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From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
	Mikulas Patocka <mpatocka@redhat.com>,
	Jens Axboe <axboe@kernel.dk>, Alasdair Kergon <agk@redhat.com>,
	Mike Snitzer <snitzer@kernel.org>,
	Zdenek Kabelac <zkabelac@redhat.com>,
	Milan Broz <gmazyland@gmail.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, 04 Feb 2025 08:02:17 -0500	[thread overview]
Message-ID: <yq1zfj1eusl.fsf@ca-mkp.ca.oracle.com> (raw)
In-Reply-To: <Z6GsWU9tt6dYfqBL@infradead.org> (Christoph Hellwig's message of "Mon, 3 Feb 2025 21:57:45 -0800")


Christoph,

> 0xffff as the max and a weirdly uneven number even for partity RAID
> seems like a good value to ignore by default.

Quite a few SCSI devices report 0xffff to indicate that the optimal
transfer length is the same as the maximum transfer length which for
low-byte commands is capped at 0xffff. That's where the odd value comes
from in some cases.

> But then again just dealing with USB will probably catch the majority
> of cases.

Yep.

-- 
Martin K. Petersen	Oracle Linux Engineering

  reply	other threads:[~2025-02-04 13:02 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
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 [this message]
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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