refactor: make power management compatible with zramSwap

Dynamically enable zramSwap if no swapDevices exist.
wimpysworld · Aug 12, 2024 · 983721d · 983721d
1 parent 655eac3
commit 983721d
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Showing 4 changed files with 36 additions and 16 deletions.
diff --git a/nixos/_mixins/features/power-management/default.nix b/nixos/_mixins/features/power-management/default.nix
@@ -2,17 +2,34 @@
 let
   isIntelCPU = config.hardware.cpu.intel.updateMicrocode;
   isLaptop = hostname != "vader" && hostname != "phasma" && hostname != "revan";
-  GNOMEIsenabled = config.services.xserver.desktopManager.gnome.enable == true;
   isThinkpad = hostname == "tanis" || hostname == "sidious"|| hostname == "shaa";
+  usePowerProfiles = config.services.xserver.desktopManager.gnome.enable || config.services.xserver.desktopManager.pantheon.enable;
 in
 lib.mkIf isInstall {
+  # Power Management strategy:
+  # - If a desktop environment is enabled the supports the power-profiles-daemon, then use the power profiles daemon.
+  #   - Otherwise, use auto-cpufreq.
+  # - If zramSwap is enabled, then disable power management features that conflict with zram.
+  # - Always disable TLP and Powertop because they conflict with auto-cpufreq or agressively suspend USB devices
+  # - Disable USB autosuspend on desktop workstations
+  # - Enable thermald on Intel CPUs
+  # - Thinkpads have a battery threshold charging either via the GNOME extension or auto-cpufreq
+
+  # Disable USB autosuspend on desktop always on power workstations
+  boot.kernelParams = lib.optionals (!isLaptop) [
+    "usbcore.autosuspend=-1"
+  ];
+
   # Install Battery Threshold GNOME extensions for Thinkpads
-  environment.systemPackages = with pkgs; lib.optionals (isThinkpad && GNOMEIsenabled) [
+  environment.systemPackages = with pkgs; lib.optionals (isThinkpad && config.services.xserver.desktopManager.gnome.enable) [
     gnomeExtensions.thinkpad-battery-threshold
   ];
+
+  powerManagement.powertop.enable = lib.mkDefault false;
+
   programs = {
     auto-cpufreq = {
-      enable = (!GNOMEIsenabled && isLaptop);
+      enable = (!usePowerProfiles && isLaptop);
       settings = {
         battery = {
           governor = "powersave";
@@ -32,12 +49,18 @@ lib.mkIf isInstall {
       };
     };
   };
+
   services = {
-    # Only enable power-profiles-daemon if GNOME is enabled
-    power-profiles-daemon.enable = (GNOMEIsenabled && isLaptop);
+    # Only enable power-profiles-daemon if the desktop environment supports it
+    power-profiles-daemon.enable = usePowerProfiles;
     # Only enable thermald on Intel CPUs
     thermald.enable = isIntelCPU;
     # Disable TLP because it conflicts with auto-cpufreq
     tlp.enable = lib.mkForce false;
   };
+
+  # Disable hiberate, hybrid-sleep and suspend-then-hibernate when zram swap is enabled.
+  systemd.targets.hibernate.enable = !config.zramSwap.enable;
+  systemd.targets.hybrid-sleep.enable = !config.zramSwap.enable;
+  systemd.targets.suspend-then-hibernate.enable = !config.zramSwap.enable;
 }
diff --git a/nixos/_mixins/features/zram/default.nix b/nixos/_mixins/features/zram/default.nix
@@ -1,14 +1,18 @@
-{ pkgs, ... }:
+{ config, lib, pkgs, ... }:
+let
+  # Only enable zram swap if no swap devices are configured
+  usezramSwap = builtins.length config.swapDevices == 0;
+in
 {
   # Keep zram swap (lz4) latency in check
-  boot.kernel.sysctl = {
+  boot.kernel.sysctl = lib.mkIf usezramSwap {
     "vm.page-cluster" = 1;
   };
 
   # Enable Multi-Gen LRU:
   # - https://docs.kernel.org/next/admin-guide/mm/multigen_lru.html
   # - Inspired by: https://github.com/hakavlad/mg-lru-helper
-  systemd.services."mglru" = {
+  systemd.services."mglru" = lib.mkIf usezramSwap {
     enable = true;
     wantedBy = [ "basic.target" ];
     script = ''
@@ -23,15 +27,12 @@
     };
   };
 
-  # Disable hiberate and hybrid-sleep when using zram.
-  systemd.targets.hibernate.enable = false;
-  systemd.targets.hybrid-sleep.enable = false;
   # Enable zram
   # - https://github.com/ecdye/zram-config/blob/main/README.md#performance
   # - https://www.reddit.com/r/Fedora/comments/mzun99/new_zram_tuning_benchmarks/
   # - https://linuxreviews.org/Zram
   zramSwap = {
     algorithm = "lz4";
-    enable = true;
+    enable = usezramSwap;
   };
 }
diff --git a/nixos/phasma/default.nix b/nixos/phasma/default.nix
@@ -40,8 +40,6 @@
     ];
     kernelPackages = lib.mkForce pkgs.linuxPackages_xanmod_latest;
     kernelParams = [
-      # Disable USB autosuspend on workstations
-      "usbcore.autosuspend=-1"
       "video=DP-1:3440x1440@60"
       "video=DP-2:1920x1080@60"
       "video=HDMI-A-1:1920x1080@60"

diff --git a/nixos/vader/default.nix b/nixos/vader/default.nix
@@ -41,8 +41,6 @@
     ];
     kernelPackages = lib.mkForce pkgs.linuxPackages_xanmod_latest;
     kernelParams = [
-      # Disable USB autosuspend on workstations
-      "usbcore.autosuspend=-1"
       "video=DP-1:2560x2880@60"
       "video=DP-2:2560x2880@60"
       "video=DP-3:1920x1080@60"