
    else
        for n in $( seq $( grep -c "/dev/zram" /proc/swaps ) )
        do
            INDEX=$((n - 1))
            echo "deactivating /dev/zram$INDEX"
            swapoff /dev/zram$INDEX && echo "/dev/zram$INDEX deactivated"
            sleep 1
            zramctl -r /dev/zram$INDEX
        done

        wait
        sleep 1
        modprobe -r zram
        modprobe -r $ALGORITHM
        echo "${ZRAM_SERVICE} stopped"
    fi
}

_stat_() {
    zramctl
}

_restart_() {
    echo "${ZRAM_SERVICE} restarting"
    echo "${ZRAM_SERVICE} stopping"
    _stop_
    sleep 2
    echo "${ZRAM_SERVICE} starting"
    _start_

}

case "$1" in
    "start" | "init" ) _start_ ;;
    "stop" | "end" ) _stop_ ;;
    "stat" | "status" ) _stat_ ;;
    "restart" | "force-restart" ) _restart_ ;;
esac

# End of file