We measure the performance and scalability of IBM's General Parallel File System (GPFS) under a variety of conditions. The measurements are based on benchmark programs that allow us to vary block sizes, access patterns, etc., and to measure aggregate throughput rates. We use the data to give performance recommendations for application development and as a guide to the improvement of parallel file systems.

The DI interpreter is both a debugger and interpreter of SISAL programs. Its use as a program interpreter is only a small part of its role; it is designed to be a tool for studying compilation techniques for applicative languages. DI interprets dataflow graphs expressed in the IF1 and IF2 languages, and is heavily instrumented to report the activity of dynamic storage activity, reference counting, copying and updating of structured data values. It also aids the SISAL language evaluation by providing an interim execution vehicle for SISAL programs. DI provides determinate, sequential interpretation of graph nodes for sequential and parallel operations in a canonical order. As a debugging aid, DI allows tracing, breakpointing, and interactive display of program data values. DI handles creation of SISAL and IF1 error values for each data type and propagates them according to a well-defined algebra. We have begun to implement IF1 optimizers and have measured the improvements with DI.