From: Jamie Lokier <jamie@shareable.org>
To: Laurent Vivier <Laurent.Vivier@bull.net>
Cc: Blue Swirl <blauwirbel@gmail.com>,
qemu-devel@nongnu.org, Kevin Wolf <kwolf@suse.de>
Subject: Re: [Qemu-devel] Re: [PATCH][v2] Align file accesses with cache=off (O_DIRECT)
Date: Wed, 21 May 2008 00:13:03 +0100 [thread overview]
Message-ID: <20080520231303.GJ27853@shareable.org> (raw)
In-Reply-To: <1211324687.4217.8.camel@frecb07144>
Laurent Vivier wrote:
> Sector unaligned guest offset are converted to sector aligned offset.
The guest cannot give a sector unaligned offset. How can it? It
specifies offset in sectors, through the IDE or SCSI interfaces.
> Sector aligned guest offset are written as is.
>
> And as we use O_DIRECT and aligned offset and data count I think we
> increase disk integrity (regarding the case without O_DIRECT and without
> aligned access...), so we should document the case without O_DIRECT use,
> not the case with O_DIRECT use...
That's fine, for direct-mapped formats. I'm thinking of qcow format
etc. where guest aligned writes are sometimes translated to unaligned
(is this even true?).
-- Jamie
next prev parent reply other threads:[~2008-05-20 23:13 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-20 11:32 [Qemu-devel] [PATCH][v2] Align file accesses with cache=off (O_DIRECT) Laurent Vivier
2008-05-20 19:47 ` [Qemu-devel] " Anthony Liguori
2008-05-20 22:36 ` Jamie Lokier
2008-05-20 22:52 ` Paul Brook
2008-05-20 22:59 ` Laurent Vivier
2008-05-21 0:54 ` Paul Brook
2008-05-21 7:59 ` Laurent Vivier
2008-05-21 0:58 ` Anthony Liguori
2008-05-21 1:04 ` Jamie Lokier
2008-05-21 1:05 ` Anthony Liguori
2008-05-21 8:06 ` Kevin Wolf
2008-05-21 1:05 ` Paul Brook
2008-05-21 1:14 ` Anthony Liguori
2008-05-21 8:24 ` Kevin Wolf
2008-05-21 12:26 ` Jamie Lokier
2008-05-21 12:37 ` Avi Kivity
2008-05-21 13:41 ` Jamie Lokier
2008-05-21 13:55 ` Anthony Liguori
2008-05-21 14:17 ` Avi Kivity
2008-05-21 14:26 ` Anthony Liguori
2008-05-21 14:57 ` Avi Kivity
2008-05-21 15:34 ` Jamie Lokier
2008-05-21 16:02 ` Anthony Liguori
2008-05-21 16:24 ` Jamie Lokier
2008-05-21 16:48 ` Avi Kivity
2008-05-21 17:01 ` Andrea Arcangeli
2008-05-21 17:18 ` Avi Kivity
2008-05-21 17:47 ` Andrea Arcangeli
2008-05-21 17:53 ` Anthony Liguori
2008-05-21 18:08 ` Andrea Arcangeli
2008-05-21 18:25 ` Anthony Liguori
2008-05-21 20:13 ` Andrea Arcangeli
2008-05-21 20:35 ` Anthony Liguori
2008-05-21 20:42 ` Andrea Arcangeli
2008-05-21 18:29 ` Avi Kivity
2008-05-21 16:45 ` Avi Kivity
2008-05-21 16:44 ` Avi Kivity
2008-05-20 23:04 ` Laurent Vivier
2008-05-20 23:13 ` Jamie Lokier [this message]
2008-05-21 1:00 ` Anthony Liguori
2008-05-21 1:19 ` Jamie Lokier
2008-05-21 2:12 ` Anthony Liguori
2008-05-21 8:27 ` Andreas Färber
2008-05-21 14:06 ` Anthony Liguori
2008-05-21 15:31 ` Jamie Lokier
2008-05-21 11:43 ` Jamie Lokier
2008-05-23 9:12 ` Laurent Vivier
2008-05-28 7:01 ` Kevin Wolf
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