Virtual performance monitoring decoupled from hardware performance-monitoring units

A method for monitoring processor events within a virtualized computer system that includes one or more processors, one or more memories, one or more physical data-storage devices, and a virtualization layer that provides a virtual hardware interface to one or more virtual machines that each includes a guest operating system and one or more application programs that execute within an execution environment provided by the guest operating system, the method comprising:

• providing, as a component of the virtual hardware interface, a set of virtual performance monitoring registers that can be accessed by the one or more of the guest operating systems and that differ in one or more of number or and function from the hardware-level performance monitoring registers provided by any one of the one or more processors;
• and
• using the virtual performance monitoring registers to accumulate counts of events that can be interpreted by performance monitoring tools which display performance monitoring data and graphical representations to human users, the events selected from among events that include virtual events and hardware-level-monitored events;
• wherein the virtualization layer provides a virtual performance monitoring register that counts the occurrence of a specified type of virtual event over a monitoring time interval by:
• time multiplexing a hardware-level performance monitoring register in order to collect and accumulate counts of the occurrences of the specified type of virtual event from the hardware-level performance monitoring register during multiple time intervals each shorter than the monitoring time interval and that together represent a total accumulated time less than the monitoring time interval.

Computer instructions stored in a memory that, when executed by a physical processor, monitor processor events, within a virtualized computer system that includes one or more processors, one or more memories, one or more physical data-storage devices, and a virtualization layer that provides a virtual hardware interface to one or more virtual machines that each includes a guest operating system and one or more application programs that execute within an execution environment provided by the guest operating system, by:

• providing, as a component of the virtual hardware interface, a set of virtual performance monitoring registers that can be accessed by the one or more of the guest operating systems and differ in one or more of number m and function to from the hardware-level performance monitoring registers provided by any one of the one or more processors;
• and
• using the virtual performance monitoring registers to accumulate counts of events that can be interpreted by performance monitoring tools which display performance monitoring data and graphical representations to human users, the events selected from among events that include virtual events and hardware-level-monitored events;
• wherein the virtualization layer provides a virtual performance monitoring register that counts the occurrence of a specified type of virtual event over a monitoring time interval by:
• time multiplexing a hardware-level performance monitoring register in order to collect and accumulate counts of the occurrences of the specified type of virtual event from the hardware-level performance monitoring register during multiple time intervals each shorter than the monitoring time interval and that together represent a total accumulated time less than the monitoring time interval.