Distributed Shared Virtual File System

The shared virtual memory provides a virtual address space that is shared among all processors in a loosely coupled distributed-memory multiprocessor system. Application programs can us they do a traditional virtual memory, except, of course, that processes can run on different processors in parallel. The shared virtual memory not only “pages” data between physical memories and disks, as in a convention memory system, but it also “pages” data between the physical memories of the individual processors. The main difficulty in building a shared virtual memory is solving the memory coherence problem A prototype system called IVY has been implemented on a local area network of Apollo workstations. The experimental results of nontrivial parallel programs run on the prototype show the viability of a shared virtual memory. The success of this implementation suggests an operating mode for such total processing power and memory capabilities in a far more unified way than the traditional “messagepassing” approach.