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Date: Thu, 20 Mar 2025 17:38:04 +0100
From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <kbusch@kernel.org>
Cc: Bart Van Assche <bvanassche@acm.org>, Christoph Hellwig <hch@lst.de>,
	Luis Chamberlain <mcgrof@kernel.org>, linux-fsdevel@vger.kernel.org,
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Subject: Re: [LSF/MM/BPF TOPIC] breaking the 512 KiB IO boundary on x86_64
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References: <Z9v-1xjl7dD7Tr-H@bombadil.infradead.org> <20250320141846.GA11512@lst.de> <a40a704f-22c8-4ae9-9800-301c9865cee4@acm.org> <Z9w7Nz-CxWSqj__H@kbusch-mbp.dhcp.thefacebook.com>
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On Thu, Mar 20, 2025 at 09:58:47AM -0600, Keith Busch wrote:
> I allocate out of hugetlbfs to reliably send direct IO at this size
> because the nvme driver's segment count is limited to 128.

It also works pretty well for buffered I/O for file systems supporting
larger folios.  I can trivially create 1MB folios in the page cache
on XFS and then do I/O on them.