Software partitioned multi-processor system with flexible resource sharing levels

Multiple instances of operating systems execute cooperatively in a single multiprocessor computer wherein all processors and resources are electrically connected together. The single physical machine with multiple physical processors and resources is subdivided by software into multiple partitions, each running a distinct copy, or instance, of an operating system. Each of the partitions has access to its own physical resources plus resources designated as shared. The partitioning is performed by assigning all resources with a configuration tree. None, some, or all, resources may be designated as shared among multiple partitions. Each individual operating instance will generally be assigned the resources it needs to execute independently and these resources will be designated as "private." Other resources, particularly memory, can be assigned to more than one instance and shared. Shared memory is cache coherent so that instances may be tightly coupled, and may share resources that are normally allocated to a single instance. This allows previously distributed user or operating system applications which usually must pass messages via an external interconnect to operate cooperatively in the shared memory without the need for either an external interconnect or message passing. Examples of application that could take advantage of this capability include distributed lock managers and cluster interconnects. Newly-added resources, such as CPUs and memory, can be dynamically assigned to different partitions and used by instances of operating systems running within the machine by modifying the configuration.