An instruction throughput model of superscalar processors

Abstract

With advances in semiconductor technology, processors are becoming larger and more complex. Future processor designers will face an enormous design space, and must evaluate more architecture design points to reach a final optimum design. This exploration is currently performed using cycle accurate simulators that are accurate but slow, limiting a comprehensive search of design options. The vast design space and time to market economic pressures motivate the need for faster architectural evaluation methods. The model presented in this paper facilitates a rapid exploration of the architecture design space for superscalar processors. It supplements current design tools by narrowing a large design space quickly, after which existing cycle accurate simulators can arrive at a precise optimum design. This allows the designer to select the final architecture design much faster than with traditional tools. The model calculates the instruction throughput of superscalar processors using a set of key architecture and application properties. It was validated with a Simplescalar out-of-order simulator. Results were within 5.5% accuracy of the cycle accurate simulator, but executed 40,000 times faster.