Q. Can I modify the processor percentage allocations for Hyper-V virtual machines (VMs) while they’re running?

A. Yes. Although you can’t modify the amount of memory allocated to a VM while the VM is running, you can modify the amount of processor power reserved for a VM, the maximum power that a VM can use, and a VM’s weight in using processor power compared to other VMs running on the same server. While the VM is running, however, you can’t modify the number of cores allocated to a VM.

To change the available settings, use the Hardware options in the left pane of the VM’s settings menu in the Microsoft Management Console (MMC) Hyper-V Manager snap-in, as shown here. To access this screen, in the snap-in select the VM you want to modify, then select Settings.