Dynamically assigning cpus to different partitions each having an operation system instance in a shared memory space

Abstract

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 with the ability to run a distinct copy, or instance, of an operating system. At different times, different operating system instances may be loaded on a given partition. 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. The partitions themselves can also be changed without rebooting the system by modifying the configuration tree. CPUs, in particular, may be migrated, or reassigned, from one operating system instance to another, allowing different loads in the system to be accommodated. The migrations involve storing the processing context of a migrating processor prior to its reassignment and, after reassignment, loading any previous processing context that it may have stored from a previous execution with the partition to which it is reassigned. Hardware flags are also provided which include an identification of which CPU belongs to which partition, and an availability indicator for each CPU, which indicates whether a given CPU is available for SMP operation.