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Date: Mon, 15 Mar 2010 15:11:42 +0200
From: Avi Kivity <avi@redhat.com>
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Subject: Re: [Qemu-devel] Ideas wiki for GSoC 2010
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To: Joerg Roedel <joro@8bytes.org>
Cc: Muli Ben-Yehuda <muli@il.ibm.com>, agraf@suse.de, aliguori@us.ibm.com, kvm@vger.kernel.org, jan.kiszka@siemens.com, qemu-devel@nongnu.org, Luiz Capitulino <lcapitulino@redhat.com>, agl@us.ibm.com, Nadav Amit <nadav.amit@gmail.com>, Ben-Ami Yassour1 <benami@il.ibm.com>

On 03/15/2010 03:03 PM, Joerg Roedel wrote:
>
>>> I will add another project - iommu emulation.  Could be very useful
>>> for doing device assignment to nested guests, which could make
>>> testing a lot easier.
>>>        
>> Our experiments show that nested device assignment is pretty much
>> required for I/O performance in nested scenarios.
>>      
> Really? I did a small test with virtio-blk in a nested guest (disk read
> with dd, so not a real benchmark) and got a reasonable read-performance
> of around 25MB/s from the disk in the l2-guest.
>
>    

Your guest wasn't doing a zillion VMREADs and VMWRITEs every exit.

I plan to reduce VMREAD/VMWRITE overhead for kvm, but not much we can do 
for other guests.

-- 
error compiling committee.c: too many arguments to function