From d6db303160000efbd402e2910accedef648872e6 Mon Sep 17 00:00:00 2001
From: K900 <me@0upti.me>
Date: Tue, 16 May 2023 19:18:58 +0300
Subject: [PATCH] linux: enable RCU_LAZY where supported

Supposed to save some power at idle.
---
 pkgs/os-specific/linux/kernel/common-config.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkgs/os-specific/linux/kernel/common-config.nix b/pkgs/os-specific/linux/kernel/common-config.nix
index 3520f1bd5cfc..4d88df33376e 100644
--- a/pkgs/os-specific/linux/kernel/common-config.nix
+++ b/pkgs/os-specific/linux/kernel/common-config.nix
@@ -77,6 +77,10 @@ let
       ACPI_APEI                        = (option yes);
       # APEI Generic Hardware Error Source
       ACPI_APEI_GHES                   = (option yes);
+
+      # Enable lazy RCUs for power savings:
+      # https://lore.kernel.org/rcu/20221019225138.GA2499943@paulmck-ThinkPad-P17-Gen-1/
+      RCU_LAZY                         = whenAtLeast "6.2" yes;
     } // optionalAttrs (stdenv.hostPlatform.isx86) {
       INTEL_IDLE                       = yes;
       INTEL_RAPL                       = whenAtLeast "5.3" module;