[Xen VGA Passthrough] Performance of AMD Radeon HD 6450 in Windows 7 HVM domU Poorer Than in Bare-Metal Windows 8.1 OS

[Xen VGA Passthrough] Performance of AMD Radeon HD 6450 in Windows 7 HVM domU Poorer Than in Bare-Metal Windows 8.1 OS

[Teo En Ming]

Hi,

I have got VGA Passthrough working with AMD Radeon HD 6450.

However, the performance of AMD Radeon HD 6450 in Windows 7 HVM domU is 
poorer than in bare-metal Windows 8.1 operating system. Please refer to 
the 3dmark basic edition 1.3.708 scores for AMD Radeon HD 6450 in both 
Windows 7 HVM domU and bare-metal Windows 8.1.

3dmark scores for Windows 7 HVM domU:

http://www.3dmark.com/3dm/3995208

3dmark scores for bare-metal Windows 8.1:

http://www.3dmark.com/3dm/3996885

Why is there such a great disparity in 3dmark scores for AMD Radeon HD 
6450 in Windows 7 HVM domU and in bare-metal Windows 8.1?

The performance of AMD Radeon HD 6450 in Windows 7 HVM domU is not even 
near native.

Is it possible for developers to improve the performance of AMD Radeon 
HD 6450 in Windows HVM virtual machines?

Thank you very much.

-- 
Yours sincerely,

Teo En Ming
Singapore

Re: [Xen VGA Passthrough] Performance of AMD Radeon HD 6450 in Windows 7 HVM domU Poorer Than in Bare-Metal Windows 8.1 OS

[Gordan Bobic]

Did you test this on a fresh dom0 reboot, i.e. first domU boot
after dom0 reboot?

Also, how many VCPUs do you have in the domU vs. total in the
machine? Can you test bare metal with CPUs disabled? For example,
if you have a quad core CPU, disable 2 cores, test bare metal.
Then start up Xen, limit dom0 to 2 cores, give 2 cores to domU,
test and compare. Also make sure you test with the same OS in
domU and native otherwise you are not really making a meaningful
comparison.

Gordan

On 2014-09-09 16:38, Teo En Ming wrote:
> Hi,
> 
> I have got VGA Passthrough working with AMD Radeon HD 6450.
> 
> However, the performance of AMD Radeon HD 6450 in Windows 7 HVM domU
> is poorer than in bare-metal Windows 8.1 operating system. Please
> refer to the 3dmark basic edition 1.3.708 scores for AMD Radeon HD
> 6450 in both Windows 7 HVM domU and bare-metal Windows 8.1.
> 
> 3dmark scores for Windows 7 HVM domU:
> 
> http://www.3dmark.com/3dm/3995208
> 
> 3dmark scores for bare-metal Windows 8.1:
> 
> http://www.3dmark.com/3dm/3996885
> 
> Why is there such a great disparity in 3dmark scores for AMD Radeon HD
> 6450 in Windows 7 HVM domU and in bare-metal Windows 8.1?
> 
> The performance of AMD Radeon HD 6450 in Windows 7 HVM domU is not
> even near native.
> 
> Is it possible for developers to improve the performance of AMD Radeon
> HD 6450 in Windows HVM virtual machines?
> 
> Thank you very much.

Re: [Xen VGA Passthrough] Performance of AMD Radeon HD 6450 in Windows 7 HVM domU Poorer Than in Bare-Metal Windows 8.1 OS

[Teo En Ming]

On 09/09/2014 23:49, Gordan Bobic wrote:
> Did you test this on a fresh dom0 reboot, i.e. first domU boot
> after dom0 reboot?

Yes.

>
> Also, how many VCPUs do you have in the domU vs. total in the
> machine? 

I have 4 VCPUs in the domU and 4 cores in the machine.

> Can you test bare metal with CPUs disabled? For example,
> if you have a quad core CPU, disable 2 cores, test bare metal.

How do I do that?
>
> Then start up Xen, limit dom0 to 2 cores, give 2 cores to domU,
> test and compare. 

4 cores were automatically assigned to dom0. I gave 4 cores to domU as well.

> Also make sure you test with the same OS in
> domU and native otherwise you are not really making a meaningful
> comparison.
>
> Gordan
>
> On 2014-09-09 16:38, Teo En Ming wrote:
>> Hi,
>>
>> I have got VGA Passthrough working with AMD Radeon HD 6450.
>>
>> However, the performance of AMD Radeon HD 6450 in Windows 7 HVM domU
>> is poorer than in bare-metal Windows 8.1 operating system. Please
>> refer to the 3dmark basic edition 1.3.708 scores for AMD Radeon HD
>> 6450 in both Windows 7 HVM domU and bare-metal Windows 8.1.
>>
>> 3dmark scores for Windows 7 HVM domU:
>>
>> http://www.3dmark.com/3dm/3995208
>>
>> 3dmark scores for bare-metal Windows 8.1:
>>
>> http://www.3dmark.com/3dm/3996885
>>
>> Why is there such a great disparity in 3dmark scores for AMD Radeon HD
>> 6450 in Windows 7 HVM domU and in bare-metal Windows 8.1?
>>
>> The performance of AMD Radeon HD 6450 in Windows 7 HVM domU is not
>> even near native.
>>
>> Is it possible for developers to improve the performance of AMD Radeon
>> HD 6450 in Windows HVM virtual machines?
>>
>> Thank you very much.
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
>


-- 
Yours sincerely,

Teo En Ming

Re: [Xen VGA Passthrough] Performance of AMD Radeon HD 6450 in Windows 7 HVM domU Poorer Than in Bare-Metal Windows 8.1 OS

[Zytaruk, Kelly]

Hi Teo,

It is difficult to compare scores between Win7 running in DomU and Win8.1 running on bare metal.  A more comprehensive comparison would be to compare Win7 in DomU versus Win7 on bare metal.

I currently test with 3DMark11 version 1.0.132.0.  I will download a copy of 1.3.708 and see what kind of results I get.

I had a quick look at the scores and as you mention, there is a significant difference.  What driver are you using for Win8.1 as I see the results showing "Graphics driver is not approved".

It would also be useful to know which version of Xen and Linux you are using.

While I will try to help you as much as I can, we also have a user forum at forums.amd.com where you can speak with others that may have seen the same issues as you. This forum is also monitored by our customer support team and they would very much like to hear your feedback.

Thanks,
Kelly

> -----Original Message-----
> From: Teo En Ming [mailto:singapore.mr.teo.en.ming@gmail.com]
> Sent: Tuesday, September 09, 2014 11:39 AM
> To: xen-devel@lists.xen.org; Zytaruk, Kelly; Teo En Ming (Zhang Enming)
> Subject: [Xen VGA Passthrough] Performance of AMD Radeon HD 6450 in
> Windows 7 HVM domU Poorer Than in Bare-Metal Windows 8.1 OS
> 
> Hi,
> 
> I have got VGA Passthrough working with AMD Radeon HD 6450.
> 
> However, the performance of AMD Radeon HD 6450 in Windows 7 HVM domU
> is poorer than in bare-metal Windows 8.1 operating system. Please refer to the
> 3dmark basic edition 1.3.708 scores for AMD Radeon HD 6450 in both Windows
> 7 HVM domU and bare-metal Windows 8.1.
> 
> 3dmark scores for Windows 7 HVM domU:
> 
> http://www.3dmark.com/3dm/3995208
> 
> 3dmark scores for bare-metal Windows 8.1:
> 
> http://www.3dmark.com/3dm/3996885
> 
> Why is there such a great disparity in 3dmark scores for AMD Radeon HD
> 6450 in Windows 7 HVM domU and in bare-metal Windows 8.1?
> 
> The performance of AMD Radeon HD 6450 in Windows 7 HVM domU is not even
> near native.
> 
> Is it possible for developers to improve the performance of AMD Radeon HD
> 6450 in Windows HVM virtual machines?
> 
> Thank you very much.
> 
> --
> Yours sincerely,
> 
> Teo En Ming
> Singapore

Re: [Xen VGA Passthrough] Performance of AMD Radeon HD 6450 in Windows 7 HVM domU Poorer Than in Bare-Metal Windows 8.1 OS

[Gordan Bobic]

On 2014-09-09 17:51, Teo En Ming wrote:
> On 09/09/2014 23:49, Gordan Bobic wrote:

>> Also, how many VCPUs do you have in the domU vs. total in the
>> machine?
> 
> I have 4 VCPUs in the domU and 4 cores in the machine.

A 25-40% drop from virtualization overheads isn't unheard of.
If some parts of the benchmark are CPU bound such a drop
wouldn't be particularly unusual.

>> Can you test bare metal with CPUs disabled? For example,
>> if you have a quad core CPU, disable 2 cores, test bare metal.
> 
> How do I do that?

See if your BIOS has an option for it. I'm not sure if there
is a way to make Windows itself ignore some cores.

>> Then start up Xen, limit dom0 to 2 cores, give 2 cores to domU,
>> test and compare.
> 
> 4 cores were automatically assigned to dom0. I gave 4 cores to domU as 
> well.

So limit dom0 to 2 cores, and give 2 cores to domU. Ideally pin
dom0 to the first 2 (0,1) and limit domU to the other 2 (2,3).