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From: David Howells <dhowells@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: dhowells@redhat.com, Jens Axboe <axboe@kernel.dk>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Matthew Wilcox <willy@infradead.org>, Jan Kara <jack@suse.cz>,
	Jeff Layton <jlayton@kernel.org>,
	David Hildenbrand <david@redhat.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	Hillf Danton <hdanton@sina.com>,
	linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	syzbot+a440341a59e3b7142895@syzkaller.appspotmail.com,
	Christoph Hellwig <hch@lst.de>,
	John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH v12 01/10] vfs, iomap: Fix generic_file_splice_read() to avoid reversion of ITER_PIPE
Date: Thu, 09 Feb 2023 10:50:30 +0000	[thread overview]
Message-ID: <531132.1675939830@warthog.procyon.org.uk> (raw)
In-Reply-To: <Y+PLrOM05FMCiTIg@infradead.org>

Christoph Hellwig <hch@infradead.org> wrote:

> I defintively like the idea of killing ITER_PIPE.  Isn't the 16
> folios in a folio tree often much less than what we could fit into
> a single pipe buf?  Unless you have a file system that can use
> huge folios for buffered I/O and actually does this might significantly
> limit performance.

There's a loop there that repeats the filemap_get_pages() until either the
pipe is full or we hit EOF, the same as in filemap_read() (upon which this is
based).

I want to use filemap_get_pages() if I can as that does all the readahead
stuff.  What might be nice, though, is if I could tell it to return rather
than waiting for a folio to come uptodate if it has already returned a folio
so that I can push the other side of the splice along whilst the read is in
progress.

David



  parent reply	other threads:[~2023-02-09 10:50 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-07 17:12 [PATCH v12 00/10] iov_iter: Improve page extraction (pin or just list) David Howells
2023-02-07 17:12 ` [PATCH v12 01/10] vfs, iomap: Fix generic_file_splice_read() to avoid reversion of ITER_PIPE David Howells
2023-02-08  5:26   ` Christoph Hellwig
2023-02-08 16:09   ` David Howells
2023-02-08 16:19     ` Christoph Hellwig
2023-02-08 17:21     ` Matthew Wilcox
2023-02-08 18:15     ` David Howells
2023-02-09 10:50     ` David Howells [this message]
2023-02-07 17:12 ` [PATCH v12 02/10] iov_iter: Kill ITER_PIPE David Howells
2023-02-07 17:12 ` [PATCH v12 03/10] iov_iter: Define flags to qualify page extraction David Howells
2023-02-07 17:12 ` [PATCH v12 04/10] iov_iter: Add a function to extract a page list from an iterator David Howells
2023-02-07 17:13 ` [PATCH v12 05/10] iomap: Don't get an reference on ZERO_PAGE for direct I/O block zeroing David Howells
2023-02-07 17:13 ` [PATCH v12 06/10] block: Fix bio_flagged() so that gcc can better optimise it David Howells
2023-02-07 17:13 ` [PATCH v12 07/10] block: Replace BIO_NO_PAGE_REF with BIO_PAGE_REFFED with inverted logic David Howells
2023-02-07 17:13 ` [PATCH v12 08/10] block: Add BIO_PAGE_PINNED and associated infrastructure David Howells
2023-02-07 17:13 ` [PATCH v12 09/10] block: Convert bio_iov_iter_get_pages to use iov_iter_extract_pages David Howells
2023-02-07 17:13 ` [PATCH v12 10/10] block: convert bio_map_user_iov " David Howells
2023-02-07 18:49 ` [PATCH v12 00/10] iov_iter: Improve page extraction (pin or just list) Jens Axboe
2023-02-07 18:51 ` David Howells

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