sched,stats: Further simplify sched_info

There's no point doing delta==0 updates.
Suggested-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

kernel/sched/stats.h

@@ -160,10 +160,11 @@ static inline void sched_info_dequeue(struct rq *rq, struct task_struct *t)
 {
 	unsigned long long delta = 0;
 
-	if (t->sched_info.last_queued) {
+	if (!t->sched_info.last_queued)
+		return;
+
 	delta = rq_clock(rq) - t->sched_info.last_queued;
 	t->sched_info.last_queued = 0;
-	}
 	t->sched_info.run_delay += delta;
 
 	rq_sched_info_dequeue(rq, delta);
@@ -176,12 +177,14 @@ static inline void sched_info_dequeue(struct rq *rq, struct task_struct *t)
  */
 static void sched_info_arrive(struct rq *rq, struct task_struct *t)
 {
-	unsigned long long now = rq_clock(rq), delta = 0;
+	unsigned long long now, delta = 0;
 
-	if (t->sched_info.last_queued) {
+	if (!t->sched_info.last_queued)
+		return;
+
+	now = rq_clock(rq);
 	delta = now - t->sched_info.last_queued;
 	t->sched_info.last_queued = 0;
-	}
 	t->sched_info.run_delay += delta;
 	t->sched_info.last_arrival = now;
 	t->sched_info.pcount++;