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Script for creating hybrid swap space from zram swaps, swap files and swap partitions.

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systemd-swap

Script for manage swap on:

  • zswap - Enable/Configure
  • zram - Autoconfigurating for swap
  • files - (sparse files for saving space, support btrfs)
  • block devices - auto find and do swapon

ℹ️ It is configurable in /etc/systemd/swap.conf.

Additional terms:

  • SwapFC (File Chunked) - provide a dynamic swap file allocation/deallocation

Files placed

/etc/systemd/swap.conf
/usr/lib/systemd/system/systemd-swap.service
/usr/bin/systemd-swap

Please not forget to enable by

sudo systemctl enable systemd-swap

Install

  • Arch: in the community.

  • Debian: use package.sh in git repo

    git clone https://github.com/Nefelim4ag/systemd-swap.git
    ./systemd-swap/package.sh debian
    sudo dpkg -i ././systemd-swap/systemd-swap_*_all.deb
  • Fedora: use package.sh

    git clone https://github.com/Nefelim4ag/systemd-swap.git
    ./systemd-swap/package.sh fedora f28
    sudo dnf install ./systemd-swap/systemd-swap-*noarch.rpm
  • Manual

    git clone https://github.com/Nefelim4ag/systemd-swap.git
    sudo make install

About configuration

Q: WTF?! Why you merge swapFC and swapFU?
A: That simplify testing of swapFC code and make code more generic

Q: How can i migrate config swapFU from 3.X to 4.X?
A: Most of switches are same, to get configuration like swapFU from swapFC, set swapfc_max_count to 1 and swapfc_chunk_size to size of swapFU.

Q: Do we need to activate both zram and zswap?
A: Nope, it's useless, as zram is a compressed RAM DISK, but zswap is a compressed "writeback" CACHE on swap file/disk.

Q: Do i need use swapfc_force_use_loop on swapFC?
A: Nope, as you wish really, native swapfile must work faster and it's more safe in OOM condition in comparison to loop backed scenario.

Q: When would we want a certain configuration?
A: In most cases (Notebook, Desktop, Server) it's enough to enable zswap + swapfc (On server tuning of swapfc can be needed). In case where SSD used, and you care about flash wear, use only ZRam.

Q: Where is the swap file located?
A: Read carefully swap.conf

Q: Can we use this to enable hibernation?
A: Nope as hibernation wants a persistent fs blocks and wants access to swap data directly from disk, this will not work on: zram, swapfu, swapfc (without some magic of course).

Note

  • ℹ️ Zram dependence: util-linux >= 2.26

  • ℹ️ If you use zram not for only swap, use kernel 4.2+ or please add rule for modprobe like:

    options zram max_devices=32

Switch On Systemd Swap

  • For check your configuration:

    cat /proc/sys/vm/swappiness
    cat /proc/sys/vm/vfs_cache_pressure
  • Recomended configuration for Desktop:

    echo vm.swappiness=5 | sudo tee -a /etc/sysctl.d/99-sysctl.conf
    echo vm.vfs_cache_pressure=50 | sudo tee -a /etc/sysctl.d/99-sysctl.conf
    sudo sysctl -p /etc/sysctl.d/99-sysctl.conf
  • If you have install Systemd Swap check configuration:

    nano /etc/systemd/swap.conf
    zram_enabled=0
    zswap_enabled=1
    swapfc_enabled=1
  • Stop your swap:

    sudo swapoff -a
  • Need to remove swap from fstab:

    nano /etc/fstab
  • Remove your swap

    # For Ubuntu
    sudo rm -f /swapfile
    
    # For Centos 7
    lvremove -Ay /dev/centos/swap
    lvextend -l +100%FREE centos/root
  • Remove swap from Grub:

    # For Ubuntu remove resume* in grub
    nano /etc/default/grub
    
    # For Centos 7 remove rd.lvm.lv=centos/swap*
    nano /etc/default/grub
    
    # For Manjaro remove resume* in grub & mkinitcpio
    nano /etc/default/grub
    nano /etc/mkinitcpio.conf
    # For Ubuntu
    update-grub
    
    # For Centos 7
    update-grub
    
    # For Manjaro
    update-grub
    mkinitcpio -P

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Script for creating hybrid swap space from zram swaps, swap files and swap partitions.

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