[PATCH 3/3] sched_ext: Add SCX_EV_ENQ_SKIP_MIGRATION_DISABLED

[Tejun Heo <tj@kernel.org>]

Count the number of times a migration disabled task is automatically
dispatched to its local DSQ.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 kernel/sched/ext.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 310db8484b77..b2378e29f45a 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1483,6 +1483,13 @@ struct scx_event_stats {
 	 */
 	u64		SCX_EV_ENQ_SKIP_EXITING;
 
+	/*
+	 * If SCX_OPS_ENQ_MIGRATION_DISABLED is not set, the number of times a
+	 * migration disabled task skips ops.enqueue() and is dispatched to its
+	 * local DSQ.
+	 */
+	u64		SCX_EV_ENQ_SKIP_MIGRATION_DISABLED;
+
 	/*
 	 * The total number of tasks enqueued (or pick_task-ed) with a
 	 * default time slice (SCX_SLICE_DFL).
@@ -2119,8 +2126,10 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 
 	/* see %SCX_OPS_ENQ_MIGRATION_DISABLED */
 	if (!static_branch_unlikely(&scx_ops_enq_migration_disabled) &&
-	    is_migration_disabled(p))
+	    is_migration_disabled(p)) {
+		__scx_add_event(SCX_EV_ENQ_SKIP_MIGRATION_DISABLED, 1);
 		goto local;
+	}
 
 	if (!SCX_HAS_OP(enqueue))
 		goto global;
@@ -5067,6 +5076,7 @@ static void scx_dump_state(struct scx_exit_info *ei, size_t dump_len)
 	scx_dump_event(s, &events, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
 	scx_dump_event(s, &events, SCX_EV_DISPATCH_KEEP_LAST);
 	scx_dump_event(s, &events, SCX_EV_ENQ_SKIP_EXITING);
+	scx_dump_event(s, &events, SCX_EV_ENQ_SKIP_MIGRATION_DISABLED);
 	scx_dump_event(s, &events, SCX_EV_ENQ_SLICE_DFL);
 	scx_dump_event(s, &events, SCX_EV_BYPASS_DURATION);
 	scx_dump_event(s, &events, SCX_EV_BYPASS_DISPATCH);
@@ -7210,6 +7220,7 @@ __bpf_kfunc void scx_bpf_events(struct scx_event_stats *events,
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_DISPATCH_KEEP_LAST);
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_ENQ_SKIP_EXITING);
+		scx_agg_event(&e_sys, e_cpu, SCX_EV_ENQ_SKIP_MIGRATION_DISABLED);
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_ENQ_SLICE_DFL);
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_BYPASS_DURATION);
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_BYPASS_DISPATCH);
-- 
2.48.1