US Patent 7921261 Reserving a global address space

A method of operating a data processing system includes each of multiple tasks within a parallel job executing on multiple nodes of the data processing system issuing a respective system call to request reservation, without allocation of backing storage in physical memory, of a global address space defined by a range of effective addresses as global shared memory accessible to all of the multiple tasks within the parallel job. At least two of the tasks within the parallel job allocate global address spaces including a same effective address.