Thread scheduling for out-of-core applications with memory server on multicomputers

Abstract

Out-of-core applications perform poorly in paged virtual memory (VM) systems because demand paging involves slow disk I/O accesses. Much research has been done on reducing the I/O overhead in such applications by either reducing the number of I/Os or lowering the cost of each I/O operation. In this paper, we investigate a method that combines finegrained threading with a memory server model to improve the performance of out-of-core applications on multicomputers. The memory server model decreases the average cost of I/O operations by paging to remote memory, while the fine-grained thread scheduling reduces the number of I/O accesses by improving the data locality of applications. We have evaluated this method on an Intel Paragon with 7 applications. Our results show that the memory server system performs better than the VM disk paging by a factor of 5 for sequential applications and a factor of 1.5 to 2.2 for parallel applications. The fine-grained threading alone improves the VM disk paging performance by a factor of 10 and 1.2 to 3 respectively for sequential and parallel applications. Overall, the combination of these two techniques outperforms the VM disk paging by more than a factor of 12 for sequential applications and a factor of 3 to 6 for parallel applications.