sched/fair: Update comments in enqueue/dequeue_entity()

When reading the sched_avg related code, I found the comments in
enqueue/dequeue_entity() are not updated with the current code.

We don't add/subtract entity's runnable_avg from cfs_rq->runnable_avg
during enqueue/dequeue_entity(), those are done only for attach/detach.

This patch updates the comments to reflect the current code working.
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20220818124805.601-5-zhouchengming@bytedance.com

kernel/sched/fair.c

@@ -4434,7 +4434,8 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
 	/*
 	 * When enqueuing a sched_entity, we must:
 	 *   - Update loads to have both entity and cfs_rq synced with now.
-	 *   - Add its load to cfs_rq->runnable_avg
+	 *   - For group_entity, update its runnable_weight to reflect the new
+	 *     h_nr_running of its group cfs_rq.
 	 *   - For group_entity, update its weight to reflect the new share of
 	 *     its group cfs_rq
 	 *   - Add its new weight to cfs_rq->load.weight
@@ -4519,7 +4520,8 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
 	/*
 	 * When dequeuing a sched_entity, we must:
 	 *   - Update loads to have both entity and cfs_rq synced with now.
-	 *   - Subtract its load from the cfs_rq->runnable_avg.
+	 *   - For group_entity, update its runnable_weight to reflect the new
+	 *     h_nr_running of its group cfs_rq.
 	 *   - Subtract its previous weight from cfs_rq->load.weight.
 	 *   - For group entity, update its weight to reflect the new share
 	 *     of its group cfs_rq.