From: Anthony Liguori <anthony@codemonkey.ws>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
qemu-devel@nongnu.org, kvm-devel <kvm@vger.kernel.org>
Subject: Re: [Qemu-devel] [RFC] Replace posix-aio with custom thread pool
Date: Wed, 10 Dec 2008 12:50:17 -0600 [thread overview]
Message-ID: <49400F69.8080707@codemonkey.ws> (raw)
In-Reply-To: <493FFC8E.9080802@redhat.com>
Gerd Hoffmann wrote:
>>> To solve this in userland without kernel aio we'd need to open (not
>>> just dup)
>>>
>> Why not just dup? I've implemented this and it seems to work.
>>
>
> unix keeps the file pointer in the (global) file table. The
> (per-process) file descriptor table references the file table.
>
> opening twice gives you two file descriptor table entries referencing
> two file table entries. duping gives you two file descriptors
> referencing the *same* file table entry. Thus the two fds share the
> file pointer.
>
But opening twice means that you lose coherency with NFS.
I hate Unix.
Regards,
Anthony Liguori
> HTH,
> Gerd
>
>
>
next prev parent reply other threads:[~2008-12-10 18:50 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-05 21:21 [Qemu-devel] [RFC] Replace posix-aio with custom thread pool Anthony Liguori
2008-12-06 9:03 ` Blue Swirl
2008-12-06 18:26 ` Jamie Lokier
2008-12-08 18:23 ` Anthony Liguori
2008-12-09 15:51 ` Gerd Hoffmann
2008-12-09 16:01 ` Anthony Liguori
2008-12-10 16:44 ` Andrea Arcangeli
2008-12-10 17:21 ` Anthony Liguori
2008-12-10 17:29 ` Gerd Hoffmann
2008-12-10 18:50 ` Anthony Liguori [this message]
2008-12-10 19:08 ` Andrea Arcangeli
2008-12-11 13:12 ` Andrea Arcangeli
2008-12-11 15:24 ` Gerd Hoffmann
2008-12-11 15:53 ` Andrea Arcangeli
2008-12-11 16:11 ` Gerd Hoffmann
2008-12-11 16:49 ` Andrea Arcangeli
2008-12-11 17:20 ` Gerd Hoffmann
2008-12-11 18:11 ` Andrea Arcangeli
2008-12-11 20:38 ` Gerd Hoffmann
2008-12-11 20:40 ` Anthony Liguori
2008-12-12 8:23 ` Jens Axboe
2008-12-12 11:51 ` Andrea Arcangeli
2008-12-12 11:54 ` Jens Axboe
2008-12-12 14:13 ` Andrea Arcangeli
2008-12-12 14:24 ` Anthony Liguori
2008-12-12 16:33 ` Chris Wright
2008-12-12 16:51 ` Anthony Liguori
2008-12-12 16:52 ` Chris Wright
2008-12-11 21:32 ` Christoph Hellwig
2008-12-12 0:27 ` Andrea Arcangeli
2008-12-11 21:30 ` Christoph Hellwig
2008-12-11 16:41 ` Anthony Liguori
2008-12-12 14:24 ` Andrea Arcangeli
2008-12-12 14:35 ` Anthony Liguori
2008-12-12 15:44 ` Andrea Arcangeli
2008-12-12 16:49 ` Anthony Liguori
2008-12-12 17:09 ` Andrea Arcangeli
2008-12-12 17:25 ` Anthony Liguori
2008-12-12 17:52 ` Andrea Arcangeli
2008-12-12 18:17 ` Anthony Liguori
2008-12-12 18:26 ` Andrea Arcangeli
2008-12-12 20:12 ` Gerd Hoffmann
2008-12-12 20:17 ` Anthony Liguori
2008-12-12 20:35 ` Gerd Hoffmann
2008-12-09 17:16 ` Avi Kivity
2008-12-17 14:44 ` Ian Jackson
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