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.
next prev 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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