In a virtualized environment, physical resources are shared among multiple virtual machines.

Some virtualization processes dynamically allocate available resources depending on the status, or utilization rates, of virtual machines in the environment. This can make obtaining accurate information about the resource utilization (CPU utilization, in particular) of individual virtual machines, or applications running within virtual machines, difficult. VMware now provides virtual machine-specific performance counter libraries for the Windows Perfmon utility. Application administrators can view accurate virtual machine resource utilization statistics from within the guest operating system's Windows Perfmon utility.