From: Paul Brook <paul@codesourcery.com>
To: qemu-devel@nongnu.org
Cc: Samuel Thibault <samuel.thibault@eu.citrix.com>
Subject: Re: [Qemu-devel] [PATCH 2/2 v2] Direct IDE I/O
Date: Mon, 3 Dec 2007 17:17:23 +0000 [thread overview]
Message-ID: <200712031717.24596.paul@codesourcery.com> (raw)
In-Reply-To: <20071203170800.GC3797@implementation>
On Monday 03 December 2007, Samuel Thibault wrote:
> Anthony Liguori, le Mon 03 Dec 2007 09:54:47 -0600, a écrit :
> > Have you done any performance testing? Buffered IO should absolutely
> > beat direct IO simply because buffered IO allows writes to complete
> > before they actually hit disk.
>
> Since qemu can use the aio interface, that shouldn't matter.
Only if the emulated hardware and guest OS support multiple concurrent
commands. IDE supports async operation, but not concurrent commmands. In
practice this means you only get full performance if you're using the SCSI
emulation.
Paul
next prev parent reply other threads:[~2007-12-03 17:17 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-03 10:09 [Qemu-devel] [PATCH 0/2 v2] Open disk images with O_DIRECT Laurent Vivier
2007-12-03 10:09 ` [Qemu-devel] [PATCH 1/2 v2] Add "cache" parameter to "-drive" Laurent Vivier
2007-12-03 10:09 ` [Qemu-devel] [PATCH 2/2 v2] Direct IDE I/O Laurent Vivier
2007-12-03 10:23 ` Fabrice Bellard
2007-12-03 10:30 ` Laurent Vivier
2007-12-03 11:40 ` Markus Hitter
2007-12-03 15:39 ` Paul Brook
2007-12-03 19:26 ` Samuel Thibault
2007-12-03 15:54 ` Anthony Liguori
2007-12-03 17:08 ` Samuel Thibault
2007-12-03 17:17 ` Paul Brook [this message]
2007-12-03 17:49 ` Jamie Lokier
2007-12-03 18:08 ` Anthony Liguori
2007-12-03 18:40 ` Jamie Lokier
2007-12-03 18:06 ` Anthony Liguori
2007-12-03 19:10 ` Laurent Vivier
2007-12-03 19:16 ` Paul Brook
2007-12-03 21:36 ` Anthony Liguori
2007-12-04 12:49 ` Gerd Hoffmann
2007-12-04 13:02 ` Laurent Vivier
2007-12-04 8:13 ` Laurent Vivier
2007-12-03 21:13 ` Gerd Hoffmann
2007-12-03 21:23 ` Samuel Thibault
2007-12-03 21:38 ` Anthony Liguori
2007-12-04 13:21 ` Gerd Hoffmann
2007-12-04 15:03 ` Anthony Liguori
2007-12-04 16:18 ` Gerd Hoffmann
2007-12-05 14:47 ` Anthony Liguori
2007-12-03 19:14 ` Paul Brook
2007-12-03 19:00 ` Laurent Vivier
2007-12-03 11:14 ` Johannes Schindelin
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