1. A computer-implemented method in a server computing system for dynamically allocating physical graphics processing unit (GPU) resources among a plurality of virtual machines to be potentially allocated some portion of the physical GPU resources, the physical GPU resources including processing bandwidth of at least one physical GPU available to the server computing system, comprising: determining a processing capacity of each physical GPU resource; determining a GPU benefit factor for each virtual machine of the plurality of virtual machines, the GPU benefit factor being a numerical value indicating benefit to the virtual machine of using a GPU resource, wherein a larger GPU benefit factor indicates a greater benefit; receiving a priority for each of the plurality of virtual machines; ranking the plurality of virtual machines based on the GPU benefit factor and the priority of each virtual machine, wherein virtual machines having the same priority are ranked based on the GPU benefit factor from largest to smallest; establishing an allocation of the physical GPU resources among the plurality of virtual machines by assigning each physical GPU resource to one or more of the plurality of virtual machines based upon the determined capacity of each physical GPU and the ranking of the plurality of virtual machines, wherein the physical GPU resources are assigned based on the ranking from highest to lowest; determining a revised GPU benefit factor for at least one of the plurality of virtual machines based upon runtime behavior of the at least one virtual machine; and dynamically adjusting the physical GPU resource allocation to account for the revised GPU benefit factor determined for the at least one virtual machine.