Re: [Xen-users] gaming on multiple OS of the same machine?

[Andrew Bobulsky <rulerof@xxxxxxxxx>]

Hello again,

On Sun, May 20, 2012 at 6:30 PM, Peter Vandendriessche
<peter.vandendriessche@xxxxxxxxx> wrote:
> Hi Andrew,
>
> On Sun, May 20, 2012 at 4:30 PM, Andrew Bobulsky <rulerof@xxxxxxxxx> wrote:
>>
>> With that in mind, I'm going to suggest below a
>> modified (from my setup) AMD-based build containing a board/CPU that I
>> have tested and can confirm works with PCIe passthrough on Xen.... but
>> not with 4 video cards.
>
>
> Not tested with 4 video cards, or not working with 4 video cards? If not
> working, what exactly makes it fail? From the pic I would deduce that you
> are doing a full 4-machine setup...

Heh, shoulda been more specific: Gigabyte board, I've not /tested/
with 4 video cards.  There's no reason that it shouldn't work just
fine though.  MSI Board tested and working fine with 4 video cards.

(Also: As the picture implies, my setup is a fully-working four-headed
rig, though I don't operate all four heads simultaneously right now
because I simply don't need the fourth seat, and because I don't feel
that I have enough CPU horsepower for it.  Keep reading for more on
that.  Academically speaking, the point is that it works!)

>> I *would* suggest the board that I currently use (the MSI
>> 890FXA-GD70), it required a BIOS downgrade for me to get IOMMU to
>> work... which would probably break compatibility with the CPU I'm
>> going to suggest.  Perhaps that's been fixed in the year since I
>> discovered the problem, but I have no idea :P
>
>
> That's a pity... what CPU have you put in it to make it work then?

I'm running that board with a Phenom II X6 1090T.  While I have had
all four guests online at the same time, I haven't run them all with a
full load (i.e. gaming) simultaneously on the 6 core CPU.  I moved to
the 6 core because I had the chip available (moved from a different
system) when the 4 core CPU began to struggle once the project
progressed to bringing the third seat online.

It's worth keeping in mind that this project evolved for me over a
very long period of time, and my recommendations are, in some
respects, a "best of" the experiences I've had.

With that in mind....

>>
>> Motherboard: Gigabyte GA-990FXA-UD7 (
>> http://www.newegg.com/Product/Product.aspx?Item=N82E16813128508 )
>
> This is not the same one as the 890FXA-GD70 you suggested earlier. Is there
> a reason to prefer either one? And is this one compatible with said CPU
> without BIOS upgrade?

I'm not certain if the 1.8 BIOS on the MSI 890FXA-GD70 will support
the 8-core CPU or not, nor do I know whether or not any BIOS revision
does.  If such a BIOS update *does* exist, I don't know whether or not
MSI fixed whatever they did to break IOMMU with BIOS revisions
following v1.8.

The suggestions I've outlined are based on the assumption that an
8-core CPU is non-negotiable as far as hardware goes.  On the AMD
side, the choices of available CPU /may/ specifically preclude the MSI
board.

I know for a fact though that the Gigabyte GA-990FXA-UD7, with the
8-core AMD chip in it will boot, and it does support IOMMU.  I've got
such a setup sitting on one of my desks, where I'm tinkering with
it... but it belongs to a buddy of mine.  If it were mine, I'd
actually be attempting to assemble specifically the hardware setup
I've outlined, as it's technically a superset of what I have
immediately available to me :)

In summary:

I own and have built a four-seat gaming rig on the MSI 890FXA-GD70.  I
/do not/ recommend you acquire the same, and instead suggest you build
on the Gigabyte GA-990FXA-UD7, because I know it will support the AMD
8-core CPU in addition to IOMMU, and have tested such.

If you're looking to have more of a guarantee of success by building
your own setup based as closely as possible on the platform I'm
running for my build, I can look into the matter of whether or not
there is a BIOS update for the MSI board that claims to support the
8-core chip, and then can flash that against my hardware and test to
see if IOMMU works properly.  I can do that in the coming days.

I really don't want to disassemble two systems to physically test the
chip in the board as well... removing the CPU from that thing is a
nightmare.  The PCIe retention clips make it so you have to take all
the cards out in reverse order... then there's the power connectors...
and so on.  Really a nightmare.  It's worth pointing out that the
Gigabyte board improves somewhat on that with more forgiving retention
clips as far as I can tell, but that's not a criterion for choosing
hardware here ;)


>> I'm not too sure if I missed anything... it's taken a while to write
>> this, but I'm hoping it's pretty comprehensive!
>
>
> It's wonderful. You're an angel! :)
>
>
> Best regards,
> Peter

I'm thoroughly excited that someone else is trying to do this.  I'll
endeavor to be as helpful as I can!  Please feel free to continue with
any questions you may have, and I'll do my best.  I should be able to
carry out any testing that may be needed throughout the course of the
week.

Cheers,
Andrew Bobulsky

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