On the limits of program parallelism and its smoothability

Abstract

There have been many recent studies of the “limits on instruction parallelism” an application programs. This paper reports a new study of instruction-level parallelism which examines aspects not covered in previous studies, including the effects of various memory reuse policies and long-latency operations, and the results achieved when large benchmarks are allowed to run to completion. We also define and study program smoothability, which quantifies the extent to which deferring program operations from periods of peak parallelism increases execution time. The results show a high degree of smoothability, suggesting that processor utilization can be quite high when the number of pro