linux-kernel - [PATCH v3 1/2] sched/core: Remove HK_TYPE

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Message-ID: <20240904183650.1053708-2-longman@redhat.com>
Date: Wed,  4 Sep 2024 14:36:49 -0400
From: Waiman Long <longman@...hat.com>
To: Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Frederic Weisbecker <frederic@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	Phil Auld <pauld@...hat.com>,
	Waiman Long <longman@...hat.com>
Subject: [PATCH v3 1/2] sched/core: Remove HK_TYPE_SCHED

The HK_TYPE_SCHED housekeeping type is defined but not set anywhere. So
any code that try to use HK_TYPE_SCHED are essentially dead code. So
remove HK_TYPE_SCHED and any code that use it.

Signed-off-by: Waiman Long <longman@...hat.com>
---
 include/linux/sched/isolation.h |  1 -
 kernel/sched/fair.c             | 14 --------------
 kernel/sched/isolation.c        |  1 -
 3 files changed, 16 deletions(-)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 2b461129d1fa..499d5e480882 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -10,7 +10,6 @@ enum hk_type {
 	HK_TYPE_TIMER,
 	HK_TYPE_RCU,
 	HK_TYPE_MISC,
-	HK_TYPE_SCHED,
 	HK_TYPE_TICK,
 	HK_TYPE_DOMAIN,
 	HK_TYPE_WQ,
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9057584ec06d..ac5ed846fb55 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11840,9 +11840,6 @@ static inline int on_null_domain(struct rq *rq)
  * - When one of the busy CPUs notices that there may be an idle rebalancing
  *   needed, they will kick the idle load balancer, which then does idle
  *   load balancing for all the idle CPUs.
- *
- * - HK_TYPE_MISC CPUs are used for this task, because HK_TYPE_SCHED is not set
- *   anywhere yet.
  */
 static inline int find_new_ilb(void)
 {
@@ -12087,10 +12084,6 @@ void nohz_balance_enter_idle(int cpu)
 	if (!cpu_active(cpu))
 		return;
 
-	/* Spare idle load balancing on CPUs that don't want to be disturbed: */
-	if (!housekeeping_cpu(cpu, HK_TYPE_SCHED))
-		return;
-
 	/*
 	 * Can be set safely without rq->lock held
 	 * If a clear happens, it will have evaluated last additions because
@@ -12310,13 +12303,6 @@ static void nohz_newidle_balance(struct rq *this_rq)
 {
 	int this_cpu = this_rq->cpu;
 
-	/*
-	 * This CPU doesn't want to be disturbed by scheduler
-	 * housekeeping
-	 */
-	if (!housekeeping_cpu(this_cpu, HK_TYPE_SCHED))
-		return;
-
 	/* Will wake up very soon. No time for doing anything else*/
 	if (this_rq->avg_idle < sysctl_sched_migration_cost)
 		return;
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 5891e715f00d..5345e11f3d44 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -12,7 +12,6 @@ enum hk_flags {
 	HK_FLAG_TIMER		= BIT(HK_TYPE_TIMER),
 	HK_FLAG_RCU		= BIT(HK_TYPE_RCU),
 	HK_FLAG_MISC		= BIT(HK_TYPE_MISC),
-	HK_FLAG_SCHED		= BIT(HK_TYPE_SCHED),
 	HK_FLAG_TICK		= BIT(HK_TYPE_TICK),
 	HK_FLAG_DOMAIN		= BIT(HK_TYPE_DOMAIN),
 	HK_FLAG_WQ		= BIT(HK_TYPE_WQ),
-- 
2.43.5