Xen Hypervisor, How good is it for gaming?

So in arch or fedora how good is Xen? My specs are as follows

Core i5 2500 3.3, XFX 6870 1GB, G1 Sniper M3, 8GB Vengeance 1600Mhz RAM.

Ideas on how it would perform? I know it doesnt work like a VM as such, the fact it has direct access to my hardware, but will having an OS run and OS running games affect the FPS?

Thanks :)

You don't need to use Xen (which is commercial), but you can use kvm (which is open source and in your case will perform better).

The benefit of commercial virtualization solutions (even if they are free to use and mostly open source, they are not really free as in libre and open source because they are licensed) is there when users that don't have compatible hardware want to have better paravirtualized graphics in the guest OS. In your case, there is a very easy kvm solution. The i5-2500 non-k has VT-d support and an iGPU, which means that you can use kvm and set up a PCI passthrough from your guest OS to your graphics card (instead of VGA passthrough, which requires some tinkering), because you can use the iGPU and a second cable to your monitor to switch between the screen of the host and the guest. It's very easy to do in virt-manager, no CLI required. You then switch between the screen of the host and the guest by selecting the input channel on your monitor. Such a PCI passthrough, just like a VGA passthrough, will give you better performance in games in a windows guest than on a bare metal install, and more system flexibility.

Okay, what about what you said about fooling the system into thinking its an 8 core? Will i need HTs? as known the i5 doesnt have HT, or do i edit the options in the KVM? Also whats the FPS like in the machine? I play stuff like simcity and Call of duty.

You can edit the processor model and topology in virt-manager. If you don't emulate a different family of processors, you won't lose performance. You can however emulate any processor you like. If you don't emulate another family of processors, you just change the processor topology to 8-core, it will work just fine.

No CLI is required, you can do everything in the virt-manager GUI.

fps is 10-30 % higher in a linux-hosted kvm windows guest than on a bare metal machine with the same hardware. That is with PCI or VGA passthrough. There are almost no games that take an fps punishment, but it can happen. Some games have a much greater boost in performance, depending on the distro and the general system configuration. To have more performance, you have to keep your linux install as clean as possible, no closed source crap, no skype (works better on a phone anyway), no flash (html5 uses much less resources and has better quality and no DRM in linux, whereas Adobe flash player introduces DRM in linux), etc... just no shortcuts but conscious system configuration, netfilters up, SELinux enforcing, only official license-free and pure FOSS repos (except maybe for some "bad" codecs from an official repo), just everything shut tight for maximum hygiene, a good repo (nothing Ubuntu based, best to stick to Gentoo, Arch or Fedora, or Debian or Slackware if you don't like modern kernels and don't mind solving problems that exist only out of principle). Discipline pays off, keep your system clean and the sky is the limit, step in a honey trap and you're screwed, it's as simple as that.

Simcity and COD both run in wine, you don't even need windows for that. You'll need Windows dll's and some wine config tinkering, but when it's configured right, CoD4 and 5 gain about 10-15 % of fps in wine in comparison to a bare metal windows install, which is about the same as the fps gain you get in a VGA passthrough kvm container with those games. Neither CoD nor Simcity are heavy on the system requirements, they should both run very smooth with wine.

Thing is, with linux you just can't go wrong. Microsoft is the third largest linux support ticket seller on the face of the planet, even though they don't have any linux-staff, they just resell Novell SLES support tickets to their customers with a 50% price premium. In fact, you might say that Microsoft finances SLES, per year they sell about 300 million dollars worth of support tickets for Novell. In return, Microsoft asks of Novell that they accept that the fact that linux is FAT/NTFS compatible, means that linux is licensed from Microsoft, which is of course pure bullshit, but with mega-stupid and corrupt judges like the Apple-judge Koh and mega-dumb and corrupt civil servants like that Microsoft-woman that is in charge of Obama's anti-trust policy, Microsoft has a very good chance to pull it off anyways, look at the 2 billion dollars of license fees Microsoft receives from Android phone manufacturers for the use of the FAT filesystem, which they need to use, not for any technical reason, but simply because the US government forces them to use it, so that they can incorporate DRM, which makes use of Flash and Microsoft filesystems, both of which are archaic and extremely broken and unsafe technologies, and for that, 10-20 % of the manufacturing price of a phone goes to Microsoft... so the further you stay away from Microsoft and affiliates, and keep your system clean of open source, the more you benefit on all fronts. Sometimes that means sacrificing some user pseudo-comfort, like having to jump through some hoops to get games to work, but it's not like every game works out of the box on a MS-malware system, and often making "Made for Windows" games work on Windows is harder than making those games work on linux...

I can only give one advice to anyone that is serious about computing: talk to people, go on open source fora, post questions, send messages to devs or FOSS-support people, don't be afraid, the FOSS community is not XBox Live, 4Chan, YouTube or Google+, you won't be flamed for nothing. Learn linux by social interaction, linux and open source was and still is community developed thanks to the internet, without the communication channels provided by the internet, it simply would never have existed. So if you want to run a game in wine bout don't know how, hit winehq on the net and ask around. I'm not the biggest gaming specialist, I'm not the biggest gamer, and IF I play games, that's mostly FOSS games that are linux-native or pure cross-platform, so I can't give many specific hints on making specific windows-games work on linux with wine on specific hardware combinations, I don't even have wine installed on most of my systems. But the guys at winehq, crossover and winetricks know everything there is to know and can probably give you the best configuration for your games on your system.

I do understand that MS is a rather bad company I personally think it has become worse since bills departure, and I hope the new CEO will push MS in the correct direction although I am not holding my breath, and thanks for the direction, I hear that Manjaro IRC is a very friendly place to be, if only people cared about their privacy as much as others.

Thanks for the advice I will put it into practice :)

Thanks a lot. I've been wanting to do this for a long, long time.

Now, I have a slightly different question: would I be able to run a Debian host + Windows 7 Guest + Ubuntu guest system on an i5-3570K and with 8GB RAM and still play games with about native Windows performance?
(Yes I have the requisite amount of graphics cards and monitors -> onboard for host, HD7950 for Win7, HD6670 2GB for Ubuntu. My question is if it will run well?)

As far as I know no. because of your CPU locking VT-d it is not possible for direct passthrough, There maybe a work around but I personally do not know.

The specs are fine you wont see many performance drops if any, just the fact you have a K series.

Xen is Free Software, GPL. You don't have to buy it to use it. Plus, Xen has XenGT, a feature that can bypass all the virtual drivers and virtual software involved and give your game direct access to the graphics hardware. XenGT also allows for hybrid access, so you can conceivably do things, under certain conditions, like running nvidia only games on ATI hardware or games that only run on add-in cards can be virtually run using onboard cards. As of today, _no_other_virtualizaters_do_anything_like_XenGT_ but all GPL compatible projects are certainly going to add XenGT (its GPL, they can). QEMU has already started working on it. And, proprietary virtualization will never have XenGT so long as they remain proprietary (this doesn't stop them from creating their own 3D solutions at some future date). I'm not recommending Xen per se, just providing information.

Hmm thanks for that, sounds like an easy pass through :) I have open source drivers enabled also, forever moving to full FOSS :D