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Date: Mon, 13 Feb 2012 07:48:25 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] virtio-blk throughput
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Prateek Sharma <prateek3.14@gmail.com>, qemu-devel@nongnu.org

On 02/13/2012 05:23 AM, Stefan Hajnoczi wrote:
> On Sat, Feb 11, 2012 at 9:57 AM, Prateek Sharma<prateek3.14@gmail.com>  wrote:
>> $QEMU  -cpu core2duo,+vmx  -drive file=$VM_PATH,if=virtio,aio=native
>> -drive file=viotest.img,if=virtio,index=2
>
> -drive cache=none is typically used for good performance when the
> image is on a local disk.  Try that and I think you'll see an
> improvement.

We should throw a bug on aio=native, cache != none.

linux-aio blocks on io_submit if the caching mode isn't O_DIRECT and that will 
kill performance.

Regards,

Anthony Liguori

>
> Stefan
>