linux-kernel - [PATCH v2 06/11] sched_ext: Add an event, ENQ_SKIP

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Message-ID: <20250126101614.232388-7-changwoo@igalia.com>
Date: Sun, 26 Jan 2025 19:16:09 +0900
From: Changwoo Min <changwoo@...lia.com>
To: tj@...nel.org,
	void@...ifault.com,
	arighi@...dia.com
Cc: kernel-dev@...lia.com,
	linux-kernel@...r.kernel.org,
	Changwoo Min <changwoo@...lia.com>
Subject: [PATCH v2 06/11] sched_ext: Add an event, ENQ_SKIP_EXITING

Add a core event, ENQ_SKIP_EXITING, which represents how many times
a task is enqueued to a local DSQ when exiting if SCX_OPS_ENQ_EXITING
is not set.

__scx_add_event() is used since the caller holds an rq lock,
so the preemption has already been disabled.

Signed-off-by: Changwoo Min <changwoo@...lia.com>
---
 kernel/sched/ext.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index d3a1ef58202c..6dc86bc06596 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1479,6 +1479,12 @@ struct scx_event_stats {
 	 * continued to run because there were no other tasks on the CPU.
 	 */
 	u64		DISPATCH_KEEP_LAST;
+
+	/*
+	 * If SCX_OPS_ENQ_EXITING is not set, the number of times that a task
+	 * is dispatched to a local DSQ when exiting.
+	 */
+	u64		ENQ_SKIP_EXITING;
 };
 
 /*
@@ -2086,8 +2092,10 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 
 	/* see %SCX_OPS_ENQ_EXITING */
 	if (!static_branch_unlikely(&scx_ops_enq_exiting) &&
-	    unlikely(p->flags & PF_EXITING))
+	    unlikely(p->flags & PF_EXITING)) {
+		__scx_add_event(ENQ_SKIP_EXITING, 1);
 		goto local;
+	}
 
 	if (!SCX_HAS_OP(enqueue))
 		goto global;
@@ -5508,6 +5516,7 @@ static void scx_dump_state(struct scx_exit_info *ei, size_t dump_len)
 	scx_dump_event(s, &events, SELECT_CPU_FALLBACK);
 	scx_dump_event(s, &events, DISPATCH_LOCAL_DSQ_OFFLINE);
 	scx_dump_event(s, &events, DISPATCH_KEEP_LAST);
+	scx_dump_event(s, &events, ENQ_SKIP_EXITING);
 
 	if (seq_buf_has_overflowed(&s) && dump_len >= sizeof(trunc_marker))
 		memcpy(ei->dump + dump_len - sizeof(trunc_marker),
-- 
2.48.1