From: Christoph Hellwig <hch@infradead.org>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>,
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: Wed, 5 Feb 2025 08:00:40 -0800 [thread overview]
Message-ID: <Z6OLKInjfd1QxXRI@infradead.org> (raw)
In-Reply-To: <yq1ikppdsv3.fsf@ca-mkp.ca.oracle.com>
On Tue, Feb 04, 2025 at 09:36:46PM -0500, Martin K. Petersen wrote:
>
> Christoph,
>
> >> 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.
> >
> > Hmm, optimal == max is odd,
>
> What they mean to convey is that "device has no constraints". As opposed
> to a value of 0 which means "not reported".
I'm pretty sure that confuses some users, given normally optimal == lba
size mean not reported. Either way we really need to document these
somewhere.
next prev parent reply other threads:[~2025-02-05 16:00 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
2025-02-04 13:50 ` Christoph Hellwig
2025-02-05 2:36 ` Martin K. Petersen
2025-02-05 16:00 ` Christoph Hellwig [this message]
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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