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Abstract : |
Abstract. Massively parallel processors have begun using commodity operating systems that support demand-paged virtual memory. To evaluate the utility of virtual memory, we measured the behavior of seven shared-memory parallel application programs on a simulated distributedshared-memory machine. Our results (1) confirm the importance of gang CPU scheduling, (2) show that a page-faulting processor should spin rather than invoke a parallel context switch, (3) show that our parallel programs frequently touch most of their data, and (4) indicate that memory, not just CPUs, must be "gang scheduled. " Overall, our experiments demonstrate that demand paging has limited value on current parallel machines because of the applications ' synchronization and memory reference patterns and the machines ' high page-fault and parallel context-switch overheads. Keywords: Shared-memory multiprocessors, virtual memory, scheduling, synchronization, |
