Automatically setup swap on zram ✨
- Significantly improves system responsiveness, especially when swap is under pressure.
- More secure, user data leaks into swap are on volatile media.
- Without swap-on-drive, there's better utilization of a limited resource: benefit of swap without the drive space consumption.
- Further reduces the time to out-of-memory kill, when workloads exceed limits.
See also https://fedoraproject.org/wiki/Changes/SwapOnZRAM#Benefit_to_Fedora
- Install the
zramdpackage form the AUR. - Enable and start the service:
sudo systemctl enable --now zramd
- Head to the releases section and download the
.debfile corresponding to your system architecture - Install using
sudo dpkg -i DEB_FILE
- Head to the releases section and download the
.tar.gzfile corresponding to your system architecture - Extract the downloaded file e.g.
tar xf TAR_FILE - Copy the
zramdbinary to/usr/local/bin. - There are various ways to setup autostart depending on your init system, for example you can add a line to
/etc/rc.locale.g./usr/local/bin/zramd start
-
zramd --help
Usage: zramd <command> [<args>] Options: --help, -h display this help and exit --version display version and exit Commands: start load zram module and setup swap devices stop stop swap devices and unload zram module -
zramd start --help
Usage: zramd start [--algorithm ALGORITHM] [--fraction FRACTION] [--max-size MAX_SIZE] [--num-devices NUM_DEVICES] [--priority PRIORITY] [--skip-vm] Options: --algorithm ALGORITHM, -a ALGORITHM zram compression algorithm [default: zstd, env: ALGORITHM] --fraction FRACTION, -f FRACTION maximum percentage of RAM allowed to use [default: 1.0, env: FRACTION] --max-size MAX_SIZE, -m MAX_SIZE maximum total MB of swap to allocate [default: 8192, env: MAX_SIZE] --num-devices NUM_DEVICES, -n NUM_DEVICES maximum number of zram devices to create [default: 1, env: NUM_DEVICES] --priority PRIORITY, -p PRIORITY swap priority [default: 100, env: PRIORITY] --skip-vm, -s skip initialization if running on a VM [default: false, env: SKIP_VM] --help, -h display this help and exit --version display version and exit
- Choose a valid git tag and run the
make dockercommand e.g.# This command will create builds (.tar.gz and .deb) for all supported architectures CURRENT_TAG=v0.8.5 make docker
- Install
go(at least version 1.16), the command may be different depending on the distribution:# ArchLinux sudo pacman -S go # Ubuntu sudo apt-get install golang
- You can run
maketo create a build with the same architecture as the current system:# If you cloned this repository you can just run make make # To create a Raspberry Pi build you need to specify the arch e.g. GOOS=linux GOARCH=arm GOARM=7 make # If you downloaded a .tar.gz or .zip (instead of cloning this repo) you need to specify additional info CURRENT_DATE=$(date --iso-8601=seconds) VERSION=Unknown make # So, to target the Raspberry Pi (without a repo) the command would look like CURRENT_DATE=$(date --iso-8601=seconds) VERSION=Unknown GOOS=linux GOARCH=arm GOARM=7 make
- A new executable called
zramd.binwill be created under thedist/directory, now you can uninstallgoif you like.
- The default configuration file is located at
/etc/default/zramd, just edit the variables as you like and restart thezramdservice i.e.sudo systemctl restart zramd
- Just change the arguments as you like, e.g.
zramd start --max-size 1024orzramd start --fraction 0.5 --priority 0
- modprobe: FATAL: Module zram not found in directory /lib/modules/...
It can happen if you try to start thezramdservice after a kernel upgrade, you just need to restart your computer. - error: swapon: /dev/zramX: swapon failed: Operation not permitted
First make sure that you are running as root (or at least that you have the required capabilities), also keep in mind that Linux only supports up to 32 swap devices (although it can start throwing the error from above when using a high value like 24).
- Avoid using other zram-related packages along this one,
zramdloads and unloads the zram kernel module assuming that the system is not using zram for other stuff (like mounting/tmpover zram). - Do not use zswap with zram, it would unnecessarily cause data to be compressed and decompressed back and forth.
- When dealing with virtual machines, zram should be used on the host OS so guest memory can be compressed transparently, see also comments on original zram implementation.
- If you boot the same system on a real computer as well as on a virtual machine, you can use the
--skip-vmparameter to avoid initialization when running inside a virtual machine.
- If you boot the same system on a real computer as well as on a virtual machine, you can use the
- For best results install
systemd-oomdorearlyoom(they may not be available on all distributions). - You can use
swapon -showorzramctlto see all swap devices currently in use, this is useful if you want to confirm that all of the zram devices were setup correctly. - To quickly fill the memory, you can use
tail /dev/zerobut keep in mind that your system may become unresponsive if you do not have an application likeearlyoomto killtailjust before it reaches the memory limit. - To test some zramd commands under the same conditions as the systemd unit you can use
systemd-rune.g.sudo systemd-run -t \ -p ProtectHostname=yes \ -p PrivateNetwork=yes \ -p IPAddressDeny=any \ -p NoNewPrivileges=yes \ -p RestrictNamespaces=yes \ -p RestrictRealtime=yes \ -p RestrictSUIDSGID=yes \ -p MemoryDenyWriteExecute=yes \ -p LockPersonality=yes \ -p 'CapabilityBoundingSet=CAP_SYS_ADMIN CAP_SYS_MODULE' \ -p 'SystemCallFilter=@module @swap @system-service' \ -p SystemCallArchitectures=native \ -p SystemCallErrorNumber=EPERM \ -p 'DeviceAllow=block-* rw' \ -p DevicePolicy=closed \ -p RestrictAddressFamilies=AF_UNIX \ -p RestrictAddressFamilies=~AF_UNIX \ /usr/bin/zramd --version
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