[djamba] added swap and zramSwap

hosts/djamba.nix

@@ -20,6 +20,19 @@
   # Use latest kernel.
   boot.kernelPackages = pkgs.linuxPackages_latest;
 
+  swapDevices = [{
+    device = "/var/lib/swapfile";
+    size = 32*1024; # 32 GiB
+    options = [ "discard" ];
+  }];
+  boot.kernel.sysctl = {
+    "vm.swappiness" = 20;
+  };
+  zramSwap = {
+    enable = true;
+    memoryMax = 6 * 1024 * 1024 * 1024;
+  };
+
   networking.hostName = "djamba"; # Define your hostname.
 
   # Enable networking