From: Christoph Hellwig <hch@infradead.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org
Subject: Re: [PATCH 3/8] blk-mq: add mq_ops->commit_rqs()
Date: Tue, 27 Nov 2018 23:16:01 -0800 [thread overview]
Message-ID: <20181128071601.GA11774@infradead.org> (raw)
In-Reply-To: <20181126163556.5181-4-axboe@kernel.dk>
On Mon, Nov 26, 2018 at 09:35:51AM -0700, Jens Axboe wrote:
> blk-mq passes information to the hardware about any given request being
> the last that we will issue in this sequence. The point is that hardware
> can defer costly doorbell type writes to the last request. But if we run
> into errors issuing a sequence of requests, we may never send the request
> with bd->last == true set. For that case, we need a hook that tells the
> hardware that nothing else is coming right now.
>
> For failures returned by the drivers ->queue_rq() hook, the driver is
> responsible for flushing pending requests, if it uses bd->last to
> optimize that part. This works like before, no changes there.
>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
This looks fine, but normally I would only add the method together with
the actual user..
Reviewed-by: Christoph Hellwig <hch@lst.de>
WARNING: multiple messages have this Message-ID (diff)
From: hch@infradead.org (Christoph Hellwig)
Subject: [PATCH 3/8] blk-mq: add mq_ops->commit_rqs()
Date: Tue, 27 Nov 2018 23:16:01 -0800 [thread overview]
Message-ID: <20181128071601.GA11774@infradead.org> (raw)
In-Reply-To: <20181126163556.5181-4-axboe@kernel.dk>
On Mon, Nov 26, 2018@09:35:51AM -0700, Jens Axboe wrote:
> blk-mq passes information to the hardware about any given request being
> the last that we will issue in this sequence. The point is that hardware
> can defer costly doorbell type writes to the last request. But if we run
> into errors issuing a sequence of requests, we may never send the request
> with bd->last == true set. For that case, we need a hook that tells the
> hardware that nothing else is coming right now.
>
> For failures returned by the drivers ->queue_rq() hook, the driver is
> responsible for flushing pending requests, if it uses bd->last to
> optimize that part. This works like before, no changes there.
>
> Signed-off-by: Jens Axboe <axboe at kernel.dk>
This looks fine, but normally I would only add the method together with
the actual user..
Reviewed-by: Christoph Hellwig <hch at lst.de>
next prev parent reply other threads:[~2018-11-28 7:16 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-26 16:35 [PATCHSET 0/8] block plugging improvements Jens Axboe
2018-11-26 16:35 ` Jens Axboe
2018-11-26 16:35 ` [PATCH 1/8] block: sum requests in the plug structure Jens Axboe
2018-11-26 16:35 ` Jens Axboe
2018-11-26 17:02 ` Christoph Hellwig
2018-11-26 17:02 ` Christoph Hellwig
2018-11-26 16:35 ` [PATCH 2/8] block: improve logic around when to sort a plug list Jens Axboe
2018-11-26 16:35 ` Jens Axboe
2018-11-27 23:31 ` Omar Sandoval
2018-11-27 23:31 ` Omar Sandoval
2018-11-27 23:49 ` Jens Axboe
2018-11-27 23:49 ` Jens Axboe
2018-11-27 23:55 ` Omar Sandoval
2018-11-27 23:55 ` Omar Sandoval
2018-11-27 23:59 ` Jens Axboe
2018-11-27 23:59 ` Jens Axboe
2018-11-28 0:05 ` Omar Sandoval
2018-11-28 0:05 ` Omar Sandoval
2018-11-28 0:16 ` Jens Axboe
2018-11-28 0:16 ` Jens Axboe
2018-11-26 16:35 ` [PATCH 3/8] blk-mq: add mq_ops->commit_rqs() Jens Axboe
2018-11-26 16:35 ` Jens Axboe
2018-11-27 23:43 ` Omar Sandoval
2018-11-27 23:43 ` Omar Sandoval
2018-11-28 1:38 ` Ming Lei
2018-11-28 1:38 ` Ming Lei
2018-11-28 7:16 ` Christoph Hellwig [this message]
2018-11-28 7:16 ` Christoph Hellwig
2018-11-28 12:54 ` Jens Axboe
2018-11-28 12:54 ` Jens Axboe
2018-11-26 16:35 ` [PATCH 4/8] nvme: implement mq_ops->commit_rqs() hook Jens Axboe
2018-11-26 16:35 ` Jens Axboe
2018-11-28 7:20 ` Christoph Hellwig
2018-11-28 7:20 ` Christoph Hellwig
2018-11-28 13:07 ` Jens Axboe
2018-11-28 13:07 ` Jens Axboe
2018-11-26 16:35 ` [PATCH 5/8] virtio_blk: " Jens Axboe
2018-11-26 16:35 ` Jens Axboe
2018-11-27 23:45 ` Omar Sandoval
2018-11-27 23:45 ` Omar Sandoval
2018-11-28 3:05 ` Michael S. Tsirkin
2018-11-28 3:05 ` Michael S. Tsirkin
2018-11-28 2:10 ` Ming Lei
2018-11-28 2:10 ` Ming Lei
2018-11-28 2:34 ` Jens Axboe
2018-11-28 2:34 ` Jens Axboe
2018-11-29 1:23 ` Ming Lei
2018-11-29 1:23 ` Ming Lei
2018-11-29 2:19 ` Jens Axboe
2018-11-29 2:19 ` Jens Axboe
2018-11-29 2:51 ` Ming Lei
2018-11-29 2:51 ` Ming Lei
2018-11-29 3:13 ` Jens Axboe
2018-11-29 3:13 ` Jens Axboe
2018-11-29 3:27 ` Ming Lei
2018-11-29 3:27 ` Ming Lei
2018-11-29 3:53 ` Jens Axboe
2018-11-29 3:53 ` Jens Axboe
2018-11-28 7:21 ` Christoph Hellwig
2018-11-28 7:21 ` Christoph Hellwig
2018-11-26 16:35 ` [PATCH 6/8] ataflop: " Jens Axboe
2018-11-26 16:35 ` Jens Axboe
2018-11-27 23:46 ` Omar Sandoval
2018-11-27 23:46 ` Omar Sandoval
2018-11-28 7:22 ` Christoph Hellwig
2018-11-28 7:22 ` Christoph Hellwig
2018-11-28 13:09 ` Jens Axboe
2018-11-28 13:09 ` Jens Axboe
2018-11-26 16:35 ` [PATCH 7/8] blk-mq: use bd->last == true for list inserts Jens Axboe
2018-11-26 16:35 ` Jens Axboe
2018-11-27 23:49 ` Omar Sandoval
2018-11-27 23:49 ` Omar Sandoval
2018-11-27 23:51 ` Jens Axboe
2018-11-27 23:51 ` Jens Axboe
2018-11-28 1:49 ` Ming Lei
2018-11-28 1:49 ` Ming Lei
2018-11-28 2:37 ` Jens Axboe
2018-11-28 2:37 ` Jens Axboe
2018-11-26 16:35 ` [PATCH 8/8] blk-mq: add plug case for devices that implement ->commits_rqs() Jens Axboe
2018-11-26 16:35 ` Jens Axboe
2018-11-28 7:26 ` Christoph Hellwig
2018-11-28 7:26 ` Christoph Hellwig
2018-11-28 13:11 ` Jens Axboe
2018-11-28 13:11 ` Jens Axboe
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