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Re: [Qemu-devel] Ideas wiki for GSoC 2010
From: |
Joerg Roedel |
Subject: |
Re: [Qemu-devel] Ideas wiki for GSoC 2010 |
Date: |
Mon, 15 Mar 2010 14:24:48 +0100 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Mon, Mar 15, 2010 at 03:11:42PM +0200, Avi Kivity wrote:
> 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.
Does it matter for the ept-on-ept case? The initial patchset of
nested-vmx implemented it and they reported a performance drop of around
12% between levels which is reasonable. So I expected the loss of
io-performance for l2 also reasonable in this case. My small measurement
was also done using npt-on-npt.
Joerg
- Re: [Qemu-devel] Ideas wiki for GSoC 2010, (continued)
Re: [Qemu-devel] Ideas wiki for GSoC 2010, Muli Ben-Yehuda, 2010/03/15
- Re: [Qemu-devel] Ideas wiki for GSoC 2010, Joerg Roedel, 2010/03/15
- Re: [Qemu-devel] Ideas wiki for GSoC 2010, Avi Kivity, 2010/03/15
- Re: [Qemu-devel] Ideas wiki for GSoC 2010, Anthony Liguori, 2010/03/15
- Re: [Qemu-devel] Ideas wiki for GSoC 2010, Avi Kivity, 2010/03/15
- Re: [Qemu-devel] Ideas wiki for GSoC 2010, Anthony Liguori, 2010/03/15
- Re: [Qemu-devel] Ideas wiki for GSoC 2010, Avi Kivity, 2010/03/16
Re: [Qemu-devel] Ideas wiki for GSoC 2010,
Joerg Roedel <=
Re: [Qemu-devel] Ideas wiki for GSoC 2010, Anthony Liguori, 2010/03/15
Re: [Qemu-devel] Ideas wiki for GSoC 2010, Muli Ben-Yehuda, 2010/03/15