[PATCH v3 4/5] sched: Add task enqueue/dequeue trace points
From: Nam Cao <hidden>
Date: 2025-08-11 08:41:02
Also in:
lkml
Subsystem:
scheduler, the rest, tracing · Maintainers:
Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
Add trace points into enqueue_task() and dequeue_task(). They are useful to implement RV monitor which validates RT scheduling. Signed-off-by: Nam Cao <redacted> --- Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Ben Segall <bsegall@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Valentin Schneider <vschneid@redhat.com> Cc: K Prateek Nayak <kprateek.nayak@amd.com> --- v3: fix up build issue on !SMP v2: Move the tracepoints to cover all task enqueue/dequeue, not just RT --- include/trace/events/sched.h | 13 +++++++++++++ kernel/sched/core.c | 8 +++++++- 2 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 7b2645b50e78..696d22af5a98 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h@@ -896,6 +896,19 @@ DECLARE_TRACE(sched_set_need_resched, TP_PROTO(struct task_struct *tsk, int cpu, int tif), TP_ARGS(tsk, cpu, tif)); +/* + * The two trace points below may not work as expected for fair tasks due + * to delayed dequeue. See: + * https://lore.kernel.org/lkml/179674c6-f82a-4718-ace2-67b5e672fdee@amd.com/ + */ +DECLARE_TRACE(enqueue_task, + TP_PROTO(int cpu, struct task_struct *task), + TP_ARGS(cpu, task)); + +DECLARE_TRACE(dequeue_task, + TP_PROTO(int cpu, struct task_struct *task), + TP_ARGS(cpu, task)); + #endif /* _TRACE_SCHED_H */ /* This part must be outside protection */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index be00629f0ba4..6367799aa023 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c@@ -2077,6 +2077,8 @@ unsigned long get_wchan(struct task_struct *p) void enqueue_task(struct rq *rq, struct task_struct *p, int flags) { + trace_enqueue_task_tp(cpu_of(rq), p); + if (!(flags & ENQUEUE_NOCLOCK)) update_rq_clock(rq);
@@ -2119,7 +2121,11 @@ inline bool dequeue_task(struct rq *rq, struct task_struct *p, int flags) * and mark the task ->sched_delayed. */ uclamp_rq_dec(rq, p); - return p->sched_class->dequeue_task(rq, p, flags); + if (p->sched_class->dequeue_task(rq, p, flags)) { + trace_dequeue_task_tp(cpu_of(rq), p); + return true; + } + return false; } void activate_task(struct rq *rq, struct task_struct *p, int flags)
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2.39.5