linux-kernel - [PATCH AUTOSEL 6.12 194/486] blk-throttle: don't take carryover for prioritized processing of metadata

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Message-Id: <20250505223922.2682012-194-sashal@kernel.org>
Date: Mon,  5 May 2025 18:34:30 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Ming Lei <ming.lei@...hat.com>,
	Tejun Heo <tj@...nel.org>,
	Josef Bacik <josef@...icpanda.com>,
	Yu Kuai <yukuai3@...wei.com>,
	Jens Axboe <axboe@...nel.dk>,
	Sasha Levin <sashal@...nel.org>,
	cgroups@...r.kernel.org,
	linux-block@...r.kernel.org
Subject: [PATCH AUTOSEL 6.12 194/486] blk-throttle: don't take carryover for prioritized processing of metadata

From: Ming Lei <ming.lei@...hat.com>

[ Upstream commit a9fc8868b350cbf4ff730a4ea9651319cc669516 ]

Commit 29390bb5661d ("blk-throttle: support prioritized processing of metadata")
takes bytes/ios carryover for prioritized processing of metadata. Turns out
we can support it by charging it directly without trimming slice, and the
result is same with carryover.

Cc: Tejun Heo <tj@...nel.org>
Cc: Josef Bacik <josef@...icpanda.com>
Cc: Yu Kuai <yukuai3@...wei.com>
Signed-off-by: Ming Lei <ming.lei@...hat.com>
Acked-by: Tejun Heo <tj@...nel.org>
Link: https://lore.kernel.org/r/20250305043123.3938491-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 block/blk-throttle.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 2c4192e12efab..6b82fcbd7e774 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1593,13 +1593,6 @@ static bool tg_within_limit(struct throtl_grp *tg, struct bio *bio, bool rw)
 	return tg_may_dispatch(tg, bio, NULL);
 }
 
-static void tg_dispatch_in_debt(struct throtl_grp *tg, struct bio *bio, bool rw)
-{
-	if (!bio_flagged(bio, BIO_BPS_THROTTLED))
-		tg->carryover_bytes[rw] -= throtl_bio_data_size(bio);
-	tg->carryover_ios[rw]--;
-}
-
 bool __blk_throtl_bio(struct bio *bio)
 {
 	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
@@ -1636,10 +1629,12 @@ bool __blk_throtl_bio(struct bio *bio)
 			/*
 			 * IOs which may cause priority inversions are
 			 * dispatched directly, even if they're over limit.
-			 * Debts are handled by carryover_bytes/ios while
-			 * calculating wait time.
+			 *
+			 * Charge and dispatch directly, and our throttle
+			 * control algorithm is adaptive, and extra IO bytes
+			 * will be throttled for paying the debt
 			 */
-			tg_dispatch_in_debt(tg, bio, rw);
+			throtl_charge_bio(tg, bio);
 		} else {
 			/* if above limits, break to queue */
 			break;
-- 
2.39.5