From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: John Garry <john.g.garry@oracle.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>, <axboe@kernel.dk>,
<agk@redhat.com>, <snitzer@kernel.org>, <song@kernel.org>,
<yukuai3@huawei.com>, <hch@lst.de>, <nilay@linux.ibm.com>,
<dm-devel@lists.linux.dev>, <linux-kernel@vger.kernel.org>,
<linux-raid@vger.kernel.org>, <linux-block@vger.kernel.org>,
<ojaswin@linux.ibm.com>, <martin.petersen@oracle.com>
Subject: Re: [PATCH v3 5/5] block: use chunk_sectors when evaluating stacked atomic write limits
Date: Tue, 08 Jul 2025 21:39:11 -0400 [thread overview]
Message-ID: <yq1a55edu8i.fsf@ca-mkp.ca.oracle.com> (raw)
In-Reply-To: <803d0903-2382-4219-b81e-9d676bd5de1f@oracle.com> (John Garry's message of "Thu, 3 Jul 2025 17:01:00 +0100")
John,
> For io_min/opt, maybe reduce to a factor of the stripe size / width
> (and which fits in a unsigned int).
>
> I am not sure if it is even sane to have such huge values in io_min
> and the bottom disk io_min should be used directly instead.
The intent for io_min was to convey the physical_block_size in the case
of an individual drive. And for it to be set to the stripe chunk size in
stacking scenarios that would otherwise involve read-modify-write (i.e.
RAID5 and RAID6).
io_opt was meant to communicate the stripe width. Reporting very large
values for io_opt is generally counterproductive since we can't write
multiple gigabytes in a single operation anyway.
logical <= physical <= io_min <= io_opt <= max_sectors <= max_hw_sectors
--
Martin K. Petersen
next prev parent reply other threads:[~2025-07-09 1:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-03 11:46 [PATCH v3 0/5] block/md/dm: set chunk_sectors from stacked dev stripe size John Garry
2025-07-03 11:46 ` [PATCH v3 1/5] block: sanitize chunk_sectors for atomic write limits John Garry
2025-07-03 11:46 ` [PATCH v3 2/5] md/raid0: set chunk_sectors limit John Garry
2025-07-03 11:46 ` [PATCH v3 3/5] md/raid10: " John Garry
2025-07-03 11:46 ` [PATCH v3 4/5] dm-stripe: limit chunk_sectors to the stripe size John Garry
2025-07-03 11:46 ` [PATCH v3 5/5] block: use chunk_sectors when evaluating stacked atomic write limits John Garry
2025-07-03 13:31 ` Mikulas Patocka
2025-07-03 14:17 ` John Garry
2025-07-03 15:36 ` Mikulas Patocka
2025-07-03 16:01 ` John Garry
2025-07-09 1:39 ` Martin K. Petersen [this message]
2025-07-09 13:16 ` John Garry
2025-07-21 14:09 ` John Garry
2025-07-22 3:43 ` Martin K. Petersen
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