Merge pull request #301064 from SuperSandro2000/redis-thp

nixos/redis: enable vmOverCommit by defaul; don't disable transparent hugepages

nixos/doc/manual/release-notes/rl-2405.section.md

@@ -293,6 +293,8 @@ The pre-existing [services.ankisyncd](#opt-services.ankisyncd.enable) has been m
 
 - `network-interfaces.target` system target was removed as it has been deprecated for a long time. Use `network.target` instead.
 
+- `services.redis.vmOverCommit` now defaults to `true` and no longer enforces Transparent Hugepages (THP) to be disabled. Redis only works with THP configured to `madvise` which is the kernel's default.
+
 - `azure-cli` now has extension support. For example, to install the `aks-preview` extension, use
 
   ```nix

nixos/modules/services/databases/redis.nix

@@ -57,9 +57,9 @@ in {
       package = mkPackageOption pkgs "redis" { };
 
       vmOverCommit = mkEnableOption ''
-        setting of vm.overcommit_memory to 1
+        set `vm.overcommit_memory` sysctl to 1
         (Suggested for Background Saving: <https://redis.io/docs/get-started/faq/>)
-      '';
+      '' // { default = true; };
 
       servers = mkOption {
         type = with types; attrsOf (submodule ({ config, name, ... }: {
@@ -312,10 +312,9 @@ in {
       '';
     }) enabledServers);
 
-    boot.kernel.sysctl = mkMerge [
-      { "vm.nr_hugepages" = "0"; }
-      ( mkIf cfg.vmOverCommit { "vm.overcommit_memory" = "1"; } )
-    ];
+    boot.kernel.sysctl = mkIf cfg.vmOverCommit {
+      "vm.overcommit_memory" = "1";
+    };
 
     networking.firewall.allowedTCPPorts = concatMap (conf:
       optional conf.openFirewall conf.port