VHM : a Virtual Hardware Monitor

We describe here the features and the implementation of a system that collects information about the activity of the virtual machines generated by CP-67. This system can collect information about CPU usage and I/O activity of the virtual machine without interfering with its operation and without knowing what the system running in the virtual machine is doing. In this sense it behaves like an hardware monitor behaves on a real machine, and hence has been called Virtual Hardware Monitor (VHM). VHM provides a general tool that can be used by any virtual machine. The information it provides, eventually used in connection with those provided by other systems that monitor the total activity of CP-67, can lead to a better knowledge of the load of CP-67 and to an improvement in the performance of CP-67 itself and in the performance of the various virtual machines.