From: Samuel Thibault <samuel.thibault@eu.citrix.com>
To: "Daniel P. Berrange" <berrange@redhat.com>, qemu-devel@nongnu.org
Cc: Laurent Vivier <Laurent.Vivier@bull.net>
Subject: Re: [Qemu-devel] [PATCH 0/2] Open disk images with O_DIRECT
Date: Wed, 28 Nov 2007 14:34:02 +0000 [thread overview]
Message-ID: <20071128143402.GG4083@implementation.uk.xensource.com> (raw)
In-Reply-To: <20071128142739.GA7379@redhat.com>
Daniel P. Berrange, le Wed 28 Nov 2007 14:27:39 +0000, a écrit :
> On Wed, Nov 28, 2007 at 03:02:50PM +0100, Laurent Vivier wrote:
> > These patches allow to open file using O_DIRECT and bypass the host I/O cache.
> >
> > [PATCH 1/2] Add "directio" parameter to "-drive"
> >
> > Using "directio=on" with "-drive" will open the disk image
> > file using "O_DIRECT".
>
> I don't see the point in adding a config param for this. If it provides a
> useful performance improvement (or other benefit) we should enable it by
> default all the time.
That depends on the mileage of the user. Sometimes it is useful since
it avoids the duplication of page or buffer cache between the guest and
the host, sometimes it is not because the guest is not so i/o friendly
and hence using the host page/buffer cache is useful.
Samuel
next prev parent reply other threads:[~2007-11-28 14:34 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-28 14:02 [Qemu-devel] [PATCH 0/2] Open disk images with O_DIRECT Laurent Vivier
2007-11-28 14:02 ` [Qemu-devel] [PATCH 1/2] Add "directio" parameter to "-drive" Laurent Vivier
2007-11-28 14:02 ` [Qemu-devel] [PATCH 2/2] Direct IDE I/O Laurent Vivier
2007-11-28 14:24 ` [Qemu-devel] [PATCH 1/2] Add "directio" parameter to "-drive" Samuel Thibault
2007-11-28 15:00 ` Laurent Vivier
2007-11-28 15:08 ` Samuel Thibault
2007-11-29 9:40 ` Laurent Vivier
2007-11-28 14:27 ` [Qemu-devel] [PATCH 0/2] Open disk images with O_DIRECT Daniel P. Berrange
2007-11-28 14:34 ` Samuel Thibault [this message]
2007-11-28 14:58 ` Anthony Liguori
2007-11-28 15:08 ` Daniel P. Berrange
2007-11-28 15:17 ` Samuel Thibault
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