linux-kernel - [PATCH AUTOSEL 5.15 29/29] Revert "block: reduce kblockd_mod_delayed_work

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Message-Id: <20211221015751.116328-29-sashal@kernel.org>
Date:   Mon, 20 Dec 2021 20:57:50 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jens Axboe <axboe@...nel.dk>, Alex Xu <alex_y_xu@...oo.ca>,
        kernel test robot <oliver.sang@...el.com>,
        Sasha Levin <sashal@...nel.org>, linux-block@...r.kernel.org
Subject: [PATCH AUTOSEL 5.15 29/29] Revert "block: reduce kblockd_mod_delayed_work_on() CPU consumption"

From: Jens Axboe <axboe@...nel.dk>

[ Upstream commit 87959fa16cfbcf76245c11559db1940069621274 ]

This reverts commit cb2ac2912a9ca7d3d26291c511939a41361d2d83.

Alex and the kernel test robot report that this causes a significant
performance regression with BFQ. I can reproduce that result, so let's
revert this one as we're close to -rc6 and we there's no point in trying
to rush a fix.

Link: https://lore.kernel.org/linux-block/1639853092.524jxfaem2.none@localhost/
Link: https://lore.kernel.org/lkml/20211219141852.GH14057@xsang-OptiPlex-9020/
Reported-by: Alex Xu (Hello71) <alex_y_xu@...oo.ca>
Reported-by: kernel test robot <oliver.sang@...el.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 block/blk-core.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index a728434fcff87..c2d912d0c976c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1625,8 +1625,6 @@ EXPORT_SYMBOL(kblockd_schedule_work);
 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork,
 				unsigned long delay)
 {
-	if (!delay)
-		return queue_work_on(cpu, kblockd_workqueue, &dwork->work);
 	return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
 }
 EXPORT_SYMBOL(kblockd_mod_delayed_work_on);
-- 
2.34.1