sched/debug: Add new tracepoints to track PELT at rq level

The new tracepoints allow tracking PELT signals at rq level for all
scheduling classes + irq.
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-4-qais.yousef@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

include/trace/events/sched.h

@@ -594,6 +594,29 @@ TRACE_EVENT(sched_wake_idle_without_ipi,
 
 	TP_printk("cpu=%d", __entry->cpu)
 );
+
+/*
+ * Following tracepoints are not exported in tracefs and provide hooking
+ * mechanisms only for testing and debugging purposes.
+ *
+ * Postfixed with _tp to make them easily identifiable in the code.
+ */
+DECLARE_TRACE(pelt_cfs_tp,
+	TP_PROTO(struct cfs_rq *cfs_rq),
+	TP_ARGS(cfs_rq));
+
+DECLARE_TRACE(pelt_rt_tp,
+	TP_PROTO(struct rq *rq),
+	TP_ARGS(rq));
+
+DECLARE_TRACE(pelt_dl_tp,
+	TP_PROTO(struct rq *rq),
+	TP_ARGS(rq));
+
+DECLARE_TRACE(pelt_irq_tp,
+	TP_PROTO(struct rq *rq),
+	TP_ARGS(rq));
+
 #endif /* _TRACE_SCHED_H */
 
 /* This part must be outside protection */

kernel/sched/fair.c

@@ -3347,6 +3347,8 @@ static inline int propagate_entity_load_avg(struct sched_entity *se)
 	update_tg_cfs_util(cfs_rq, se, gcfs_rq);
 	update_tg_cfs_runnable(cfs_rq, se, gcfs_rq);
 
+	trace_pelt_cfs_tp(cfs_rq);
+
 	return 1;
 }
 
@@ -3499,6 +3501,8 @@ static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
 	add_tg_cfs_propagate(cfs_rq, se->avg.load_sum);
 
 	cfs_rq_util_change(cfs_rq, flags);
+
+	trace_pelt_cfs_tp(cfs_rq);
 }
 
 /**
@@ -3518,6 +3522,8 @@ static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
 	add_tg_cfs_propagate(cfs_rq, -se->avg.load_sum);
 
 	cfs_rq_util_change(cfs_rq, 0);
+
+	trace_pelt_cfs_tp(cfs_rq);
 }
 
 /*

kernel/sched/pelt.c

@@ -28,6 +28,8 @@
 #include "sched.h"
 #include "pelt.h"
 
+#include <trace/events/sched.h>
+
 /*
  * Approximate:
  *   val * y^n,    where y^32 ~= 0.5 (~1 scheduling period)
@@ -292,6 +294,7 @@ int __update_load_avg_cfs_rq(u64 now, struct cfs_rq *cfs_rq)
 				cfs_rq->curr != NULL)) {
 
 		___update_load_avg(&cfs_rq->avg, 1, 1);
+		trace_pelt_cfs_tp(cfs_rq);
 		return 1;
 	}
 
@@ -317,6 +320,7 @@ int update_rt_rq_load_avg(u64 now, struct rq *rq, int running)
 				running)) {
 
 		___update_load_avg(&rq->avg_rt, 1, 1);
+		trace_pelt_rt_tp(rq);
 		return 1;
 	}
 
@@ -340,6 +344,7 @@ int update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
 				running)) {
 
 		___update_load_avg(&rq->avg_dl, 1, 1);
+		trace_pelt_dl_tp(rq);
 		return 1;
 	}
 
@@ -388,8 +393,10 @@ int update_irq_load_avg(struct rq *rq, u64 running)
 				1,
 				1);
 
-	if (ret)
+	if (ret) {
 		___update_load_avg(&rq->avg_irq, 1, 1);
+		trace_pelt_irq_tp(rq);
+	}
 
 	return ret;
 }