[PATCH v2 1/4] block, bfq: add support to track if root_group have any pending requests

[Yu Kuai <yukuai3@huawei.com>]

Add a new member in bfq_data to track number of queues that are in
root_group with any pending requests. This will be used in next patch
to optmize queue idle judgment when root_group doesn't have any
pending requests.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 block/bfq-iosched.c |  8 +++++++-
 block/bfq-iosched.h | 13 +++++++++++--
 block/bfq-wf2q.c    | 37 ++++++++++++++++++++++++-------------
 3 files changed, 42 insertions(+), 16 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 727955918563..7c6b412f9a9c 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -859,8 +859,14 @@ void __bfq_weights_tree_remove(struct bfq_data *bfqd,
 void bfq_weights_tree_remove(struct bfq_data *bfqd,
 			     struct bfq_queue *bfqq)
 {
-	struct bfq_entity *entity = bfqq->entity.parent;
+	struct bfq_entity *entity = &bfqq->entity;
+
+	if (entity->in_groups_with_pending_reqs) {
+		entity->in_groups_with_pending_reqs = false;
+		bfqd->num_queues_with_pending_reqs_in_root--;
+	}
 
+	entity = entity->parent;
 	for_each_entity(entity) {
 		struct bfq_sched_data *sd = entity->my_sched_data;
 
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 99c2a3cb081e..610769214f72 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -195,7 +195,12 @@ struct bfq_entity {
 	/* flag, set to request a weight, ioprio or ioprio_class change  */
 	int prio_changed;
 
-	/* flag, set if the entity is counted in groups_with_pending_reqs */
+	/*
+	 * If entity represents bfq_group, this flag will set if the group is
+	 * not root_group and have any pending requests; If entity represents
+	 * bfq_queue, this flag will set if the queue is in root_group and have
+	 * any pending requests.
+	 */
 	bool in_groups_with_pending_reqs;
 
 	/* last child queue of entity created (for non-leaf entities) */
@@ -539,7 +544,11 @@ struct bfq_data {
 	 * with no request waiting for completion.
 	 */
 	unsigned int num_groups_with_pending_reqs;
-
+	/*
+	 * number of queues that are in root_group with at least one request
+	 * waiting for completion.
+	 */
+	unsigned int num_queues_with_pending_reqs_in_root;
 	/*
 	 * Per-class (RT, BE, IDLE) number of bfq_queues containing
 	 * requests (including the queue in service, even if it is
diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 7a462df71f68..188c8f907219 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -946,6 +946,29 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
 	bfq_active_insert(st, entity);
 }
 
+static void bfq_update_groups_with_pending_reqs(struct bfq_entity *entity)
+{
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+	if (bfqq) {
+		if (!entity->parent && !entity->in_groups_with_pending_reqs) {
+			entity->in_groups_with_pending_reqs = true;
+			bfqq->bfqd->num_queues_with_pending_reqs_in_root++;
+		}
+	} else {
+		if (!entity->in_groups_with_pending_reqs) {
+			struct bfq_group *bfqg =
+				container_of(entity, struct bfq_group, entity);
+			struct bfq_data *bfqd = bfqg->bfqd;
+
+			entity->in_groups_with_pending_reqs = true;
+			bfqd->num_groups_with_pending_reqs++;
+		}
+	}
+#endif
+}
+
 /**
  * __bfq_activate_entity - handle activation of entity.
  * @entity: the entity being activated.
@@ -999,19 +1022,7 @@ static void __bfq_activate_entity(struct bfq_entity *entity,
 		entity->on_st_or_in_serv = true;
 	}
 
-#ifdef CONFIG_BFQ_GROUP_IOSCHED
-	if (!bfq_entity_to_bfqq(entity)) { /* bfq_group */
-		struct bfq_group *bfqg =
-			container_of(entity, struct bfq_group, entity);
-		struct bfq_data *bfqd = bfqg->bfqd;
-
-		if (!entity->in_groups_with_pending_reqs) {
-			entity->in_groups_with_pending_reqs = true;
-			bfqd->num_groups_with_pending_reqs++;
-		}
-	}
-#endif
-
+	bfq_update_groups_with_pending_reqs(entity);
 	bfq_update_fin_time_enqueue(entity, st, backshifted);
 }
 
-- 
2.31.1