linux-kernel - [PATCH 2/5] sched/debug: Make 'const_debug' tunables unconditional __read

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Message-ID: <20250317104257.3496611-3-mingo@kernel.org>
Date: Mon, 17 Mar 2025 11:42:53 +0100
From: Ingo Molnar <mingo@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Dietmar Eggemann <dietmar.eggemann@....com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Shrikanth Hegde <sshegde@...ux.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Mel Gorman <mgorman@...e.de>,
	Vincent Guittot <vincent.guittot@...aro.org>
Subject: [PATCH 2/5] sched/debug: Make 'const_debug' tunables unconditional __read_mostly

With CONFIG_SCHED_DEBUG becoming unconditional, remove the
extra 'const_debug' indirection towards __read_mostly.

Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/core.c  |  4 ++--
 kernel/sched/fair.c  |  2 +-
 kernel/sched/sched.h | 15 +++++----------
 3 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2da197b2968b..d6833a85e561 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -128,7 +128,7 @@ DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
  */
 #define SCHED_FEAT(name, enabled)	\
 	(1UL << __SCHED_FEAT_##name) * enabled |
-const_debug unsigned int sysctl_sched_features =
+__read_mostly unsigned int sysctl_sched_features =
 #include "features.h"
 	0;
 #undef SCHED_FEAT
@@ -148,7 +148,7 @@ __read_mostly int sysctl_resched_latency_warn_once = 1;
  * Number of tasks to iterate in a single balance run.
  * Limited because this is done with IRQs disabled.
  */
-const_debug unsigned int sysctl_sched_nr_migrate = SCHED_NR_MIGRATE_BREAK;
+__read_mostly unsigned int sysctl_sched_nr_migrate = SCHED_NR_MIGRATE_BREAK;
 
 __read_mostly int scheduler_running;
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 89609ebd4904..35ee8d9d78d5 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -79,7 +79,7 @@ unsigned int sysctl_sched_tunable_scaling = SCHED_TUNABLESCALING_LOG;
 unsigned int sysctl_sched_base_slice			= 700000ULL;
 static unsigned int normalized_sysctl_sched_base_slice	= 700000ULL;
 
-const_debug unsigned int sysctl_sched_migration_cost	= 500000UL;
+__read_mostly unsigned int sysctl_sched_migration_cost	= 500000UL;
 
 static int __init setup_sched_thermal_decay_shift(char *str)
 {
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 189f7b033dab..187a22800577 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2194,13 +2194,8 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
 }
 
 /*
- * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
+ * Tunables:
  */
-#ifdef CONFIG_SCHED_DEBUG
-# define const_debug __read_mostly
-#else
-# define const_debug const
-#endif
 
 #define SCHED_FEAT(name, enabled)	\
 	__SCHED_FEAT_##name ,
@@ -2218,7 +2213,7 @@ enum {
  * To support run-time toggling of sched features, all the translation units
  * (but core.c) reference the sysctl_sched_features defined in core.c.
  */
-extern const_debug unsigned int sysctl_sched_features;
+extern __read_mostly unsigned int sysctl_sched_features;
 
 #ifdef CONFIG_JUMP_LABEL
 
@@ -2249,7 +2244,7 @@ extern struct static_key sched_feat_keys[__SCHED_FEAT_NR];
  */
 #define SCHED_FEAT(name, enabled)	\
 	(1UL << __SCHED_FEAT_##name) * enabled |
-static const_debug __maybe_unused unsigned int sysctl_sched_features =
+static __read_mostly __maybe_unused unsigned int sysctl_sched_features =
 #include "features.h"
 	0;
 #undef SCHED_FEAT
@@ -2837,8 +2832,8 @@ extern void wakeup_preempt(struct rq *rq, struct task_struct *p, int flags);
 # define SCHED_NR_MIGRATE_BREAK 32
 #endif
 
-extern const_debug unsigned int sysctl_sched_nr_migrate;
-extern const_debug unsigned int sysctl_sched_migration_cost;
+extern __read_mostly unsigned int sysctl_sched_nr_migrate;
+extern __read_mostly unsigned int sysctl_sched_migration_cost;
 
 extern unsigned int sysctl_sched_base_slice;
 
-- 
2.45.2