From: Jens Axboe <axboe@kernel.dk>
To: Ming Lei <ming.lei@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>,
Bart Van Assche <bvanassche@acm.org>,
virtualization@lists.linux-foundation.org,
linux-block@vger.kernel.org,
Stefan Hajnoczi <stefanha@redhat.com>,
Keith Busch <kbusch@kernel.org>
Subject: Re: [PATCH] blk-mq: avoid double ->queue_rq() because of early timeout
Date: Tue, 25 Oct 2022 12:11:39 -0600 [thread overview]
Message-ID: <bf375891-667f-1bcc-bd63-b90e757f5322@kernel.dk> (raw)
In-Reply-To: <20221025005501.281460-1-ming.lei@redhat.com>
On 10/24/22 6:55 PM, Ming Lei wrote:
> @@ -1593,10 +1598,18 @@ static void blk_mq_timeout_work(struct work_struct *work)
> if (!percpu_ref_tryget(&q->q_usage_counter))
> return;
>
> - blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &next);
> + /*
> + * Before walking tags, we must ensure any submit started before
> + * the current time has finished. Since the submit uses srcu or rcu,
> + * wait for a synchronization point to ensure all running submits
> + * have finished
> + */
> + blk_mq_wait_quiesce_done(q);
I'm a little worried about this bit - so we'll basically do a sync RCU
every time the timeout timer runs... Depending on machine load, that
can take a long time.
--
Jens Axboe
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next prev parent reply other threads:[~2022-10-25 18:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-25 0:55 [PATCH] blk-mq: avoid double ->queue_rq() because of early timeout Ming Lei
2022-10-25 14:04 ` Bart Van Assche
2022-10-25 18:11 ` Jens Axboe [this message]
2022-10-26 0:21 ` Ming Lei
2022-10-26 0:53 ` Jens Axboe
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