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From: Christoph Hellwig <hch@infradead.org>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>, Alasdair Kergon <agk@redhat.com>,
	Mike Snitzer <snitzer@kernel.org>,
	Zdenek Kabelac <zkabelac@redhat.com>,
	linux-block@vger.kernel.org, dm-devel@lists.linux.dev
Subject: Re: [PATCH] blk-settings: round down io_opt to at least 4K
Date: Tue, 21 Jan 2025 22:12:13 -0800	[thread overview]
Message-ID: <Z5CMPdUFNj0SvzpE@infradead.org> (raw)
In-Reply-To: <81b399f6-55f5-4aa2-0f31-8b4f8a44e6a4@redhat.com>

On Mon, Jan 20, 2025 at 04:16:26PM +0100, Mikulas Patocka wrote:
> Some SATA SSDs and most NVMe SSDs report physical block size 512 bytes,
> but they use 4K remapping table internally and they do slow
> read-modify-write cycle for requests that are not aligned on 4K boundary.
> Therefore, io_opt should be aligned on 4K.

Not really.  I mean it's always smart to not do tiny unaligned I/O
unless you have to.  So we're not just going to cap an exported value
to a magic number because of something.


> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
> Fixes: a23634644afc ("block: take io_opt and io_min into account for max_sectors")
> Fixes: 9c0ba14828d6 ("blk-settings: round down io_opt to physical_block_size")

Please explain how this actually is a fix.


  reply	other threads:[~2025-01-22  6:12 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-01-20 15:16 [PATCH] blk-settings: round down io_opt to at least 4K Mikulas Patocka
2025-01-22  6:12 ` Christoph Hellwig [this message]
2025-02-03 13:38   ` Mikulas Patocka
2025-02-03 19:02     ` Martin K. Petersen
2025-02-03 21:05       ` Mikulas Patocka
2025-02-04  3:30         ` Martin K. Petersen
2025-02-04  5:57           ` Christoph Hellwig
2025-02-04 13:02             ` Martin K. Petersen
2025-02-04 13:50               ` Christoph Hellwig
2025-02-05  2:36                 ` Martin K. Petersen
2025-02-05 16:00                   ` Christoph Hellwig
2025-02-04 14:56           ` Mikulas Patocka
2025-02-05  2:41             ` Martin K. Petersen
2025-02-10 12:54               ` Mikulas Patocka
2025-02-10 17:02                 ` Milan Broz
2025-02-04  5:56         ` Christoph Hellwig
2025-02-04  5:55     ` Christoph Hellwig
2025-01-23 12:24 ` Milan Broz

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