From: Christoph Hellwig <hch@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
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: Wed, 8 Feb 2023 08:19:56 -0800 [thread overview]
Message-ID: <Y+PLrOM05FMCiTIg@infradead.org> (raw)
In-Reply-To: <176199.1675872591@warthog.procyon.org.uk>
On Wed, Feb 08, 2023 at 04:09:51PM +0000, David Howells wrote:
> How about one of two different solutions?
>
> (1) Repurpose the function I proposed for generic_file_splice_read() but only
> for splicing from O_DIRECT files; reading from non-O_DIRECT files would
> use an ITER_PIPE as upstream.
Given the amounts of problems we had with O_DIRECT vs splice, and the
fact that even doing this is a bit pointless that seems sensible to me.
> for splicing from O_DIRECT files, as (1), but also replace the splice
> from a buffered file with something like the patch below. This uses
> filemap_get_pages() to do the reading and to get a bunch of folios from
> the pagecache that we can then splice into the pipe directly.
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.
With that in mind I'll try to find some time to review your actual
patch, but I'm a little busy at the moment.
next prev parent reply other threads:[~2023-02-08 16:20 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 [this message]
2023-02-08 17:21 ` Matthew Wilcox
2023-02-08 18:15 ` David Howells
2023-02-09 10:50 ` David Howells
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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