Hyper-V R2 VM CPU Limits

[guest]

I have a Windows Server 2008 R2 box with the Hyper-V role. The machine has dual quad core Xeon X5500 chips. Since the X5500 series has hyper threading, this shows up as 16 cores.

Most of the time, I want the various VMs on the machine to share the server resources. Sometimes, however, I use this machine for performance testing CPU heavy applications. In those scenarios, I want to grant 90%+ of the machine's resource to a single VM.

As far as I can tell, that's not possible. Since Hyper-V only supports granting VM access to a max of 4 logical processors, the most I can ever give an individual VM is 25% of the total server resources. That's because the server thinks it has 16 cores, an 4/16 = 25%.

It seems to me that this is a huge limitation of Hyper-V. Is there a work around? Is there no way to use the full horsepower of the machine from inside a VM?

[guest]

That is true, all tho HyperV is still a fairly new product, people tend to forget that - looking at ESX server, which has had quite some time out there is running 8 cores per virtual machine as max. (a number that might be real or they could be holding back as MS still "only" have 4)


The calculation is always based on what workload your applications doing - If your application requires more than 4 cores you dont virtualize with HyperV - if your workload require more than 8 cores, you dont virtualize with VMware. (Obviously that is somewhat black/white stated, it doesnt change the fact that the virtualization road should always be considered and not blindly followed)


And yes it is indeed very limiting and it is a fact that most people overlook when virtualizing. Its all about expectations, expectations and expectations :)

[guest]

You can only allocate a maximum of 4 virtual CPUs to a VM. I am not aware of nor think there is any work around for adding addtional Virtual CPUs to a VM.

[guest]

That is true, all tho HyperV is still a fairly new product, people tend to forget that - looking at ESX server, which has had quite some time out there is running 8 cores per virtual machine as max. (a number that might be real or they could be holding back as MS still "only" have 4)


The calculation is always based on what workload your applications doing - If your application requires more than 4 cores you dont virtualize with HyperV - if your workload require more than 8 cores, you dont virtualize with VMware. (Obviously that is somewhat black/white stated, it doesnt change the fact that the virtualization road should always be considered and not blindly followed)


And yes it is indeed very limiting and it is a fact that most people overlook when virtualizing. Its all about expectations, expectations and expectations :)