zRam

ZRam is a kernel module that provides a compressed block device in RAM. This block device can be mounted as a swap device. When the system RAM starts to fill the kernel dynamicly compresses some of the information and moves it into the block device. This is much faster than a traditional swap as it all happens in ram. There is a small cpu hit. For systems with limited ram and storage or slow storage such as an old PC, Laptop or raspberry pi. With lz4 compression there is about a 2.5 compression ratio. However some space needs to be left in RAM for decompression of memory.

zRam documentation on kernel.org

zRam for impoving performance at wiki.archlinux.org

Create zRam on arch linux techrapiduk.blogspot.com

Try out zRam

This assumes there is no current swap setup.

Load the zram kernel module.

sudo modprobe zram

Set compression algorithm to lz4.

sudo bash -c "echo 'lz4' > /sys/block/zram0/comp_algorithm"

Set the size of the zram device.

The size should not exceed 2.5 the size of the actual RAM. To find the systems RAM size in kb try this command.
grep MemTotal /proc/meminfo

For double that size in MegaBytes instead of KiloBites try this.
echo $(($( grep MemTotal /proc/meminfo | grep -o '[0-9]*' ) / 500))M

If that gave you a number that looks good. Use this command to set it.
sudo bash -c "echo $(($( grep MemTotal /proc/meminfo | grep -o '[0-9]*' ) / 500))M > /sys/block/zram0/disksize"

If the above commands didn't work for you. You can choose a number manually in M or G Megabytes or Gigabytes. With a command like this.
sudo bash -c "echo '2G' > /sys/block/zram0/disksize"

Create a swap device.

sudo mkswap --label zram0 /dev/zram0

Set the priority of the swap device.

sudo swapon --priority 100 /dev/zram0

Check if swap is working.

If htop is installed it will show the active RAM/Swap size.
htop

Disable zRam.

This isn't needed if zram is working. zRam will not be recreated on next boot. See systemd section.

Disabling zram swap.

sudo swapoff /dev/zram0

Unloading zRam kernel module.

sudo rmmod zram

Auto create zRam with systemd service.

A simple zram.service file using the above commands can be used to make a systemd service.

Download zram.service

wget https://raw.githubusercontent.com/JeremiahCheatham/zRam/main/zram.service
or
curl -LO https://raw.githubusercontent.com/JeremiahCheatham/zRam/main/zram.service

Copy zram.service file into place.

sudo cp zram.service /etc/systemd/system

Enable zram.service.

sudo systemctl enable zram

Start zram.service.

sudo systemctl start zram

Disbale or remove zram.service.

Stop zram.service.

sudo systemctl stop zram

Disable zram.service.

sudo systemctl disable zram

Remove zram.service file. First stop and disable zram.service.

sudo rm /etc/systemd/system/zram.service