Hyper-V Program Manager
Yesterday I started talking about how Hyper-V schedules virtual processors – and spent most of my time talking about the virtual machine reserve. Today I would like to continue the discussion – but to now focus on the virtual machine limit.
Virtual machine limit
This is the second resource control setting that you can configure on the processor settings for a virtual machine and, like the virtual machine reserve, it is configured as a percentage of the total possible CPU usage of a virtual machine.
The virtual machine limit (or CPU limit) simply states that a virtual machine will never be allowed to use more than the specified percentage of its virtual processors – and compared to the other controls it is relatively easy to understand.
How do people use the CPU limit?
There is really only one common usage for the CPU limit – and that is for dealing with poorly written applications.
The classic scenario here is that you have a flaky application that is key to your operating environment – but every now and then it just gets confused and starts chewing up all the CPU resource it can. In these cases – you can use the CPU limit to make sure that it does not run away with all of your system resources.
What are the common problems involved in using a CPU limit?
There are two common problems that people deal with on the CPU limit:
Tomorrow I will continue looking at Hyper-V CPU scheduling by looking at “virtual machine weight”.