feat(memory): declare 'memory' module

modules/common/embedded.nix

@@ -5,10 +5,8 @@
     system.autoUpgrade.enable = false;
     nix.settings.max-jobs = 0;
 
-    zramSwap = {
-      enable = true;
-      memoryPercent = 100;
-    };
+    memory.zram.enable = true;
+    zramSwap.memoryPercent = 100;
 
     services.journald.settings.Journal.SystemMaxUse = "100M";
   };

modules/memory/default.nix

@@ -0,0 +1,19 @@
+{ lib, ... }:
+
+{
+  imports = [
+    ./oom.nix
+    ./zram.nix
+  ];
+
+  options.memory = {
+    oom.enable = lib.mkOption {
+      default = false;
+      type = lib.types.bool;
+    };
+    zram.enable = lib.mkOption {
+      default = false;
+      type = lib.types.bool;
+    };
+  };
+}

modules/memory/oom.nix

@@ -0,0 +1,7 @@
+{ config, lib, ... }:
+
+{
+  config = lib.mkIf config.memory.oom.enable {
+    systemd.oomd.enableUserSlices = lib.mkDefault true;
+  };
+}

modules/memory/zram.nix

@@ -0,0 +1,11 @@
+{ config, lib, ... }:
+
+{
+  config = lib.mkIf config.memory.zram.enable {
+    zramSwap.enable = true;
+    boot.kernel.sysctl = {
+      "vm.swappiness" = lib.mkDefault 180;
+      "vm.page-cluster" = lib.mkDefault 0;
+    };
+  };
+}