zram

#!/bin/bash

NUM_CPUS=$(nproc)
[ "$NUM_CPUS" != 0 ] || NUM_CPUS=1
NUM_DEVS=$NUM_CPUS
FACTOR=10 # percentage
TOTALRAM=$(grep MemTotal /proc/meminfo | awk ' { print $2 } ')
DISK_SIZE=$(($TOTALRAM/$NUM_CPUS*$FACTOR/100*1024))

#Defaults for vm.overcommit_memory, vm.page-cluster, vm.spwapiness
OVERCOMMIT_MEMORY=0
PAGE_CLUSTER=3
SPWAPINESS=60


start() {
  [ ! -e /sys/module/zram ] && modprobe zram num_devices=$NUM_DEVS || modprobe -r zram && modprobe zram num_devices=$NUM_DEVS
  for i in /sys/block/zram*; do
    /usr/bin/echo $DISK_SIZE > ${i}/disksize;
  done

  for i in /dev/zram*; do
    /usr/sbin/mkswap ${i};
    /usr/sbin/swapon -d -p100 ${i};
  done
  
  echo 1 > /proc/sys/vm/overcommit_memory
  echo 0 > /proc/sys/vm/page-cluster
  echo 100 > /proc/sys/vm/swappiness
}

stop() {
  [ ! -e /sys/module/zram ] && exit 0

  echo $OVERCOMMIT_MEMORY > /proc/sys/vm/overcommit_memory
  echo $PAGE_CLUSTER > /proc/sys/vm/page-cluster
  echo $SPWAPINESS > /proc/sys/vm/swappiness

  for i in /dev/zram*; do
    /usr/sbin/swapoff ${i};
  done

  for i in /sys/block/zram*; do
    /usr/bin/echo 1 > ${i}/reset;
  done
  [ -e /sys/module/zram ] && modprobe -r zram
}

case $1 in
  (start|stop) "$1" ;;
esac