linux-kernel - [PATCH v2 09/11] sched_ext: Add an event, BYPASS

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Message-ID: <20250126101614.232388-10-changwoo@igalia.com>
Date: Sun, 26 Jan 2025 19:16:12 +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 09/11] sched_ext: Add an event, BYPASS_DURATION

Add a core event, BYPASS_DURATION, which represents the total duration
of bypass modes in nanoseconds.

Signed-off-by: Changwoo Min <changwoo@...lia.com>
---
 kernel/sched/ext.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 9a680774c1fc..c71c89cfd1c8 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1486,6 +1486,11 @@ struct scx_event_stats {
 	 */
 	u64		ENQ_SKIP_EXITING;
 
+	/*
+	 * The total duration of bypass modes in nanoseconds.
+	 */
+	u64		BYPASS_DURATION;
+
 	/*
 	 * The number of tasks dispatched in the bypassing mode.
 	 */
@@ -1547,6 +1552,12 @@ static DEFINE_PER_CPU(struct scx_event_stats, event_stats_cpu);
 } while (0)
 
 
+/*
+ * The last time the bypass mode started.
+ * This is used to measure BYPASS_DURATION.
+ */
+static unsigned long scx_bypass_timestamp;
+
 static void scx_bpf_event_stats(struct scx_event_stats *events, size_t events__sz);
 
 static enum scx_ops_enable_state scx_ops_enable_state(void)
@@ -4935,12 +4946,15 @@ static void scx_ops_bypass(bool bypass)
 		WARN_ON_ONCE(scx_ops_bypass_depth <= 0);
 		if (scx_ops_bypass_depth != 1)
 			goto unlock;
+		scx_bypass_timestamp = ktime_get_ns();
 		scx_add_event(BYPASS_ACTIVATE, 1);
 	} else {
 		scx_ops_bypass_depth--;
 		WARN_ON_ONCE(scx_ops_bypass_depth < 0);
 		if (scx_ops_bypass_depth != 0)
 			goto unlock;
+		scx_add_event(BYPASS_DURATION,
+			      ktime_get_ns() - scx_bypass_timestamp);
 	}
 
 	atomic_inc(&scx_ops_breather_depth);
@@ -5531,6 +5545,7 @@ static void scx_dump_state(struct scx_exit_info *ei, size_t dump_len)
 	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);
+	scx_dump_event(s, &events, BYPASS_DURATION);
 	scx_dump_event(s, &events, BYPASS_DISPATCH);
 	scx_dump_event(s, &events, BYPASS_ACTIVATE);
 
@@ -7864,6 +7879,7 @@ __bpf_kfunc void scx_bpf_event_stats(struct scx_event_stats *events,
 		scx_agg_event(&e_sys, e_cpu, SELECT_CPU_FALLBACK);
 		scx_agg_event(&e_sys, e_cpu, DISPATCH_LOCAL_DSQ_OFFLINE);
 		scx_agg_event(&e_sys, e_cpu, DISPATCH_KEEP_LAST);
+		scx_agg_event(&e_sys, e_cpu, BYPASS_DURATION);
 		scx_agg_event(&e_sys, e_cpu, BYPASS_DISPATCH);
 		scx_agg_event(&e_sys, e_cpu, BYPASS_ACTIVATE);
 	}
-- 
2.48.1