Re: [Qemu-devel] Ideas wiki for GSoC 2010

Avi Kivity
2010-03-15T13:11:56Z

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.

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