On 2021/08/27 1:00, Paolo Valente wrote:

Why do you make these extensive changes, while you can leave all the
function unchanged and just modify the above condition to something
like

|| bfqd->num_groups_with_pending_reqs > 1
|| (bfqd->num_groups_with_pending_reqs && bfqd->num_queues_with_pending_reqs_in_root)

Hi, Paolo

I was thinking that if CONFIG_BFQ_GROUP_IOSCHED is enabled, there is no
need to caculate smallest_weight, varied_queue_weights, and
multiple_classes_busy:

If we count root group into num_groups_with_pending_reqs
  - If num_groups_with_pending_reqs <= 1, idle is not needed
  - If num_groups_with_pending_reqs  > 1, idle is needed

Thus such changes can save some additional overhead.

Thanks
Yu Kuai

In addition, I still wonder whether you can simply add also the root
group to bfqd->num_groups_with_pending_reqs (when the root group is
active).  This would make the design much cleaner.

Thanks,
Paolo

quoted

-#endif
-		;
+	return varied_queue_weights || multiple_classes_busy;
}

/*
-- 
2.31.1

.