peter.vandendriessche at gmail
May 15, 2012, 4:50 AM
Views: 1245
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Re: gaming on multiple OS of the same machine?
[In reply to]
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Test... has the e-mail below reached the mailing list? It's not in the
archives and I got a message that something of me was rejected (saying I'm
not a member... whut?), so I'll send it again.
On Mon, May 14, 2012 at 11:52 PM, Peter Vandendriessche <
peter.vandendriessche [at] gmail> wrote:
> Hi Casey,
>
> Thanks a lot for the bunch of information. Some further questions on the
> PLX and the VGA passthrough though.
>
>
> On Sun, May 13, 2012 at 8:42 PM, Casey DeLorme <cdelorme [at] gmail> wrote:
>
>> I checked every major manufacturers high end boards, searching for one
>> with the best features to price and was aiming for the most PCIe slots I
>> could get. Pretty much Every single board with more than 3 PCIe (x16)
>> slots came with some form of PCI switch. Most of these PCI switches break
>> IOMMU in one way or another.
>>
>
> Yes, indeed, all of the 4-GPU-motherboards I know, have 2 PCI-e x16 slots
> which split to 2 x8 each (so 4 x8 in total). Is this always a fatal
> problem? Is there any easy way to find out if it will be a problem (like
> from the lspci info)?
>
>
> The PLX was an entirely different form of problem, it merges device
>> "function" with device identifiers. If you run "lspci" you get a list of
>> your devices, they are identified by "bus:device.function".
>> [...]
>>
>> Armed with this knowledge, here is where you may run into problems:
>> - Finding a board with 4x PCIe x16 Slots not tied to a PCI Switch
>>
>
> So, do I understand correct that it will work if and only if there is 1
> "bus" per PCI-e slot?
>
>
> - Sparing enough USB ports for all machines input devices
>
>
> What do you mean by sparing here? On a different bus than the PCI-e slots
> for the GPUs?
>
>
> - Limited to around 3GB of RAM per HVM unless you buy 8GB RAM Chips
>>
>
> Neither seems a problem (3GB RAM per machine or 8GB RAM chips). The price
> of RAM is fairly linear in its size.
>
>
> - Will need a 6-core i7 to power all systems without potential resource
>> conflicts
>>
>
> Okay. That rises the price a bit, but it'd still be well worth it.
>
>
> - Encountering bugs nobody else has when you reach that 3rd or 4th HVM
>>
>
> This would probably be the real problem, given that I'm new to Xen.
>
>
> I have never run more than one GPU in my computers before, so I don't know
>> if there is some special magic that happens when you have two or more that
>> they suddenly get even hotter, but I have to imagine that not to be the
>> case unless you're doing some serious overclocking.
>
>
> Depends on their size. Most GPUs are 2 PCI-e slots high (and occupy two of
> those metal plates on the back) and hence plugging 4 of them in leaves no
> space inbetween them, which hinders their air intake. Hence the need for
> watercooling the GPUs in this case.
>
>
> The ASRock Extreme4 Gen3 does have enough PCIe slots that I could connect
>> three GPU's and still have space for a single-slot PCIe device, but I only
>> have a 650W power supply, and have no need for more than one Windows
>> instance.
>>
>
> ... and it has a PLX chip. Right? Or is a PLX chip not a fatal problem?
>
>
> Secondary pass through works great for gaming, shows the display after the
>> machine boots without any problems, and takes literally no extra effort to
>> setup on your part.
>>
>> Primary passthrough requires custom ATI patching, and what exists may not
>> work for all cards.
>>
>> I began looking into Primary passthrough very recently, because I use my
>> machine for more than just games and ran into a problem. Software like
>> CAD, Photoshop, and 3D Sculpting tools use OpenGL and only work with the
>> primary GPU, which means they either don't run or run without GPU
>> acceleration (slowly).
>>
>
> Hmm? I'm not following. Most games also use OpenGL, right? And why would
> OpenGL not support non-primary cards? I know that OpenCL can run on any
> number of GPUs, so it'd surprise me if OpenGL was different. Do you have
> any link where I can read more background on this?
>
>
>
>> A lot to take in, but I hope my answers help a bit. If you have more
>> questions I'll be happy to share what knowledge I can.
>>
>
> Certainly, they're of great help. Thanks a lot!
>
> Best regards,
> Peter
>
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