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From: Christoph Hellwig <hch@lst.de>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
	Jan Kara <jack@suse.cz>
Subject: Re: [PATCH 0/2] Submit split bios in LBA order
Date: Thu, 23 Mar 2023 09:27:56 +0100	[thread overview]
Message-ID: <20230323082756.GD21977@lst.de> (raw)
In-Reply-To: <da0c7538-1a51-61dd-6359-8c618fde6c1b@acm.org>

On Mon, Mar 20, 2023 at 10:22:41AM -0700, Bart Van Assche wrote:
> How to achieve optimal performance with REQ_OP_ZONE_APPEND for SCSI 
> devices? My understanding of how REQ_OP_ZONE_APPEND works for SCSI devices 
> is as follows:
> * ATA devices cannot support this operation directly because there are
>   not enough bits in the ATA sense data to report where appended data
>   has been written.

ATA doesn't really have autosense in the SCSI way.  It could be handled
the same way that CDL completions are handled.  That is a complete
mess, and between CDL and Zone Append we'll probably eventually need
an extended FIS for SATA if we want to keep ATA alive.

> * T10 has not yet started with standardizing a zone append operation.

Time to get it started then!

> * The code that emulates REQ_OP_ZONE_APPEND for SCSI devices (in
>   sd_zbc.c) serializes REQ_OP_ZONE_APPEND operations (QD=1).

Because that's the only thing that actually works.

> * To achieve optimal performance, QD > 1 is required.

If you have something magic that works, this code is the place to take
advantage of it.

  parent reply	other threads:[~2023-03-23  8:28 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-17 19:59 [PATCH 0/2] Submit split bios in LBA order Bart Van Assche
2023-03-17 19:59 ` [PATCH 1/2] block: Split blk_recalc_rq_segments() Bart Van Assche
2023-03-18  6:38   ` Christoph Hellwig
2023-03-17 19:59 ` [PATCH 2/2] block: Split and submit bios in LBA order Bart Van Assche
2023-03-17 22:28   ` Jan Kara
2023-03-18  6:33     ` Christoph Hellwig
2023-03-17 23:38   ` Ming Lei
2023-03-17 23:45     ` Bart Van Assche
2023-03-20 23:28       ` Ming Lei
2023-03-20 23:32         ` Bart Van Assche
2023-03-21  0:44           ` Ming Lei
2023-03-21  1:46             ` Damien Le Moal
2023-03-21  2:17               ` Ming Lei
2023-03-21  3:24                 ` Damien Le Moal
2023-03-21  8:00                   ` Ming Lei
2023-03-21  8:51                     ` Damien Le Moal
2023-03-21  9:09                       ` Christoph Hellwig
2023-03-21  9:50                         ` Damien Le Moal
2023-03-21  5:55           ` Christoph Hellwig
2023-03-21 14:36             ` Bart Van Assche
2023-03-23  8:26               ` Christoph Hellwig
2023-03-23 10:28                 ` Damien Le Moal
2023-03-23 16:27                   ` Bart Van Assche
2023-03-23 22:53                     ` Damien Le Moal
2023-03-24 16:55                       ` Bart Van Assche
2023-03-25  2:00                         ` Damien Le Moal
2023-03-25 16:31                           ` Bart Van Assche
2023-03-26  1:45                             ` Damien Le Moal
2023-03-26 23:45                               ` Christoph Hellwig
2023-03-27 21:06                                 ` Bart Van Assche
2023-03-27 23:43                                   ` Christoph Hellwig
2023-04-06 20:30                                     ` Bart Van Assche
2023-03-27 21:20                               ` Bart Van Assche
2023-03-18  6:42   ` Christoph Hellwig
2023-03-18  6:29 ` [PATCH 0/2] Submit split " Christoph Hellwig
2023-03-20 17:22   ` Bart Van Assche
2023-03-20 21:06     ` Khazhy Kumykov
2023-03-23  8:27     ` Christoph Hellwig [this message]
2023-03-24 17:05       ` Bart Van Assche
2023-03-25  2:15         ` Damien Le Moal
2023-03-26 23:42           ` Christoph Hellwig
2023-03-26 23:44         ` Christoph Hellwig
2023-04-06 20:32           ` Bart Van Assche

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