[PATCH v6 12/16] sched: Add deadline tracepoints

[Gabriele Monaco <gmonaco@redhat.com>]

Add the following tracepoints:

* sched_dl_throttle(dl_se, cpu, type):
    Called when a deadline entity is throttled
* sched_dl_replenish(dl_se, cpu, type):
    Called when a deadline entity's runtime is replenished
* sched_dl_update(dl_se, cpu, type):
    Called when a deadline entity updates without throttle or replenish
* sched_dl_server_start(dl_se, cpu, type):
    Called when a deadline server is started
* sched_dl_server_stop(dl_se, cpu, type):
    Called when a deadline server is stopped

Those tracepoints can be useful to validate the deadline scheduler with
RV and are not exported to tracefs.

Reviewed-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
---

Notes:
    V6:
    * Add dl_se type to differentiate between fair and ext servers
    * Add event to track dl_update_curr not firing other events
    V3:
    * Rename dl argument to dl_se in tracepoints

 include/trace/events/sched.h | 26 ++++++++++++++++++++++++++
 kernel/sched/core.c          |  4 ++++
 kernel/sched/deadline.c      | 25 ++++++++++++++++++++++++-
 3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 5844147ec5fd..944d65750a64 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -904,6 +904,32 @@ DECLARE_TRACE(sched_dequeue,
 	TP_PROTO(struct task_struct *tsk, int cpu),
 	TP_ARGS(tsk, cpu));
 
+#define DL_OTHER 0
+#define DL_TASK 1
+#define DL_SERVER_FAIR 2
+#define DL_SERVER_EXT 3
+
+DECLARE_TRACE(sched_dl_throttle,
+	TP_PROTO(struct sched_dl_entity *dl_se, int cpu, uint8_t type),
+	TP_ARGS(dl_se, cpu, type));
+
+DECLARE_TRACE(sched_dl_replenish,
+	TP_PROTO(struct sched_dl_entity *dl_se, int cpu, uint8_t type),
+	TP_ARGS(dl_se, cpu, type));
+
+/* Call to update_curr_dl_se not involving throttle or replenish */
+DECLARE_TRACE(sched_dl_update,
+	TP_PROTO(struct sched_dl_entity *dl_se, int cpu, uint8_t type),
+	TP_ARGS(dl_se, cpu, type));
+
+DECLARE_TRACE(sched_dl_server_start,
+	TP_PROTO(struct sched_dl_entity *dl_se, int cpu, uint8_t type),
+	TP_ARGS(dl_se, cpu, type));
+
+DECLARE_TRACE(sched_dl_server_stop,
+	TP_PROTO(struct sched_dl_entity *dl_se, int cpu, uint8_t type),
+	TP_ARGS(dl_se, cpu, type));
+
 #endif /* _TRACE_SCHED_H */
 
 /* This part must be outside protection */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4ca79ff58fca..b5bb2eb112bf 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -124,6 +124,10 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(sched_exit_tp);
 EXPORT_TRACEPOINT_SYMBOL_GPL(sched_set_need_resched_tp);
 EXPORT_TRACEPOINT_SYMBOL_GPL(sched_enqueue_tp);
 EXPORT_TRACEPOINT_SYMBOL_GPL(sched_dequeue_tp);
+EXPORT_TRACEPOINT_SYMBOL_GPL(sched_dl_throttle_tp);
+EXPORT_TRACEPOINT_SYMBOL_GPL(sched_dl_replenish_tp);
+EXPORT_TRACEPOINT_SYMBOL_GPL(sched_dl_server_start_tp);
+EXPORT_TRACEPOINT_SYMBOL_GPL(sched_dl_server_stop_tp);
 
 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
 DEFINE_PER_CPU(struct rnd_state, sched_rnd_state);
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index d08b00429323..b8d01f0eda7d 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -115,6 +115,20 @@ static inline bool is_dl_boosted(struct sched_dl_entity *dl_se)
 }
 #endif /* !CONFIG_RT_MUTEXES */
 
+static inline uint8_t dl_get_type(struct sched_dl_entity *dl_se,
+				       struct rq *rq)
+{
+	if (!dl_server(dl_se))
+		return DL_TASK;
+	if (dl_se == &rq->fair_server)
+		return DL_SERVER_FAIR;
+#ifdef CONFIG_SCHED_CLASS_EXT
+	if (dl_se == &rq->ext_server)
+		return DL_SERVER_EXT;
+#endif
+	return DL_OTHER;
+}
+
 static inline struct dl_bw *dl_bw_of(int i)
 {
 	RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
@@ -733,6 +747,7 @@ static inline void replenish_dl_new_period(struct sched_dl_entity *dl_se,
 		dl_se->dl_throttled = 1;
 		dl_se->dl_defer_armed = 1;
 	}
+	trace_sched_dl_replenish_tp(dl_se, cpu_of(rq), dl_get_type(dl_se, rq));
 }
 
 /*
@@ -848,6 +863,8 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se)
 	if (dl_se->dl_throttled)
 		dl_se->dl_throttled = 0;
 
+	trace_sched_dl_replenish_tp(dl_se, cpu_of(rq), dl_get_type(dl_se, rq));
+
 	/*
 	 * If this is the replenishment of a deferred reservation,
 	 * clear the flag and return.
@@ -1345,6 +1362,7 @@ static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se)
 	    dl_time_before(rq_clock(rq), dl_next_period(dl_se))) {
 		if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(dl_se)))
 			return;
+		trace_sched_dl_throttle_tp(dl_se, cpu_of(rq), dl_get_type(dl_se, rq));
 		dl_se->dl_throttled = 1;
 		if (dl_se->runtime > 0)
 			dl_se->runtime = 0;
@@ -1508,6 +1526,7 @@ static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64
 
 throttle:
 	if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) {
+		trace_sched_dl_throttle_tp(dl_se, cpu_of(rq), dl_get_type(dl_se, rq));
 		dl_se->dl_throttled = 1;
 
 		/* If requested, inform the user about runtime overruns. */
@@ -1532,7 +1551,8 @@ static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64
 
 		if (!is_leftmost(dl_se, &rq->dl))
 			resched_curr(rq);
-	}
+	} else
+		trace_sched_dl_update_tp(dl_se, cpu_of(rq), dl_get_type(dl_se, rq));
 
 	/*
 	 * The dl_server does not account for real-time workload because it
@@ -1810,6 +1830,7 @@ void dl_server_start(struct sched_dl_entity *dl_se)
 	if (WARN_ON_ONCE(!cpu_online(cpu_of(rq))))
 		return;
 
+	trace_sched_dl_server_start_tp(dl_se, cpu_of(rq), dl_get_type(dl_se, rq));
 	dl_se->dl_server_active = 1;
 	enqueue_dl_entity(dl_se, ENQUEUE_WAKEUP);
 	if (!dl_task(dl_se->rq->curr) || dl_entity_preempt(dl_se, &rq->curr->dl))
@@ -1821,6 +1842,8 @@ void dl_server_stop(struct sched_dl_entity *dl_se)
 	if (!dl_server(dl_se) || !dl_server_active(dl_se))
 		return;
 
+	trace_sched_dl_server_stop_tp(dl_se, cpu_of(dl_se->rq),
+				      dl_get_type(dl_se, dl_se->rq));
 	dequeue_dl_entity(dl_se, DEQUEUE_SLEEP);
 	hrtimer_try_to_cancel(&dl_se->dl_timer);
 	dl_se->dl_defer_armed = 0;
-- 
2.53.0