Linked by Drumhellar on Thu 28th Jun 2012 11:18 UTC
Windows Since its introduction at Microsoft's BUILD conference last September, Windows 8 has garnered a large measure of attention, especially with regards to the new Metro interface. The feature that intrigued me the most, however, was the inclusion of Hyper-V.
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Performance on host system?
by ANorthernSoul on Thu 28th Jun 2012 16:55 UTC
ANorthernSoul
Member since:
2012-06-28

When Hyper-V is activated on 2008/R2 the host system becomes a client of the Hyper-V server. The experience is seamless to the user but the transition happens when it's activated. So my question is, how does this affect performance on the host system for things like games or other programs that rely on direct access to hardware? There is usually a performance degradation that happens when running software like games in virtual machines. Has Microsoft found a way around that on the host system?

Reply Score: 1

BluenoseJake Member since:
2005-08-11

There doesn't seem to be any performance penalty for the host, I run hyper-v on a AMD X2 2.4Ghz box with 8G of ram, running 2 Win2k8R2 vms, a 2k3r2 VM and a Debian VM, and can watch 1080p video, play games, whatever, while the box is streaming video to every other device in the house using tversity. It might be running ~50-60% cpu, but it's responsive and fast.

Reply Parent Score: 2

Drumhellar Member since:
2005-07-12

At least for Windows 8, Hyper-V is a service like any other (mostly), and doesn't virtualize the host like 2008/R2.
I've been playing Deus Ex lately, and haven't noticed a performance or quality difference with Hyper-V installed or not.

Edited 2012-06-28 18:50 UTC

Reply Parent Score: 2

tanzam75 Member since:
2011-05-19

At least for Windows 8, Hyper-V is a service like any other (mostly), and doesn't virtualize the host like 2008/R2.

I've been playing Deus Ex lately, and haven't noticed a performance or quality difference with Hyper-V installed or not.


You would not be able to feel the performance penalty in client usage. You would need to benchmark your machine before and after adding the Hyper-V role to get an accurate measurement.

Hyper-V is a hypervisor, or Type 1 virtual machine monitor. By definition, it runs directly on bare metal. This means that all OSes -- including the primary OS -- run on top of Hyper-V, rather than directly on the CPU.

The way it worked on Windows Server was that the primary Windows instance got direct access to the hardware, while the other virtual machines didn't. Thus, the primary Windows instance had access to sound and USB, even though it was running on top of Hyper-V, which did not provide emulated or enlightened devices for these functions.

Windows Server began running on top of Hyper-V as soon as the Hyper-V role was installed -- even if you created no other virtual machines. (This is why installing/removing Hyper-V required a reboot.)

Microsoft has stated that a CPU with SLAT will be required to run Hyper-V on Windows 8. This is presumably because high-performance video drivers will thrash the TLB if the CPU does not have SLAT. This may be acceptable on a server, but would be unacceptable on a workstation.

Reply Parent Score: 2