Setup zram as swap quick and dirty

zram2swap.sh

#!/usr/bin/env bash
zramctl=$(command -v zramctl)
if [[ -z "$zramctl" ]];then
  echo "Command zramctl not found" 1>&2
  exit 2
fi

if swapon -s |grep '^/dev/zram' > /dev/null ; then
  echo "zram already setup as swap"
  exit 0
fi

set -eux -o pipefail
modprobe zram
nproc=$(nproc)
size=$(grep '^MemTotal:' /proc/meminfo |awk '{print $2/1024/8}')
# default use lz4; with max available thread and 1/8 total ram
# so, zram device can use 1/8 of our ram with incompressible data
# + a small overhead
zdevice=$($zramctl --find --size ${size%.*}M -a lz4 -t $nproc)
if [[ ! -b "${zdevice}" ]];then
  sleep 2 ## add a pause if device is not available
fi
mkswap --label zram4swap ${zdevice}
swapon --priority 100 ${zdevice}
# restore default swapiness value
sysctl -w vm.swappiness=60