#!/bin/bash
### BEGIN INIT INFO
# Provides: zram
# Required-Start:
# Required-Stop:
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Increased Performance In Linux With zRam (Virtual Swap Compressed in RAM)
# Description: Adapted from systemd scripts at https://github.com/mystilleef/FedoraZram
# Included as part of antix-goodies package by anticapitalista <antiX@operamail.com>
# This script was written by tradetaxfree and is found at http://crunchbanglinux.org/forums/topic/15344/zram-a-good-idea/
# Copy this script (as root) from /usr/local/bin to /etc/init.d and then #update-rc.d zram defaults
# After booting verify the module is loaded with: lsmod | grep zram
### END INIT INFO

start() {
    # get the number of CPUs
    num_cpus=$(grep -c processor /proc/cpuinfo)
    # if something goes wrong, assume we have 1
    [ "$num_cpus" != 0 ] || num_cpus=1

    # set decremented number of CPUs
    last_cpu=$((num_cpus - 1))

    #default Factor % = 90 change this value here or create /etc/default/zram
    FACTOR=90
    #& put the above single line in /etc/default/zram with the value you want
    [ -f /etc/default/zram ] && source /etc/default/zram || true
    factor=$FACTOR # percentage

    # get the amount of memory in the machine
    memtotal=$(grep MemTotal /proc/meminfo | awk ' { print $2 } ')
    mem_by_cpu=$(($memtotal/$num_cpus*$factor/100*1024))

    # load dependency modules
    # kernels 3.4 onwards

    modprobe zram num_devices=$num_cpus

    if [ $? -gt 0 ]; then
      # kernels 3.1 - 3.3
      #modprobe zram zram_num_devices=$num_cpus
    #else
      echo -e "Your Kernel needs to be compiled with ZRAM support:" \
      "\n\nDevice Drivers --> Staging Drivers --> Compressed RAM block device support (M)" \
      "\nDevice Drivers --> Staging Drivers --> Dynamic compression of swap pages and clean pagecache pages (*)" \
      "\n\nThe Liquorix Kernel (http://liquorix.net) has ZRAM support built in."
      exit 1
    fi
    echo "zram devices probed successfully"

    # initialize the devices
    for i in $(seq 0 $last_cpu); do
    echo $mem_by_cpu > /sys/block/zram$i/disksize
    # Creating swap filesystems
    mkswap /dev/zram$i
    # Switch the swaps on
    swapon -p 100 /dev/zram$i
    done
}

stop() {
    # get the number of CPUs
    num_cpus=$(grep -c processor /proc/cpuinfo)

    # set decremented number of CPUs
    last_cpu=$((num_cpus - 1))

    # Switching off swap
    for i in $(seq 0 $last_cpu); do
    if [ "$(grep /dev/zram$i /proc/swaps)" != "" ]; then
    swapoff /dev/zram$i
    sleep 1
    fi
    done

    sleep 1
    rmmod zram
}

case "$1" in
    start)
        start
        ;;
    stop)
        stop
        ;;
    restart)
        stop
        sleep 3
        start
        ;;
    *)
        echo "Usage: $0 {start|stop|restart}"
        RETVAL=1
esac
exit $RETVAL