Maintaining hardware resource bandwidth quality-of-service via hardware counter

A system comprising:

• a processor;
• a virtual machine (VM) to run on the processor;
• a hypervisor to manage the VM and to schedule the VM to run on the processor;
• a hardware resource;
• a bus connecting the processor to the hardware resource;
• a bandwidth counter associated with usage of the bus for the hardware resource and implemented directly in hardware as opposed to being a software-implemented counter;
• and
• a hardware component to adjust the bandwidth counter, without involvement of the VM or the hypervisor, each time the VM accesses the hardware resource over the bus when running on the processor, wherein the hardware resource and the hardware component are each hardware different than the processor.

A computer-readable data storage medium storing a computer program executable by a processor to implement a hypervisor, the processor further to run a first virtual machine (VM) and a second VM managed by the hypervisor and scheduled for running on the processor by the hypervisor, the computer program causing the hypervisor to perform a method comprising:

• responsive to an interrupt being issued by a hardware component responsive to a bandwidth counter associated with usage of a bus for a hardware resource reaching a threshold value and indicating that the first VM currently running on the processor has utilized a predetermined bandwidth allocation related to the hardware resource,
• switching the second VM for running on the processor instead of the first VM;
• and
• resetting the bandwidth counter to a predetermined value associated with the second VM,
• wherein the hardware resource and the hardware component are each hardware different than the processor,
• and wherein the bandwidth counter is implemented directly in hardware as opposed to being a software-implemented counter.