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

[Casey DeLorme <cdelorme@xxxxxxxxx>]

Hello Peter,

Question #1: Performance

With x86 Virtualization hardware such as CPU's and Memory are mapped not layered, there should be almost no difference in speeds from running natively.

I am running Windows 7 HVM with an ATI Radeon 6870.  My system has 12GB of RAM, and a Core i7 2600.  I gave Windows 4 vcores and 6GB of memory, Windows Experience index gives me 7.5 for CPU and 7.6 for RAM.  With VGA Passthrough I have 7.8 for both graphics scores.  I am running all my systems on LVM partitions on an OCZ Vertex 3 Drive, without PV Drivers windows scored 6.2 for HDD speeds, with PV drivers it jumped to 7.8.

Scores aside, performance with CPU/RAM is excellent, I am hoping to create a demo video of my system when I get some time (busy with college).

My biggest concern right now is Disk IO ranges from excellent to abysmal, but I have a feeling the displayed values and actual speeds might be different.  I'll put putting together an extensive test with this later, but let's just say IO speeds vary (even with PV drivers).  The Disk IO does not appear to have any affect on games from my experience, so it may only be write speeds.  I have not run any disk benchmarks.

Question #2: GPU Assignment

I have no idea how Dual GPU cards work, so I can't really answer this question.

I can advise you to be on the lookout for motherboards with NF200 chipsets or strange PCI Switches, I bought an ASRock Extreme7 Gen3, great bought but NF200 is completely incompatible with VT-d, ended up with only one PCIe slot to pass.  I can recommend the ASRock Extreme4 Gen3, got it right now, if I had enough money to buy a bigger PSU and a second GPU I would be doing what you are planning to.

Question #3:  Configuration

Two approaches to device connection, USB Passthrough and PCI Passthrough.  I haven't tried USB Passthrough, but I have a feeling it wouldn't work with complex devices that require OS drives, such as BlueTooth receivers or an XBox 360 Wireless adapter.

I took the second approach of passing the USB Controller, but this will vary by hardware.  The ASRock Extreme4 Gen3 has four USB PCI Controllers, I don't have any idea how you would check this stuff from their manuals, I found out when I ran "lspci" from Linux Dom0.

I had no luck with USB 3.0, many devices weren't functional when connected to it, so I left my four USB 3.0 ports to my Dom0, and passed all my USB 2.0 ports.

Again hardware specific, one of the bus had 4 ports, the other had only two, I bought a 4 port USB PCI plate and attached the additional USB pins from the board to turn the 2-port into a 6-port controller.

I use a ton of USB devices on my Windows system, Disk IO blows, but everything else functions great.  With PCI Passed USB I am able to use an XBox 360 Wireless Adapter, 2 Wireless USB Keyboards in different areas of the room, a Hauppauge HD PVR, A logitech C910 HD Webcam, and a Logitech Wireless Mouse.  I had BlueTooth but I got rid of it, the device itself went bad and was causing my system to BlueScreen.

When I tested USB 3.0, I got no video from my Happauge HD PVR or my Logitech C910 webcam, and various devices when connected failed to function right.

Question #4:  Other?

I am 100% certain you could get a system running 2 Windows 7 HVM's up for gaming, but you may need to daisy chain some USB devices if you want more than just a keyboard and mouse for each.

Also, if you are not confident in your ability to work with *nix, I wouldn't advise it.  I had spent two years tinkering with Web Servers in Debian, so I thought I would have an easy time of things.

I tried it on a week off, ended up taking me 2 months to complete my setup.  The results are spectacular, but be prepared to spend many hours debugging unless you find a really good guide.

I would recommend going for a Two Windows on One Rig, and duplicate that rig for a second machine, and I recommend that for two reasons.  If you are successful with the first machine, you can easily copy the process.  This will save you hours of attempting to get a whole four Gaming machines working on one system.

As stated, I only run one gaming machine, but I do have two other HVM's running, one manages my households network and the other is a private web/file server.  So, performance wise Xen can do a lot.

Best of luck,

~Casey

On Fri, May 11, 2012 at 6:17 PM, Peter Vandendriessche <peter.vandendriessche@xxxxxxxxx> wrote:

Hi,

I am new to Xen and I was wondering if the following construction would be feasible with the current Xen.

I would like to put 2/3/4 new computers in my house, mainly for gaming. Instead of buying 2/3/4 different computers, I was thinking of building one computer with a 4/6/8-core CPU, 2/3/4 GPUs, 2/3/4 small SSDs, and attach 2/3/4 monitors to it, 2/3/4 keyboards and 2/3/4 mouses, and run VGA passthrough. This would save me money on hardware, and it would also save quite some space on the desk where I wanted to put them.

If this is possible, I have a few additional questions about this:

1) Would the speed on each virtual machine be effectively that of a 2-core CPU with 1 GPU? What about memory speed/latency?
2) Is it possible to split dual GPUs, e.g. drive 4 OSes with 2x Radeon HD 6990 (=4 GPUs in 2 PCI-e slots)?
3) How should one configure the machine such that each OS receives only the input from its own keyboard/mouse?
4) Any other problems or concerns that you can think of?

Thanks in advance,
Peter


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