linux-kernel - [PATCH v7 8/9] blk-throttle: cleanup tg_update

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Message-Id: <20220802140415.2960284-9-yukuai1@huaweicloud.com>
Date:   Tue,  2 Aug 2022 22:04:14 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     tj@...nel.org, mkoutny@...e.com, axboe@...nel.dk,
        ming.lei@...hat.com
Cc:     cgroups@...r.kernel.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, yukuai3@...wei.com,
        yukuai1@...weicloud.com, yi.zhang@...wei.com
Subject: [PATCH v7 8/9] blk-throttle: cleanup tg_update_disptime()

From: Yu Kuai <yukuai3@...wei.com>

tg_update_disptime() only need to adjust postion for 'tg' in
'parent_sq', there is no need to call throtl_enqueue/dequeue_tg().

Save a little overhead in tg_update_disptime() and prepare to cleanup
flag 'THROTL_TG_PENDING', there are no functional changes.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
 block/blk-throttle.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index f7048f87b19f..6b2096e95221 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -520,7 +520,6 @@ static void throtl_rb_erase(struct rb_node *n,
 {
 	rb_erase_cached(n, &parent_sq->pending_tree);
 	RB_CLEAR_NODE(n);
-	--parent_sq->nr_pending;
 }
 
 static void update_min_dispatch_time(struct throtl_service_queue *parent_sq)
@@ -572,7 +571,11 @@ static void throtl_enqueue_tg(struct throtl_grp *tg)
 static void throtl_dequeue_tg(struct throtl_grp *tg)
 {
 	if (tg->flags & THROTL_TG_PENDING) {
-		throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq);
+		struct throtl_service_queue *parent_sq =
+			tg->service_queue.parent_sq;
+
+		throtl_rb_erase(&tg->rb_node, parent_sq);
+		--parent_sq->nr_pending;
 		tg->flags &= ~THROTL_TG_PENDING;
 	}
 }
@@ -1045,9 +1048,9 @@ static void tg_update_disptime(struct throtl_grp *tg)
 	disptime = jiffies + min_wait;
 
 	/* Update dispatch time */
-	throtl_dequeue_tg(tg);
+	throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq);
 	tg->disptime = disptime;
-	throtl_enqueue_tg(tg);
+	tg_service_queue_add(tg);
 
 	/* see throtl_add_bio_tg() */
 	tg->flags &= ~THROTL_TG_WAS_EMPTY;
-- 
2.31.1