linux-kernel - [PATCH 5/7] sched_ext: Add an event, SCX_EVENT_RQ_BYPASSING

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Message-ID: <20250116151543.80163-6-changwoo@igalia.com>
Date: Fri, 17 Jan 2025 00:15:41 +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 5/7] sched_ext: Add an event, SCX_EVENT_RQ_BYPASSING_OPS

Add a core event, SCX_EVENT_RQ_BYPASSING_OPS, which represents how many
operations are bypassed once the bypass mode is set.

Signed-off-by: Changwoo Min <changwoo@...lia.com>
---
 kernel/sched/ext.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 094e19f5fb78..44b44d963a0c 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1485,6 +1485,11 @@ struct scx_event_stat {
 	 * is dispatched to a local DSQ when exiting.
 	 */
 	u64		ENQ_LOCAL_EXITING;
+
+	/*
+	 * When the bypassing mode is set, the number of bypassed operations.
+	 */
+	u64		RQ_BYPASSING_OPS;
 };
 
 #define SCX_EVENT_IDX(e)	(offsetof(struct scx_event_stat, e)/sizeof(u64))
@@ -1500,6 +1505,7 @@ enum scx_event_kind {
 	SCX_EVENT_DEFINE(OFFLINE_LOCAL_DSQ),
 	SCX_EVENT_DEFINE(CNTD_RUN_WO_ENQ),
 	SCX_EVENT_DEFINE(ENQ_LOCAL_EXITING),
+	SCX_EVENT_DEFINE(RQ_BYPASSING_OPS),
 	SCX_EVENT_END = SCX_EVENT_END_IDX(),
 };
 
@@ -1508,6 +1514,7 @@ static const char *scx_event_stat_str[] = {
 	[SCX_EVENT_OFFLINE_LOCAL_DSQ]	= "offline_local_dsq",
 	[SCX_EVENT_CNTD_RUN_WO_ENQ]	= "cntd_run_wo_enq",
 	[SCX_EVENT_ENQ_LOCAL_EXITING]	= "enq_local_exiting",
+	[SCX_EVENT_RQ_BYPASSING_OPS]	= "rq_bypassing_ops",
 };
 
 /*
@@ -2087,8 +2094,10 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 	if (!scx_rq_online(rq))
 		goto local;
 
-	if (scx_rq_bypassing(rq))
+	if (scx_rq_bypassing(rq)) {
+		scx_add_event(RQ_BYPASSING_OPS, 1);
 		goto global;
+	}
 
 	if (p->scx.ddsp_dsq_id != SCX_DSQ_INVALID)
 		goto direct;
@@ -2933,6 +2942,8 @@ static int balance_one(struct rq *rq, struct task_struct *prev)
 	     scx_rq_bypassing(rq))) {
 		rq->scx.flags |= SCX_RQ_BAL_KEEP;
 		scx_add_event(CNTD_RUN_WO_ENQ, 1);
+		if (scx_rq_bypassing(rq))
+			scx_add_event(RQ_BYPASSING_OPS, 1);
 		goto has_tasks;
 	}
 	rq->scx.flags &= ~SCX_RQ_IN_BALANCE;
@@ -3708,6 +3719,9 @@ static int select_task_rq_scx(struct task_struct *p, int prev_cpu, int wake_flag
 			p->scx.slice = SCX_SLICE_DFL;
 			p->scx.ddsp_dsq_id = SCX_DSQ_LOCAL;
 		}
+
+		if (scx_rq_bypassing(task_rq(p)))
+			scx_add_event(RQ_BYPASSING_OPS, 1);
 		return cpu;
 	}
 }
@@ -3799,6 +3813,8 @@ void __scx_update_idle(struct rq *rq, bool idle, bool do_notify)
 	 */
 	if (SCX_HAS_OP(update_idle) && do_notify && !scx_rq_bypassing(rq))
 		SCX_CALL_OP(SCX_KF_REST, update_idle, cpu_of(rq), idle);
+	else if (scx_rq_bypassing(rq))
+		scx_add_event(RQ_BYPASSING_OPS, 1);
 
 	/*
 	 * Update the idle masks:
@@ -3940,6 +3956,7 @@ static void task_tick_scx(struct rq *rq, struct task_struct *curr, int queued)
 	if (scx_rq_bypassing(rq)) {
 		curr->scx.slice = 0;
 		touch_core_sched(rq, curr);
+		scx_add_event(RQ_BYPASSING_OPS, 1);
 	} else if (SCX_HAS_OP(tick)) {
 		SCX_CALL_OP(SCX_KF_REST, tick, curr);
 	}
@@ -7131,8 +7148,10 @@ __bpf_kfunc void scx_bpf_kick_cpu(s32 cpu, u64 flags)
 	 * lead to irq_work_queue() malfunction such as infinite busy wait for
 	 * IRQ status update. Suppress kicking.
 	 */
-	if (scx_rq_bypassing(this_rq))
+	if (scx_rq_bypassing(this_rq)) {
+		scx_add_event(RQ_BYPASSING_OPS, 1);
 		goto out;
+	}
 
 	/*
 	 * Actual kicking is bounced to kick_cpus_irq_workfn() to avoid nesting
-- 
2.48.1