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From: Jack Wang <jinpu.wang@ionos.com>
To: linux-raid@vger.kernel.org, song@kernel.org
Cc: Florian-Ewald Mueller <florian-ewald.mueller@ionos.com>,
	Yu Kuai <yukuai3@huawei.com>
Subject: [PATCH] md: add check for sleepers in md_wakeup_thread()
Date: Wed, 27 Mar 2024 12:40:22 +0100	[thread overview]
Message-ID: <20240327114022.74634-1-jinpu.wang@ionos.com> (raw)

From: Florian-Ewald Mueller <florian-ewald.mueller@ionos.com>

Check for sleeping thread before attempting its wake_up in
md_wakeup_thread() to avoid unnecessary spinlock contention.

With a 6.1 kernel, fio random read/write tests on many (>= 100)
virtual volumes, of 100 GiB each, on 3 md-raid5s on 8 SSDs each
(building a raid50), show by 3 to 4 % improved IOPS performance.

Signed-off-by: Florian-Ewald Mueller <florian-ewald.mueller@ionos.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
---
 drivers/md/md.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 7d7b982e369c..44253faa2633 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8083,7 +8083,8 @@ void md_wakeup_thread(struct md_thread __rcu *thread)
 	if (t) {
 		pr_debug("md: waking up MD thread %s.\n", t->tsk->comm);
 		set_bit(THREAD_WAKEUP, &t->flags);
-		wake_up(&t->wqueue);
+		if (wq_has_sleeper(&t->wqueue))
+			wake_up(&t->wqueue);
 	}
 	rcu_read_unlock();
 }
-- 
2.34.1


             reply	other threads:[~2024-03-27 11:40 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-27 11:40 Jack Wang [this message]
2024-04-10 21:36 ` [PATCH] md: add check for sleepers in md_wakeup_thread() Song Liu

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