1 files changed, 38 insertions, 0 deletions
diff --git a/nixos/modules/hardware/ksm.nix b/nixos/modules/hardware/ksm.nix
new file mode 100644
index 00000000000..829c3532c45
--- /dev/null
+++ b/nixos/modules/hardware/ksm.nix
@@ -0,0 +1,38 @@
+{ config, lib, ... }:
+
+with lib;
+
+let
+  cfg = config.hardware.ksm;
+
+in {
+  imports = [
+    (mkRenamedOptionModule [ "hardware" "enableKSM" ] [ "hardware" "ksm" "enable" ])
+  ];
+
+  options.hardware.ksm = {
+    enable = mkEnableOption "Kernel Same-Page Merging";
+    sleep = mkOption {
+      type = types.nullOr types.int;
+      default = null;
+      description = ''
+        How many milliseconds ksmd should sleep between scans.
+        Setting it to <literal>null</literal> uses the kernel's default time.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.enable-ksm = {
+      description = "Enable Kernel Same-Page Merging";
+      wantedBy = [ "multi-user.target" ];
+      script =
+        ''
+          echo 1 > /sys/kernel/mm/ksm/run
+        '' + optionalString (cfg.sleep != null)
+        ''
+          echo ${toString cfg.sleep} > /sys/kernel/mm/ksm/sleep_millisecs
+        '';
+    };
+  };
+}