linux-kernel - [PATCH v3] sched/fair: Remove cfs_rq::nr_spread_over and cfs_rq::exec

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Message-Id: <20240720031928.406540-1-zhouchuyi@bytedance.com>
Date: Sat, 20 Jul 2024 11:19:28 +0800
From: Chuyi Zhou <zhouchuyi@...edance.com>
To: mingo@...hat.com,
	peterz@...radead.org,
	juri.lelli@...hat.com,
	vincent.guittot@...aro.org,
	dietmar.eggemann@....com,
	rostedt@...dmis.org,
	bsegall@...gle.com
Cc: chengming.zhou@...ux.dev,
	linux-kernel@...r.kernel.org,
	Chuyi Zhou <zhouchuyi@...edance.com>,
	Vishal Chourasia <vishalc@...ux.ibm.com>,
	K Prateek Nayak <kprateek.nayak@....com>
Subject: [PATCH v3] sched/fair: Remove cfs_rq::nr_spread_over and cfs_rq::exec_clock

nr_spread_over tracks the number of instances where the difference
between a scheduling entity's virtual runtime and the minimum virtual
runtime in the runqueue exceeds three times the scheduler latency,
indicating significant disparity in task scheduling.
Commit 5e963f2bd465 ("sched/fair: Commit to EEVDF") removed its usage.

cfs_rq->exec_clock was used to account for time spent executing tasks.
Commit 5d69eca542ee ("sched: Unify runtime accounting across classes")
removed its usage.

cfs_rq::nr_spread_over and cfs_rq::exec_clock are not used anymore in
eevdf. Remove them from struct cfs_rq.

Signed-off-by: Chuyi Zhou <zhouchuyi@...edance.com>
Acked-by: Vishal Chourasia <vishalc@...ux.ibm.com>
Reviewed-by: Chengming Zhou <chengming.zhou@...ux.dev>
Reviewed-by: K Prateek Nayak <kprateek.nayak@....com>
---
Changes in v3:
Fix the commit description style suggested by Prateek.

Changes in v2:
Add more description of nr_spread_over and exec_clock
suggested by Vishal.
---
 kernel/sched/debug.c | 4 ----
 kernel/sched/sched.h | 6 ------
 2 files changed, 10 deletions(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index c1eb9a1afd13..90c4a9998377 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -641,8 +641,6 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
 	SEQ_printf(m, "\n");
 	SEQ_printf(m, "cfs_rq[%d]:\n", cpu);
 #endif
-	SEQ_printf(m, "  .%-30s: %Ld.%06ld\n", "exec_clock",
-			SPLIT_NS(cfs_rq->exec_clock));
 
 	raw_spin_rq_lock_irqsave(rq, flags);
 	root = __pick_root_entity(cfs_rq);
@@ -669,8 +667,6 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
 			SPLIT_NS(right_vruntime));
 	spread = right_vruntime - left_vruntime;
 	SEQ_printf(m, "  .%-30s: %Ld.%06ld\n", "spread", SPLIT_NS(spread));
-	SEQ_printf(m, "  .%-30s: %d\n", "nr_spread_over",
-			cfs_rq->nr_spread_over);
 	SEQ_printf(m, "  .%-30s: %d\n", "nr_running", cfs_rq->nr_running);
 	SEQ_printf(m, "  .%-30s: %d\n", "h_nr_running", cfs_rq->h_nr_running);
 	SEQ_printf(m, "  .%-30s: %d\n", "idle_nr_running",
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 4c36cc680361..8a071022bdec 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -599,7 +599,6 @@ struct cfs_rq {
 	s64			avg_vruntime;
 	u64			avg_load;
 
-	u64			exec_clock;
 	u64			min_vruntime;
 #ifdef CONFIG_SCHED_CORE
 	unsigned int		forceidle_seq;
@@ -619,10 +618,6 @@ struct cfs_rq {
 	struct sched_entity	*curr;
 	struct sched_entity	*next;
 
-#ifdef	CONFIG_SCHED_DEBUG
-	unsigned int		nr_spread_over;
-#endif
-
 #ifdef CONFIG_SMP
 	/*
 	 * CFS load tracking
@@ -1158,7 +1153,6 @@ struct rq {
 	/* latency stats */
 	struct sched_info	rq_sched_info;
 	unsigned long long	rq_cpu_time;
-	/* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */
 
 	/* sys_sched_yield() stats */
 	unsigned int		yld_count;
-- 
2.20.1