From: Avi Kivity <avi@redhat.com>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Chris Wright <chrisw@redhat.com>,
Mark McLoughlin <markmc@redhat.com>,
kvm-devel <kvm-devel@lists.sourceforge.net>,
Laurent Vivier <Laurent.Vivier@bull.net>,
qemu-devel@nongnu.org, Ryan Harper <ryanh@us.ibm.com>
Subject: Re: [Qemu-devel] [RFC] Disk integrity in QEMU
Date: Tue, 14 Oct 2008 17:43:50 +0200 [thread overview]
Message-ID: <48F4BE36.9040309@redhat.com> (raw)
In-Reply-To: <48F4BB93.5030709@codemonkey.ws>
Anthony Liguori wrote:
> Avi Kivity wrote:
>> I don't think O_DIRECT should be qemu's default, since anyone using qemu
>> directly is likely a "causal virtualization" user. Management systems
>> like ovirt should definitely default to O_DIRECT (really, they shouldn't
>> even offer caching).
>>
>
> ovirt isn't a good example because the default storage model is
> iSCSI. Since you aren't preserving zero-copy, I doubt that you'll see
> any advantage to using O_DIRECT (I suspect the code paths aren't even
> different).
If you have a hardware iSCSI initiator then O_DIRECT pays off. Even for
a software initiator, the write path could be made zero copy. The read
path doesn't look good though.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
next prev parent reply other threads:[~2008-10-14 15:44 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-09 17:00 [Qemu-devel] [RFC] Disk integrity in QEMU Anthony Liguori
2008-10-10 7:54 ` Gerd Hoffmann
2008-10-10 8:12 ` Mark McLoughlin
2008-10-12 23:10 ` Jamie Lokier
2008-10-14 17:15 ` Avi Kivity
2008-10-10 9:32 ` Avi Kivity
2008-10-12 23:00 ` Jamie Lokier
2008-10-10 8:11 ` Aurelien Jarno
2008-10-10 12:26 ` Anthony Liguori
2008-10-10 12:53 ` Paul Brook
2008-10-10 13:55 ` Anthony Liguori
2008-10-10 14:05 ` Paul Brook
2008-10-10 14:19 ` Avi Kivity
2008-10-17 13:14 ` Jens Axboe
2008-10-19 9:13 ` Avi Kivity
2008-10-10 15:48 ` Aurelien Jarno
2008-10-10 9:16 ` Avi Kivity
2008-10-10 9:58 ` Daniel P. Berrange
2008-10-10 10:26 ` Avi Kivity
2008-10-10 12:59 ` Paul Brook
2008-10-10 13:20 ` Avi Kivity
2008-10-10 12:34 ` Anthony Liguori
2008-10-10 12:56 ` Avi Kivity
2008-10-11 9:07 ` andrzej zaborowski
2008-10-11 17:54 ` Mark Wagner
2008-10-11 20:35 ` Anthony Liguori
2008-10-12 0:43 ` Mark Wagner
2008-10-12 1:50 ` Chris Wright
2008-10-12 1:50 ` Chris Wright
2008-10-12 16:22 ` Jamie Lokier
2008-10-12 16:22 ` Jamie Lokier
2008-10-12 17:54 ` Anthony Liguori
2008-10-12 18:14 ` nuitari-qemu
2008-10-13 0:27 ` Mark Wagner
2008-10-13 1:21 ` Anthony Liguori
2008-10-13 2:09 ` Mark Wagner
2008-10-13 3:16 ` Anthony Liguori
2008-10-13 6:42 ` Aurelien Jarno
2008-10-13 14:38 ` Steve Ofsthun
2008-10-12 0:44 ` Chris Wright
2008-10-12 10:21 ` Avi Kivity
2008-10-12 14:37 ` Dor Laor
2008-10-12 14:37 ` Dor Laor
2008-10-12 15:35 ` Jamie Lokier
2008-10-12 18:00 ` Anthony Liguori
2008-10-12 18:02 ` Anthony Liguori
2008-10-12 18:02 ` Anthony Liguori
2008-10-15 10:17 ` Andrea Arcangeli
2008-10-15 10:17 ` Andrea Arcangeli
2008-10-12 17:59 ` Anthony Liguori
2008-10-12 18:34 ` Avi Kivity
2008-10-12 19:33 ` Izik Eidus
2008-10-12 19:33 ` Izik Eidus
2008-10-14 17:08 ` Avi Kivity
2008-10-14 17:08 ` Avi Kivity
2008-10-12 19:59 ` Anthony Liguori
2008-10-12 20:43 ` Avi Kivity
2008-10-12 21:11 ` Anthony Liguori
2008-10-14 15:21 ` Avi Kivity
2008-10-14 15:32 ` Anthony Liguori
2008-10-14 15:43 ` Avi Kivity [this message]
2008-10-14 19:25 ` Laurent Vivier
2008-10-16 9:47 ` Avi Kivity
2008-10-12 10:12 ` Avi Kivity
2008-10-17 13:20 ` Jens Axboe
2008-10-19 9:01 ` Avi Kivity
2008-10-19 18:10 ` Jens Axboe
2008-10-19 18:23 ` Avi Kivity
2008-10-19 19:17 ` M. Warner Losh
2008-10-19 19:31 ` Avi Kivity
2008-10-19 18:24 ` Avi Kivity
2008-10-19 18:36 ` Jens Axboe
2008-10-19 19:11 ` Avi Kivity
2008-10-19 19:30 ` Jens Axboe
2008-10-19 20:16 ` Avi Kivity
2008-10-20 14:14 ` Avi Kivity
2008-10-10 10:03 ` Fabrice Bellard
2008-10-13 16:11 ` Laurent Vivier
2008-10-13 16:58 ` Anthony Liguori
2008-10-13 17:36 ` Jamie Lokier
2008-10-13 17:06 ` [Qemu-devel] " Ryan Harper
2008-10-13 18:43 ` Anthony Liguori
2008-10-14 16:42 ` Avi Kivity
2008-10-13 18:51 ` Laurent Vivier
2008-10-13 19:43 ` Ryan Harper
2008-10-13 20:21 ` Laurent Vivier
2008-10-13 21:05 ` Ryan Harper
2008-10-15 13:10 ` Laurent Vivier
2008-10-16 10:24 ` Laurent Vivier
2008-10-16 13:43 ` Anthony Liguori
2008-10-16 16:08 ` Laurent Vivier
2008-10-17 12:48 ` Avi Kivity
2008-10-17 13:17 ` Laurent Vivier
2008-10-14 10:05 ` Kevin Wolf
2008-10-14 14:32 ` Ryan Harper
2008-10-14 16:37 ` Avi Kivity
2008-10-13 19:00 ` Mark Wagner
2008-10-13 19:15 ` Ryan Harper
2008-10-14 16:49 ` Avi Kivity
2008-10-13 17:58 ` [Qemu-devel] " Rik van Riel
2008-10-13 18:22 ` Jamie Lokier
2008-10-13 18:34 ` Rik van Riel
2008-10-14 1:56 ` Jamie Lokier
2008-10-14 2:28 ` nuitari-qemu
2008-10-28 17:34 ` Ian Jackson
2008-10-28 17:45 ` Anthony Liguori
2008-10-28 17:50 ` Ian Jackson
2008-10-28 18:19 ` Jamie Lokier
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