linux-kernel - [PATCH v2 2/3] blk-throttle: calling throtl_dequeue/enqueue

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Message-Id: <20220827101637.1775111-3-yukuai1@huaweicloud.com>
Date:   Sat, 27 Aug 2022 18:16:36 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     tj@...nel.org, axboe@...nel.dk
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 v2 2/3] blk-throttle: calling throtl_dequeue/enqueue_tg in pairs

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

It's a little weird to call throtl_dequeue_tg() unconditionally in
throtl_select_dispatch(), since it will be called in tg_update_disptime()
again if some bio is still throttled. Thus call it later if there are no
throttled bio. There are no functional changes.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
Acked-by: Tejun Heo <tj@...nel.org>
---
 block/blk-throttle.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index fe1fa6441105..64002435fa43 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1101,13 +1101,13 @@ static int throtl_select_dispatch(struct throtl_service_queue *parent_sq)
 		if (time_before(jiffies, tg->disptime))
 			break;
 
-		throtl_dequeue_tg(tg);
-
 		nr_disp += throtl_dispatch_tg(tg);
 
 		sq = &tg->service_queue;
 		if (sq->nr_queued[READ] || sq->nr_queued[WRITE])
 			tg_update_disptime(tg);
+		else
+			throtl_dequeue_tg(tg);
 
 		if (nr_disp >= THROTL_QUANTUM)
 			break;
-- 
2.31.1