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From: Bart Van Assche <bvanassche@acm.org>
To: Jens Axboe <axboe@kernel.dk>,
	Damien Le Moal <damien.lemoal@opensource.wdc.com>
Cc: linux-block@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
	Avri Altman <avri.altman@wdc.com>,
	Damien Le Moal <damien.lemoal@wdc.com>
Subject: Re: [PATCH 4/8] block/mq-deadline: Only use zone locking if necessary
Date: Mon, 9 Jan 2023 17:17:16 -0800	[thread overview]
Message-ID: <f47f32d8-92a3-b7d5-a462-d34da9263d34@acm.org> (raw)
In-Reply-To: <86eef990-0725-9669-6b7e-1fe935a6b648@kernel.dk>

On 1/9/23 17:03, Jens Axboe wrote:
> Because I'm really not thrilled to see the addition of various "is this
> device ordered" all over the place, and now we are getting "is this
> device ordered AND pipelined". Do you see what I mean? It's making
> things _worse_, not better, and we really should be making it better
> rather than pile more stuff on top of it.

Hi Jens,

I agree with you that the additional complexity is unfortunate.

For most zoned storage use cases a queue depth above one is not an 
option if the zoned device expects zoned write commands in LBA order. 
ATA controllers do not support preserving the command order. Transports 
like NVMeOF do not support preserving the command order either. UFS is 
an exception. The only use case supported by the UFS specification is a 
1:1 connection between UFS controller and UFS device with a link with a 
low BER between controller and device. UFS controllers must preserve the 
command order per command queue. I think this context is well suited for 
pipelining zoned write commands.

Thanks,

Bart.



  reply	other threads:[~2023-01-10  1:17 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-09 23:27 [PATCH 0/8] Enable zoned write pipelining for UFS devices Bart Van Assche
2023-01-09 23:27 ` [PATCH 1/8] block: Document blk_queue_zone_is_seq() and blk_rq_zone_is_seq() Bart Van Assche
2023-01-09 23:36   ` Damien Le Moal
2023-01-09 23:27 ` [PATCH 2/8] block: Introduce the blk_rq_is_seq_zone_write() function Bart Van Assche
2023-01-09 23:38   ` Damien Le Moal
2023-01-09 23:52     ` Bart Van Assche
2023-01-10  9:52       ` Niklas Cassel
2023-01-10 11:54         ` Damien Le Moal
2023-01-10 12:13           ` Niklas Cassel
2023-01-10 12:41             ` Damien Le Moal
2023-01-09 23:27 ` [PATCH 3/8] block: Introduce a request queue flag for pipelining zoned writes Bart Van Assche
2023-01-09 23:27 ` [PATCH 4/8] block/mq-deadline: Only use zone locking if necessary Bart Van Assche
2023-01-09 23:46   ` Damien Le Moal
2023-01-09 23:51     ` Bart Van Assche
2023-01-09 23:56       ` Damien Le Moal
2023-01-10  0:19         ` Bart Van Assche
2023-01-10  0:32           ` Damien Le Moal
2023-01-10  0:38             ` Jens Axboe
2023-01-10  0:41               ` Jens Axboe
2023-01-10  0:44                 ` Bart Van Assche
2023-01-10  0:48                   ` Jens Axboe
2023-01-10  0:56                     ` Bart Van Assche
2023-01-10  1:03                       ` Jens Axboe
2023-01-10  1:17                         ` Bart Van Assche [this message]
2023-01-10  1:48                           ` Jens Axboe
2023-01-10  2:24                     ` Damien Le Moal
2023-01-10  3:00                       ` Jens Axboe
2023-01-09 23:27 ` [PATCH 5/8] block/null_blk: Refactor null_queue_rq() Bart Van Assche
2023-01-09 23:27 ` [PATCH 6/8] block/null_blk: Add support for pipelining zoned writes Bart Van Assche
2023-01-09 23:27 ` [PATCH 7/8] scsi: Retry unaligned " Bart Van Assche
2023-01-09 23:51   ` Damien Le Moal
2023-01-09 23:55     ` Bart Van Assche
2023-01-09 23:27 ` [PATCH 8/8] scsi: ufs: Enable zoned write pipelining Bart Van Assche
2023-01-10  9:16   ` Avri Altman
2023-01-10 17:42     ` Bart Van Assche
2023-01-10 12:23   ` Bean Huo
2023-01-10 17:41     ` Bart Van Assche

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