Systemd zRAM service

Use a part of your RAM as compressed swap.

zram is a Linux kernel feature that provides a form of virtual memory compression. zram module increases performance by avoiding paging to disk and using a compressed block device in RAM instead, inside which paging takes place until it is necessary to use the swap space on a hard disk drive. Since using zram is an alternative way to provide swapping on RAM, zram allows Linux to make a better use of RAM when swapping/paging is required, especially on older computers with less RAM installed. It also eliminates wear on a microSD used in a Raspberry Pi by moving swap space off of the flash memory and into RAM.

See also: https://www.kernel.org/doc/Documentation/blockdev/zram.txt

***REN *** Contrary to the above documents - the zram device is NOT automatically provided in all kernels. This version of systemd-zram addresses this issue:

*** REN *** With the Ubuntu 21.10 release, Ubuntu removed the zram module and it must be installed with linux-modules-extra-raspi. There was also a recent article in "Make Use of" pointed out that there is also a way to enable the swapping feature on a Raspberry PI by adding the line "zswap.enable=1" to the end of /boot/firmware/cmdline.txt This program provides a systemd service to automatically load and configure such module at system boot.

ecdye/zram-config#71

https://www.makeuseof.com/boost-ubuntu-performance-on-raspberry-pi-4/

You can choose compression algorithm by editing systemd service. To see available algorithms do cat /sys/block/zram0/comp_algorithm.

You can choose to have systems with less then 1GB of RAM to have up to 2 * the ram space used for zram swap. Edit the systemd service to say yes|no

Installation

You can choose between different installation methods. Note that uninstallation doesn't remove active zram disk(s).

Classic method

• Build and install:

    $ make
    # sudo make install
  

• Uninstall:

    # sudo make uninstall
  

Debian package

• Build and install:

    $ make debian_pkg
    # sudo dpkg -i systemd-zram_*.deb
  

• Uninstall:

    # apt purge systemd-zram
  

Arch Linux package

• Build and install:

    $ make arch_pkg
    # sudo pacman -U systemd-zram-*.pkg.tar.xz
  

Alternatively you can install it from AUR:

    $ trizen -S systemd-zram

• Uninstall:

    # sudo pacman -Rsc systemd-zram
  

Usage

To start the service execute as root:

    # sudo systemctl start systemd-zram

To stop it:

    # sudo systemctl stop systemd-zram

If you want to enable zram at boot, just run as root:

    # sudo systemctl enable systemd-zram

And for disable it at boot:

    # sudo systemctl disable systemd-zram