From a533096685196b29fcc3a8707f266034d24ee489 Mon Sep 17 00:00:00 2001
From: isabel <isabel@isabelroses.com>
Date: Mon, 20 Apr 2026 00:44:52 +0100
Subject: [PATCH] nixos/enviroment: remove zram; add zswap

oomfie said zswap is better for most cases
---
 modules/nixos/environment/default.nix |  2 +-
 modules/nixos/environment/zram.nix    | 23 -----------------------
 modules/nixos/environment/zswap.nix   | 14 ++++++++++++++
 3 files changed, 15 insertions(+), 24 deletions(-)
 delete mode 100644 modules/nixos/environment/zram.nix
 create mode 100644 modules/nixos/environment/zswap.nix

diff --git a/modules/nixos/environment/default.nix b/modules/nixos/environment/default.nix
index efb5bb20..9f31bb7b 100644
--- a/modules/nixos/environment/default.nix
+++ b/modules/nixos/environment/default.nix
@@ -8,7 +8,7 @@
     ./paths.nix # paths
     ./wayland.nix # wayland settings
     ./xdg.nix # move everything to nice placee
-    ./zram.nix # zram optimisation and enabling
+    ./zswap.nix # zswap optimisation and enabling
     # keep-sorted end
   ];
 }
diff --git a/modules/nixos/environment/zram.nix b/modules/nixos/environment/zram.nix
deleted file mode 100644
index 39acf575..00000000
--- a/modules/nixos/environment/zram.nix
+++ /dev/null
@@ -1,23 +0,0 @@
-{ lib, config, ... }:
-let
-  inherit (lib) mkIf;
-in
-{
-  # compress half of the ram to use as swap basically, get more memory per memory
-  zramSwap = {
-    enable = true;
-    algorithm = "zstd";
-
-    # defaults to 50
-    memoryPercent = 90;
-  };
-
-  boot.kernel.sysctl = mkIf config.zramSwap.enable {
-    # zram is relatively cheap, prefer swap
-    "vm.swappiness" = 180;
-    "vm.watermark_boost_factor" = 0;
-    "vm.watermark_scale_factor" = 125;
-    # zram is in memory, no need to readahead
-    "vm.page-cluster" = 0;
-  };
-}
diff --git a/modules/nixos/environment/zswap.nix b/modules/nixos/environment/zswap.nix
new file mode 100644
index 00000000..e20cec6b
--- /dev/null
+++ b/modules/nixos/environment/zswap.nix
@@ -0,0 +1,14 @@
+{ lib, config, ... }:
+let
+  inherit (lib) mkIf;
+in
+{
+  # compress half of the ram to use as swap basically, get more memory per memory
+  # <https://chrisdown.name/2026/03/24/zswap-vs-zram-when-to-use-what.html>
+  boot.zswap = {
+    enable = config.swapDevices != [ ];
+
+    # defaults are good when its not a server
+    maxPoolPercent = mkIf config.garden.profiles.server.enable 15;
+  };
+}
-- 
2.51.2