From a9e351e6b9fb6406292094f84cb3a1c07124ccd4 Mon Sep 17 00:00:00 2001
From: Jacob Birkett <jacob@birkett.dev>
Date: Sat, 19 Apr 2025 23:37:56 -0700
Subject: [PATCH] services: thinkfan: run with realtime priority

---
 nixos/modules/services/hardware/thinkfan.nix | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/nixos/modules/services/hardware/thinkfan.nix b/nixos/modules/services/hardware/thinkfan.nix
index 33f1ae422b2dc..ca4d91ff56a1e 100644
--- a/nixos/modules/services/hardware/thinkfan.nix
+++ b/nixos/modules/services/hardware/thinkfan.nix
@@ -291,10 +291,17 @@ in
       );
       thinkfan.serviceConfig = {
         Restart = "on-failure";
-        RestartSec = "30s";
+        RestartSec = "2s"; # slow restart is a problem if not exit cleanly
 
         # Hardening
         PrivateNetwork = true;
+
+        # Run this process with near-realtime priority.
+        # <https://github.com/vmatare/thinkfan/pull/198>
+        CPUSchedulingPolicy = "fifo";
+        CPUSchedulingPriority = 20; # high, but not the highest
+        OOMScoreAdjust = -1000; # never kill this unit if out of memory
+        MemorySwapMax = 0; # never swap
       };
 
       # must be added manually, see issue #81138