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From: Jens Axboe <[email protected]>
To: Keith Busch <[email protected]>
Cc: [email protected], [email protected]
Subject: Re: [PATCH 1/4] block: add mq_ops->queue_rqs hook
Date: Mon, 20 Dec 2021 13:47:09 -0700	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 12/20/21 1:36 PM, Keith Busch wrote:
> On Wed, Dec 15, 2021 at 09:24:18AM -0700, Jens Axboe wrote:
>> +		/*
>> +		 * Peek first request and see if we have a ->queue_rqs() hook.
>> +		 * If we do, we can dispatch the whole plug list in one go. We
>> +		 * already know at this point that all requests belong to the
>> +		 * same queue, caller must ensure that's the case.
>> +		 *
>> +		 * Since we pass off the full list to the driver at this point,
>> +		 * we do not increment the active request count for the queue.
>> +		 * Bypass shared tags for now because of that.
>> +		 */
>> +		if (q->mq_ops->queue_rqs &&
>> +		    !(rq->mq_hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {
>> +			blk_mq_run_dispatch_ops(q,
>> +				q->mq_ops->queue_rqs(&plug->mq_list));
> 
> I think we still need to verify the queue isn't quiesced within
> blk_mq_run_dispatch_ops()'s rcu protected area, prior to calling
> .queue_rqs(). Something like below. Or is this supposed to be the
> low-level drivers responsibility now?

Yes, that seems very reasonable, and I'd much rather do that than punt it
to the driver. Care to send it as a real patch?

-- 
Jens Axboe


  reply	other threads:[~2021-12-20 20:47 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-15 16:24 [PATCHSET v3 0/4] Add support for list issue Jens Axboe
2021-12-15 16:24 ` [PATCH 1/4] block: add mq_ops->queue_rqs hook Jens Axboe
2021-12-16  9:01   ` Christoph Hellwig
2021-12-20 20:36   ` Keith Busch
2021-12-20 20:47     ` Jens Axboe [this message]
2021-12-15 16:24 ` [PATCH 2/4] nvme: split command copy into a helper Jens Axboe
2021-12-16  9:01   ` Christoph Hellwig
2021-12-16 12:17   ` Max Gurtovoy
2021-12-15 16:24 ` [PATCH 3/4] nvme: separate command prep and issue Jens Axboe
2021-12-16  9:02   ` Christoph Hellwig
2021-12-15 16:24 ` [PATCH 4/4] nvme: add support for mq_ops->queue_rqs() Jens Axboe
2021-12-15 17:29   ` Keith Busch
2021-12-15 20:27     ` Jens Axboe
2021-12-16  9:08   ` Christoph Hellwig
2021-12-16 13:06     ` Max Gurtovoy
2021-12-16 15:48       ` Jens Axboe
2021-12-16 16:00         ` Max Gurtovoy
2021-12-16 16:05           ` Jens Axboe
2021-12-16 16:19             ` Max Gurtovoy
2021-12-16 16:25               ` Jens Axboe
2021-12-16 16:34                 ` Max Gurtovoy
2021-12-16 16:36                   ` Jens Axboe
2021-12-16 16:57                     ` Max Gurtovoy
2021-12-16 17:16                       ` Jens Axboe
2021-12-19 12:14                         ` Max Gurtovoy
2021-12-19 14:48                           ` Jens Axboe
2021-12-20 10:11                             ` Max Gurtovoy
2021-12-20 14:19                               ` Jens Axboe
2021-12-20 14:25                                 ` Jens Axboe
2021-12-20 15:29                                 ` Max Gurtovoy
2021-12-20 16:34                                   ` Jens Axboe
2021-12-20 18:48                                     ` Max Gurtovoy
2021-12-20 18:58                                       ` Jens Axboe
2021-12-21 10:20                                         ` Max Gurtovoy
2021-12-21 15:23                                           ` Jens Axboe
2021-12-21 15:29                                             ` Max Gurtovoy
2021-12-21 15:33                                               ` Jens Axboe
2021-12-21 16:08                                                 ` Max Gurtovoy
2021-12-16 15:45     ` Jens Axboe
2021-12-16 16:15       ` Christoph Hellwig
2021-12-16 16:27         ` Jens Axboe
2021-12-16 16:30           ` Christoph Hellwig
2021-12-16 16:36             ` Jens Axboe
2021-12-16 13:02   ` Max Gurtovoy
2021-12-16 15:59     ` Jens Axboe
2021-12-16 16:06       ` Max Gurtovoy
2021-12-16 16:09         ` Jens Axboe
  -- strict thread matches above, loose matches on Subject: below --
2021-12-16 16:05 [PATCHSET v4 0/4] Add support for list issue Jens Axboe
2021-12-16 16:05 ` [PATCH 1/4] block: add mq_ops->queue_rqs hook Jens Axboe
2021-12-16 16:38 [PATCHSET v5 0/4] Add support for list issue Jens Axboe
2021-12-16 16:38 ` [PATCH 1/4] block: add mq_ops->queue_rqs hook Jens Axboe

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