From: Christoph Hellwig <hch@lst.de>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Matthew Wilcox <willy@infradead.org>,
Luis Chamberlain <mcgrof@kernel.org>,
leon@kernel.org, hch@lst.de, kbusch@kernel.org, sagi@grimberg.me,
axboe@kernel.dk, joro@8bytes.org, brauner@kernel.org,
hare@suse.de, david@fromorbit.com, djwong@kernel.org,
john.g.garry@oracle.com, ritesh.list@gmail.com,
linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
linux-mm@kvack.org, gost.dev@samsung.com, p.raghav@samsung.com,
da.gomez@samsung.com, kernel@pankajraghav.com
Subject: Re: [RFC 2/4] blkdev: lift BLK_MAX_BLOCK_SIZE to page cache limit
Date: Thu, 20 Mar 2025 17:44:51 +0100 [thread overview]
Message-ID: <20250320164451.GA21364@lst.de> (raw)
In-Reply-To: <7cc6f537-aac4-4bfc-80f0-1829a850d56a@acm.org>
On Thu, Mar 20, 2025 at 09:34:50AM -0700, Bart Van Assche wrote:
> The fact that this change is proposed because there are device
> manufacturers that want to produce devices with block sizes larger than
> 64 KiB would be useful information for the commit message.
I think it's just the proposal that is very confused. Keith pointed
out that number of segments mostly matters when you have 4k
non-contiguous pages and that's where the quoted limit comes from.
The LBA size is a lower bound to the folio size in the page cache,
so the limit automatically increases with that, although in practice
the file system will usually allocate larger folios even with a smaller
block size, and I assume most systems (or at least the ones that care
about performance) actually use transparent huge pages/folios for
anonymous memory as well.
next prev parent reply other threads:[~2025-03-20 16:44 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-20 11:13 [RFC 0/4] nvme-pci: breaking the 512 KiB max IO boundary Luis Chamberlain
2025-03-20 11:13 ` [RFC 1/4] iomap: use BLK_MAX_BLOCK_SIZE for the iomap zero page Luis Chamberlain
2025-03-20 11:13 ` [RFC 2/4] blkdev: lift BLK_MAX_BLOCK_SIZE to page cache limit Luis Chamberlain
2025-03-20 16:01 ` Bart Van Assche
2025-03-20 16:06 ` Matthew Wilcox
2025-03-20 16:15 ` Bart Van Assche
2025-03-20 16:27 ` Matthew Wilcox
2025-03-20 16:34 ` Bart Van Assche
2025-03-20 16:44 ` Christoph Hellwig [this message]
2025-03-24 10:58 ` Bart Van Assche
2025-03-24 15:02 ` Matthew Wilcox
2025-03-20 11:13 ` [RFC 3/4] nvme-pci: bump segments to what the device can use Luis Chamberlain
2025-03-20 11:13 ` [RFC 4/4] nvme-pci: add quirk for qemu with bogus NOWS Luis Chamberlain
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