linux-kernel - [PATCH -next v10 2/4] block, bfq: record how many queues have pending requests

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Date:   Fri, 10 Jun 2022 10:16:59 +0800
From:   Yu Kuai <yukuai3@...wei.com>
To:     <paolo.valente@...aro.org>, <jack@...e.cz>,
        <cgroups@...r.kernel.org>, <linux-block@...r.kernel.org>
CC:     <tj@...nel.org>, <axboe@...nel.dk>, <linux-kernel@...r.kernel.org>,
        <yukuai3@...wei.com>, <yi.zhang@...wei.com>
Subject: [PATCH -next v10 2/4] block, bfq: record how many queues have pending requests

Prepare to refactor the counting of 'num_groups_with_pending_reqs'.

Add a counter in bfq_group, update it while tracking if bfqq have pending
requests and when bfq_bfqq_move() is called.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
Reviewed-by: Jan Kara <jack@...e.cz>
---
 block/bfq-cgroup.c  | 10 ++++++++++
 block/bfq-iosched.h |  1 +
 block/bfq-wf2q.c    | 12 ++++++++++--
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 09574af83566..88c0c320ddf3 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -557,6 +557,7 @@ static void bfq_pd_init(struct blkg_policy_data *pd)
 				   */
 	bfqg->bfqd = bfqd;
 	bfqg->active_entities = 0;
+	bfqg->num_queues_with_pending_reqs = 0;
 	bfqg->online = true;
 	bfqg->rq_pos_tree = RB_ROOT;
 }
@@ -646,6 +647,7 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 {
 	struct bfq_entity *entity = &bfqq->entity;
 	struct bfq_group *old_parent = bfqq_group(bfqq);
+	bool has_pending_reqs = false;
 
 	/*
 	 * No point to move bfqq to the same group, which can happen when
@@ -666,6 +668,11 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 	 */
 	bfqq->ref++;
 
+	if (entity->in_groups_with_pending_reqs) {
+		has_pending_reqs = true;
+		bfq_del_bfqq_in_groups_with_pending_reqs(bfqq);
+	}
+
 	/* If bfqq is empty, then bfq_bfqq_expire also invokes
 	 * bfq_del_bfqq_busy, thereby removing bfqq and its entity
 	 * from data structures related to current group. Otherwise we
@@ -693,6 +700,9 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 	/* pin down bfqg and its associated blkg  */
 	bfqg_and_blkg_get(bfqg);
 
+	if (has_pending_reqs)
+		bfq_add_bfqq_in_groups_with_pending_reqs(bfqq);
+
 	if (bfq_bfqq_busy(bfqq)) {
 		if (unlikely(!bfqd->nonrot_with_queueing))
 			bfq_pos_tree_add_move(bfqd, bfqq);
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 69c7d15417e5..de2446a9b7ab 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -943,6 +943,7 @@ struct bfq_group {
 	struct bfq_entity *my_entity;
 
 	int active_entities;
+	int num_queues_with_pending_reqs;
 
 	struct rb_root rq_pos_tree;
 
diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 5704a0315cf2..6f36f3fe5cc8 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -1651,16 +1651,24 @@ void bfq_add_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq)
 {
 	struct bfq_entity *entity = &bfqq->entity;
 
-	if (!entity->in_groups_with_pending_reqs)
+	if (!entity->in_groups_with_pending_reqs) {
 		entity->in_groups_with_pending_reqs = true;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+		bfqq_group(bfqq)->num_queues_with_pending_reqs++;
+#endif
+	}
 }
 
 void bfq_del_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq)
 {
 	struct bfq_entity *entity = &bfqq->entity;
 
-	if (entity->in_groups_with_pending_reqs)
+	if (entity->in_groups_with_pending_reqs) {
 		entity->in_groups_with_pending_reqs = false;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+		bfqq_group(bfqq)->num_queues_with_pending_reqs--;
+#endif
+	}
 }
 
 /*
-- 
2.31.1