From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: I/O bandwidth control on KVM
Date: Sun, 02 Mar 2008 12:08:39 -0600
Message-ID: <47CAED27.10308@codemonkey.ws>
References: <20080229.210531.226799765.ryov__28298.7898834564$1204287044$gmane$org@valinux.co.jp>
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Cc: kvm-devel@lists.sourceforge.net,
	Ryo Tsuruta <ryov@valinux.co.jp>, dm-devel@redhat.com,
	virtualization <virtualization@lists.linux-foundation.org>
To: Avi Kivity <avi@qumranet.com>
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Avi Kivity wrote:
> Anthony Liguori wrote:
>>
>> If you are using virtio drivers in the guest (which I presume you are 
>> given the reference to /dev/vda), try using the following -drive syntax:
>>
>> -drive file=/dev/mapper/ioband1,if=virtio,boot=on,cache=off
>>
>> This will force the use of O_DIRECT.  By default, QEMU does not open 
>> with O_DIRECT so you'll see page cache effects.
>>
>>   
>
> Good point.  But IIRC cache=off is not limited to virtio?

Nope.  I just wanted to give the exact syntax to use and it looked like 
he was using virtio.

Regards,

Anthony Liguori


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