sched/fair: Explicitly generate __update_load_avg() instances

The __update_load_avg() function is an __always_inline because its
used with constant propagation to generate different variants of the
code without having to duplicate it (which would be prone to bugs).

Explicitly instantiate the 3 variants.

Note that most of this is called from rather hot paths, so reducing
branches is good.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

@@ -2849,7 +2849,7 @@ static u32 __compute_runnable_contrib(u64 n)
  *            = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
  */
 static __always_inline int
-__update_load_avg(u64 now, int cpu, struct sched_avg *sa,
+___update_load_avg(u64 now, int cpu, struct sched_avg *sa,
 		  unsigned long weight, int running, struct cfs_rq *cfs_rq)
 {
 	u64 delta, scaled_delta, periods;
@@ -2953,6 +2953,28 @@ __update_load_avg(u64 now, int cpu, struct sched_avg *sa,
 	return decayed;
 }
 
+static int
+__update_load_avg_blocked_se(u64 now, int cpu, struct sched_entity *se)
+{
+	return ___update_load_avg(now, cpu, &se->avg, 0, 0, NULL);
+}
+
+static int
+__update_load_avg_se(u64 now, int cpu, struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	return ___update_load_avg(now, cpu, &se->avg,
+				  se->on_rq * scale_load_down(se->load.weight),
+				  cfs_rq->curr == se, NULL);
+}
+
+static int
+__update_load_avg_cfs_rq(u64 now, int cpu, struct cfs_rq *cfs_rq)
+{
+	return ___update_load_avg(now, cpu, &cfs_rq->avg,
+			scale_load_down(cfs_rq->load.weight),
+			cfs_rq->curr != NULL, cfs_rq);
+}
+
 /*
  * Signed add and clamp on underflow.
  *
@@ -3014,6 +3036,9 @@ static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force)
 void set_task_rq_fair(struct sched_entity *se,
 		      struct cfs_rq *prev, struct cfs_rq *next)
 {
+	u64 p_last_update_time;
+	u64 n_last_update_time;
+
 	if (!sched_feat(ATTACH_AGE_LOAD))
 		return;
 
@@ -3024,11 +3049,11 @@ void set_task_rq_fair(struct sched_entity *se,
 	 * time. This will result in the wakee task is less decayed, but giving
 	 * the wakee more load sounds not bad.
 	 */
-	if (se->avg.last_update_time && prev) {
-		u64 p_last_update_time;
-		u64 n_last_update_time;
+	if (!(se->avg.last_update_time && prev))
+		return;
 
 #ifndef CONFIG_64BIT
+	{
 		u64 p_last_update_time_copy;
 		u64 n_last_update_time_copy;
 
@@ -3043,14 +3068,13 @@ void set_task_rq_fair(struct sched_entity *se,
 
 		} while (p_last_update_time != p_last_update_time_copy ||
 			 n_last_update_time != n_last_update_time_copy);
+	}
 #else
 	p_last_update_time = prev->avg.last_update_time;
 	n_last_update_time = next->avg.last_update_time;
 #endif
-		__update_load_avg(p_last_update_time, cpu_of(rq_of(prev)),
-				  &se->avg, 0, 0, NULL);
+	__update_load_avg_blocked_se(p_last_update_time, cpu_of(rq_of(prev)), se);
 	se->avg.last_update_time = n_last_update_time;
-	}
 }
 
 /* Take into account change of utilization of a child task group */
@@ -3295,8 +3319,7 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool update_freq)
 		set_tg_cfs_propagate(cfs_rq);
 	}
 
-	decayed = __update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa,
-		scale_load_down(cfs_rq->load.weight), cfs_rq->curr != NULL, cfs_rq);
+	decayed = __update_load_avg_cfs_rq(now, cpu_of(rq_of(cfs_rq)), cfs_rq);
 
 #ifndef CONFIG_64BIT
 	smp_wmb();
@@ -3328,11 +3351,8 @@ static inline void update_load_avg(struct sched_entity *se, int flags)
 	 * Track task load average for carrying it to new CPU after migrated, and
 	 * track group sched_entity load average for task_h_load calc in migration
 	 */
-	if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD)) {
-		__update_load_avg(now, cpu, &se->avg,
-			  se->on_rq * scale_load_down(se->load.weight),
-			  cfs_rq->curr == se, NULL);
-	}
+	if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
+		__update_load_avg_se(now, cpu, cfs_rq, se);
 
 	decayed  = update_cfs_rq_load_avg(now, cfs_rq, true);
 	decayed |= propagate_entity_load_avg(se);
@@ -3437,7 +3457,7 @@ void sync_entity_load_avg(struct sched_entity *se)
 	u64 last_update_time;
 
 	last_update_time = cfs_rq_last_update_time(cfs_rq);
-	__update_load_avg(last_update_time, cpu_of(rq_of(cfs_rq)), &se->avg, 0, 0, NULL);
+	__update_load_avg_blocked_se(last_update_time, cpu_of(rq_of(cfs_rq)), se);
 }
 
 /*