linux-kernel - [PATCH 4/4] sched_ext: Put event_stats_cpu in struct scx_sched

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Message-ID: <20250902234817.279206-5-tj@kernel.org>
Date: Tue,  2 Sep 2025 13:48:06 -1000
From: Tejun Heo <tj@...nel.org>
To: void@...ifault.com,
	arighi@...dia.com,
	multics69@...il.com
Cc: linux-kernel@...r.kernel.org,
	sched-ext@...a.com,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 4/4] sched_ext: Put event_stats_cpu in struct scx_sched_pcpu

scx_sched.event_stats_cpu is the percpu counters that are used to track
stats. Introduce struct scx_sched_pcpu and move the counters inside. This
will ease adding more per-cpu fields. No functional changes.

Signed-off-by: Tejun Heo <tj@...nel.org>
---
 kernel/sched/ext.c          | 18 +++++++++---------
 kernel/sched/ext_internal.h | 17 ++++++++++-------
 2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 7e15e852370c..701ca239ad00 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -635,7 +635,7 @@ static struct task_struct *scx_task_iter_next_locked(struct scx_task_iter *iter)
  * This can be used when preemption is not disabled.
  */
 #define scx_add_event(sch, name, cnt) do {					\
-	this_cpu_add((sch)->event_stats_cpu->name, (cnt));			\
+	this_cpu_add((sch)->pcpu->event_stats.name, (cnt));			\
 	trace_sched_ext_event(#name, (cnt));					\
 } while(0)
 
@@ -648,7 +648,7 @@ static struct task_struct *scx_task_iter_next_locked(struct scx_task_iter *iter)
  * This should be used only when preemption is disabled.
  */
 #define __scx_add_event(sch, name, cnt) do {					\
-	__this_cpu_add((sch)->event_stats_cpu->name, (cnt));			\
+	__this_cpu_add((sch)->pcpu->event_stats.name, (cnt));			\
 	trace_sched_ext_event(#name, cnt);					\
 } while(0)
 
@@ -3543,7 +3543,7 @@ static void scx_sched_free_rcu_work(struct work_struct *work)
 	int node;
 
 	kthread_stop(sch->helper->task);
-	free_percpu(sch->event_stats_cpu);
+	free_percpu(sch->pcpu);
 
 	for_each_node_state(node, N_POSSIBLE)
 		kfree(sch->global_dsqs[node]);
@@ -4444,13 +4444,13 @@ static struct scx_sched *scx_alloc_and_add_sched(struct sched_ext_ops *ops)
 		sch->global_dsqs[node] = dsq;
 	}
 
-	sch->event_stats_cpu = alloc_percpu(struct scx_event_stats);
-	if (!sch->event_stats_cpu)
+	sch->pcpu = alloc_percpu(struct scx_sched_pcpu);
+	if (!sch->pcpu)
 		goto err_free_gdsqs;
 
 	sch->helper = kthread_run_worker(0, "sched_ext_helper");
 	if (!sch->helper)
-		goto err_free_event_stats;
+		goto err_free_pcpu;
 	sched_set_fifo(sch->helper->task);
 
 	atomic_set(&sch->exit_kind, SCX_EXIT_NONE);
@@ -4468,8 +4468,8 @@ static struct scx_sched *scx_alloc_and_add_sched(struct sched_ext_ops *ops)
 
 err_stop_helper:
 	kthread_stop(sch->helper->task);
-err_free_event_stats:
-	free_percpu(sch->event_stats_cpu);
+err_free_pcpu:
+	free_percpu(sch->pcpu);
 err_free_gdsqs:
 	for_each_node_state(node, N_POSSIBLE)
 		kfree(sch->global_dsqs[node]);
@@ -6493,7 +6493,7 @@ static void scx_read_events(struct scx_sched *sch, struct scx_event_stats *event
 	/* Aggregate per-CPU event counters into @events. */
 	memset(events, 0, sizeof(*events));
 	for_each_possible_cpu(cpu) {
-		e_cpu = per_cpu_ptr(sch->event_stats_cpu, cpu);
+		e_cpu = &per_cpu_ptr(sch->pcpu, cpu)->event_stats;
 		scx_agg_event(events, e_cpu, SCX_EV_SELECT_CPU_FALLBACK);
 		scx_agg_event(events, e_cpu, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
 		scx_agg_event(events, e_cpu, SCX_EV_DISPATCH_KEEP_LAST);
diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
index 76690ede8700..af4c054fb6f8 100644
--- a/kernel/sched/ext_internal.h
+++ b/kernel/sched/ext_internal.h
@@ -846,6 +846,15 @@ struct scx_event_stats {
 	s64		SCX_EV_BYPASS_ACTIVATE;
 };
 
+struct scx_sched_pcpu {
+	/*
+	 * The event counters are in a per-CPU variable to minimize the
+	 * accounting overhead. A system-wide view on the event counter is
+	 * constructed when requested by scx_bpf_events().
+	 */
+	struct scx_event_stats	event_stats;
+};
+
 struct scx_sched {
 	struct sched_ext_ops	ops;
 	DECLARE_BITMAP(has_op, SCX_OPI_END);
@@ -860,13 +869,7 @@ struct scx_sched {
 	 */
 	struct rhashtable	dsq_hash;
 	struct scx_dispatch_q	**global_dsqs;
-
-	/*
-	 * The event counters are in a per-CPU variable to minimize the
-	 * accounting overhead. A system-wide view on the event counter is
-	 * constructed when requested by scx_bpf_events().
-	 */
-	struct scx_event_stats __percpu *event_stats_cpu;
+	struct scx_sched_pcpu __percpu *pcpu;
 
 	bool			warned_zero_slice;
 
-- 
2.51.0