nixos/profiles/systems/zramSwap.nix

   1 { pkgs, lib, config, ... }:
   2 {
   3 zramSwap = {
   4   enable = true;
   5   algorithm = lib.mkDefault "zstd";
   6   memoryPercent = lib.mkDefault 50;
   7   swapDevices = lib.mkDefault 1;
   8 };
   9
  10 boot.kernel.sysctl = {
  11   # Increase cache pressure, which increases the tendency of the kernel to
  12   # reclaim memory used for caching of directory and inode objects. You will use
  13   # less memory over a longer period of time. The performance hit is negated by
  14   # the downside of swapping sooner.
  15   "vm.vfs_cache_pressure" = lib.mkDefault 500;
  16
  17   # Increasing how aggressively the kernel will swap memory pages since we are
  18   # using ZRAM first.
  19   "vm.swappiness" = lib.mkDefault 100;
  20
  21   # Background processes will start writing right away when it hits the 1% limit
  22   "vm.dirty_background_ratio" = lib.mkDefault 1;
  23
  24   # The system won’t force synchronous I/O until it gets to 50% dirty_ratio.
  25   "vm.dirty_ratio" = lib.mkDefault 50;
  26 };
  27 }