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From: Avi Kivity <avi@redhat.com>
To: Asdo <asdo@shiftmail.org>
Cc: Antoine Martin <antoine@nagafix.co.uk>,
	Christoph Hellwig <hch@infradead.org>,
	Michael Tokarev <mjt@tls.msk.ru>,
	kvm@vger.kernel.org
Subject: Re: raw disks no longer work in latest kvm (kvm-88 was fine)
Date: Sun, 07 Mar 2010 21:12:37 +0200	[thread overview]
Message-ID: <4B93FAA5.6010803@redhat.com> (raw)
In-Reply-To: <4B93F9E6.2050301@shiftmail.org>

On 03/07/2010 09:09 PM, Asdo wrote:
> Avi Kivity wrote:
>> On 03/07/2010 08:01 PM, Antoine Martin wrote:
>>>
>>> Yes cache=none: "-drive file=./vm/var_fs,if=virtio,cache=none"
>>>
>>> Side question: this is the right thing to do for raw partitions, right?
>>
>> The rightest.
>
> Isn't cache=writeback now safe on virtio-blk since 2.6.32?

Yes.

> Doesn't it provide better performances?

No.  The guest will do its own caching, so unless the guest is really 
short of memory, you aren't gaining much; and the copying will hurt.

>
> Also that looks like a raw file to me, not a partition... do they 
> follow the same optimization "rule"?

More or less.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


  parent reply	other threads:[~2010-03-07 19:12 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-06 20:48 raw disks no longer work in latest kvm (kvm-88 was fine) Antoine Martin
2010-03-06 21:28 ` Michael Tokarev
2010-03-07  4:14   ` Antoine Martin
2010-03-07  9:32     ` Michael Tokarev
2010-03-07 10:00       ` Christoph Hellwig
2010-03-07 13:12         ` Antoine Martin
2010-03-07 13:52           ` Antoine Martin
2010-03-07 15:15             ` Michael Tokarev
2010-03-07 17:11               ` Antoine Martin
2010-03-07 17:18                 ` Avi Kivity
2010-03-07 17:21                   ` Christoph Hellwig
2010-03-07 17:30                     ` Avi Kivity
2010-03-07 17:34                       ` Christoph Hellwig
2010-03-07 18:43                         ` raw disks no longer work in latest kvm (kvm-88 was fine) [SOLVED] Antoine Martin
2010-03-07 18:55                           ` Avi Kivity
2010-03-07 18:01                       ` raw disks no longer work in latest kvm (kvm-88 was fine) Antoine Martin
2010-03-07 18:47                         ` Avi Kivity
2010-03-07 19:07                           ` Antoine Martin
2010-03-07 19:10                             ` Avi Kivity
2010-03-07 19:13                               ` Antoine Martin
2010-03-07 19:17                                 ` Avi Kivity
2010-03-07 19:25                                   ` Antoine Martin
2010-03-07 19:35                                     ` Avi Kivity
2010-03-13  9:51                                       ` Antoine Martin
2010-03-14  7:34                                         ` Avi Kivity
2010-04-08 22:00                                         ` Antoine Martin
2010-05-22 10:44                                           ` Antoine Martin
2010-05-22 11:17                                             ` Michael Tokarev
2010-05-22 11:35                                               ` Antoine Martin
2010-05-23  8:53                                                 ` Antoine Martin
2010-05-23 11:57                                                   ` Avi Kivity
2010-05-23 14:07                                                     ` Antoine Martin
2010-05-23 14:18                                                       ` Avi Kivity
2010-05-23 14:43                                                         ` Antoine Martin
2010-05-23 14:53                                                           ` Antoine Martin
2010-05-23 14:56                                                             ` Avi Kivity
2010-05-23 15:06                                                           ` Antoine Martin
2010-05-23 15:12                                                           ` Avi Kivity
2010-05-23 16:18                                                             ` Antoine Martin
2010-05-23 17:47                                                               ` Stefan Hajnoczi
2010-05-29  9:42                                                                 ` Antoine Martin
2010-05-29  9:55                                                                   ` Stefan Hajnoczi
2010-05-29 10:34                                                                     ` Christoph Hellwig
2010-05-29 11:06                                                                       ` Stefan Hajnoczi
2010-05-29 10:34                                                                   ` Christoph Hellwig
2010-03-07 19:09                           ` Asdo
2010-03-07 19:11                             ` Antoine Martin
2010-03-07 19:12                             ` Avi Kivity [this message]
2010-03-07 16:21         ` Avi Kivity
2010-03-08 16:45           ` Anthony Liguori
2010-03-07  9:36 ` Gleb Natapov

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