Exploring the use of I/O Nodes for Computation in a MIMD Multiprocessor

As parallel systems move into the production scientific-computing world, the emphasis will be on cost-effective solutions that provide high throughput for a mix of applications. Costeffective solutions demand that a system make effective use of all of its resources. Many MIMD multiprocessors today, however, distinguish between "compute" and "I/O" nodes, the latter having attached disks and being dedicated to running the file-system server. This static division of responsibilities simplifies system management but does not necessarily lead to the best performance in workloads that need a different balance of computation and I/O. Of course, computational processes sharing a node with a file-system service may receive less CPU time, network bandwidth, and memory bandwidth than they would on a computationonly node. In this paper we begin to examine this issue experimentally. We found that highperformance I/O does not necessarily require substantial CPU time, leaving plenty of time for appli..