A first-order superscalar processor model

A proposed performance model for superscalar processors consists of: 1) a component that models the relationship between instructions issued per cycle and the size of the instruction window under ideal conditions; and 2) methods for calculating transient performance penalties due to branch mispredictions, instruction cache misses, and data cache misses. Using trace-derived data dependence information, data and instruction cache miss rates, and branch miss-prediction rates as inputs, the model can arrive at performance estimates for a typical superscalar processor that are within 5.8% of detailed simulation on average and within 13% in the worst case. The model also provides insights into the workings of superscalar processors and long-term microarchitecture trends such as pipeline depths and issue widths.