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From: Jonathan Corbet <corbet@lwn.net>
To: Milosz Tanski <milosz@adfin.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	linux-aio@kvack.org, Mel Gorman <mgorman@suse.de>,
	Volker Lendecke <Volker.Lendecke@sernet.de>,
	Tejun Heo <tj@kernel.org>, Jeff Moyer <jmoyer@redhat.com>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [RFC v2 0/5] Non-blockling buffered fs read (page cache only)
Date: Mon, 22 Sep 2014 10:12:21 -0400	[thread overview]
Message-ID: <20140922101221.4bf46809@lwn.net> (raw)
In-Reply-To: <CANP1eJEhHyA93kDUCz_=0vDjdPXz7g0x1SmW+q060fntQAbrYA@mail.gmail.com>

On Fri, 19 Sep 2014 13:33:14 -0400
Milosz Tanski <milosz@adfin.com> wrote:

> >  - Non-blocking I/O has long been supported with a well-understood set
> >    of operations - O_NONBLOCK and fcntl().  Why do we need a different
> >    mechanism here - one that's only understood in the context of
> >    buffered file I/O?  I assume you didn't want to implement support
> >    for poll() and all that, but is that a good enough reason to add a
> >    new Linux-specific non-blocking I/O technique?  
> 
> I realized that I didn't answer this question well in my other long
> email. O_NONBLOCK doesn't work on files under any commonly used OS,
> and people have gotten use to this behavior so I doubt we could change
> that without breaking a lot of folks applications.

So I'm not contesting this, but I am genuinely curious: do you think
there are applications out there requesting non-blocking behavior on
regular files that will then break if they actually get non-blocking
behavior?  I don't suppose you have an example?

Thanks,

jon

  reply	other threads:[~2014-09-22 14:12 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-15 20:20 [RFC PATCH 0/7] Non-blockling buffered fs read (page cache only) Milosz Tanski
2014-09-15 20:20 ` [PATCH 1/7] Prepare for adding a new readv/writev with user flags Milosz Tanski
2014-09-15 20:28   ` Al Viro
2014-09-15 21:15     ` Christoph Hellwig
2014-09-15 21:44       ` Milosz Tanski
2014-09-15 20:20 ` [PATCH 2/7] Define new syscalls readv2,preadv2,writev2,pwritev2 Milosz Tanski
2014-09-16 19:20   ` Jeff Moyer
2014-09-16 19:54     ` Milosz Tanski
2014-09-16 21:03     ` Christoph Hellwig
2014-09-17 15:43   ` Theodore Ts'o
2014-09-17 16:05     ` Milosz Tanski
2014-09-17 16:59       ` Theodore Ts'o
2014-09-17 17:24         ` Zach Brown
2014-09-15 20:20 ` [PATCH 3/7] Export new vector IO (with flags) to userland Milosz Tanski
2014-09-15 20:21 ` [PATCH 4/7] O_NONBLOCK flag for readv2/preadv2 Milosz Tanski
2014-09-16 19:19   ` Jeff Moyer
2014-09-16 19:44     ` Milosz Tanski
2014-09-16 19:53       ` Jeff Moyer
2014-09-15 20:21 ` [PATCH 5/7] documentation updates Christoph Hellwig
2014-09-15 20:21 ` [PATCH 6/7] move flags enforcement to vfs_preadv/vfs_pwritev Christoph Hellwig
2014-09-15 21:15   ` Christoph Hellwig
2014-09-15 21:45     ` Milosz Tanski
2014-09-15 20:22 ` [PATCH 7/7] check for O_NONBLOCK in all read_iter instances Christoph Hellwig
2014-09-16 19:27   ` Jeff Moyer
2014-09-16 19:45     ` Milosz Tanski
2014-09-16 21:42       ` Dave Chinner
2014-09-17 12:24         ` Benjamin LaHaise
2014-09-17 13:47           ` Theodore Ts'o
2014-09-17 13:56             ` Benjamin LaHaise
2014-09-17 15:33               ` Milosz Tanski
2014-09-17 15:49                 ` Theodore Ts'o
2014-09-17 15:52               ` Zach Brown
2014-09-16 21:04     ` Christoph Hellwig
2014-09-16 21:24       ` Jeff Moyer
2014-09-15 20:27 ` [RFC PATCH 0/7] Non-blockling buffered fs read (page cache only) Milosz Tanski
2014-09-15 21:33 ` Andreas Dilger
2014-09-15 22:13   ` Milosz Tanski
2014-09-15 22:36   ` Elliott, Robert (Server Storage)
2014-09-16 18:24     ` Zach Brown
2014-09-19 11:21     ` Christoph Hellwig
2014-09-22 15:48       ` Jeff Moyer
2014-09-22 16:32         ` Milosz Tanski
2014-09-22 16:42           ` Christoph Hellwig
2014-09-22 17:02             ` Milosz Tanski
2014-09-22 16:25       ` Elliott, Robert (Server Storage)
2014-09-15 21:58 ` Jeff Moyer
2014-09-15 22:27   ` Milosz Tanski
2014-09-16 13:44     ` Jeff Moyer
2014-09-19 11:23   ` Christoph Hellwig
2014-09-16 19:30 ` Jeff Moyer
2014-09-16 20:34   ` Milosz Tanski
2014-09-16 20:49     ` Jeff Moyer
2014-09-17 14:49 ` [RFC 1/2] aio: async readahead Benjamin LaHaise
2014-09-17 15:26   ` [RFC 2/2] ext4: async readpage for indirect style inodes Benjamin LaHaise
2014-09-19 11:26   ` [RFC 1/2] aio: async readahead Christoph Hellwig
2014-09-19 16:01     ` Benjamin LaHaise
2014-09-17 22:20 ` [RFC v2 0/5] Non-blockling buffered fs read (page cache only) Milosz Tanski
2014-09-17 22:20   ` [RFC v2 1/5] Prepare for adding a new readv/writev with user flags Milosz Tanski
2014-09-17 22:20   ` [RFC v2 2/5] Define new syscalls readv2,preadv2,writev2,pwritev2 Milosz Tanski
2014-09-18 18:48     ` Darrick J. Wong
2014-09-19 10:52       ` Christoph Hellwig
2014-09-20  0:19         ` Darrick J. Wong
2014-09-17 22:20   ` [RFC v2 3/5] Export new vector IO (with flags) to userland Milosz Tanski
2014-09-17 22:20   ` [RFC v2 4/5] O_NONBLOCK flag for readv2/preadv2 Milosz Tanski
2014-09-19 11:27     ` Christoph Hellwig
2014-09-19 11:59       ` Milosz Tanski
2014-09-22 17:12     ` Jeff Moyer
2014-09-17 22:20   ` [RFC v2 5/5] Check for O_NONBLOCK in all read_iter instances Milosz Tanski
2014-09-19 11:26     ` Christoph Hellwig
2014-09-19 14:42   ` [RFC v2 0/5] Non-blockling buffered fs read (page cache only) Jonathan Corbet
2014-09-19 16:13     ` Volker Lendecke
2014-09-19 17:19     ` Milosz Tanski
2014-09-19 17:33     ` Milosz Tanski
2014-09-22 14:12       ` Jonathan Corbet [this message]
2014-09-22 14:24         ` Jeff Moyer
2014-09-22 14:25         ` Christoph Hellwig
2014-09-22 14:30         ` Milosz Tanski
2014-09-24 21:46 ` [RFC v3 0/4] vfs: " Milosz Tanski
2014-09-24 21:46   ` [RFC v3 1/4] vfs: Prepare for adding a new preadv/pwritev with user flags Milosz Tanski
2014-09-24 21:46   ` [RFC v3 2/4] vfs: Define new syscalls preadv2,pwritev2 Milosz Tanski
2014-09-24 21:46   ` [RFC v3 3/4] vfs: Export new vector IO syscalls (with flags) to userland Milosz Tanski
2014-09-24 21:46   ` [RFC v3 4/4] vfs: RWF_NONBLOCK flag for preadv2 Milosz Tanski
2014-09-25  4:06   ` [RFC v3 0/4] vfs: Non-blockling buffered fs read (page cache only) Michael Kerrisk
2014-09-25 11:16     ` Jan Kara
2014-09-25 15:48     ` Milosz Tanski
2014-10-08  2:53   ` Milosz Tanski

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