# Documentation: https://www.kernel.org/doc/html/latest/admin-guide/mm/zswap.html
# Explanation: https://chrisdown.name/2026/03/24/zswap-vs-zram-when-to-use-what.html
{
  config,
  lib,
  ...
}:
let
  cfg = config.zswap;
in
{
  options.zswap = {
    enable = lib.mkEnableOption "zswap compressed swap cache" // {
      default = true;
    };

    maxPoolPercent = lib.mkOption {
      type = lib.types.int;
      default = 50;
      description = "Maximum percentage of RAM to use for the zswap pool.";
    };
  };

  config = lib.mkIf cfg.enable {
    boot = {
      kernelParams = [
        "zswap.enabled=1"
        "zswap.compressor=zstd"
        "zswap.max_pool_percent=${toString cfg.maxPoolPercent}"
        "zswap.shrinker_enabled=1"
        "zswap.zpool=zsmalloc"
      ];
      initrd.kernelModules = [
        "zsmalloc"
        "zstd"
      ];
    };

  };
}