Configurational Workload Characterization

Although the best processor design for executing a specific workload does depend on the characteristics of the workload, it can not be determined without factoring-in the effect of the interdependencies between different architectural subcomponents. Consequently, workload characteristics alone do not provide accurate indication of which workloads can perform close-to-optimal on the same architectural configuration. The primary goal of this paper is to demonstrate that, in the design of a heterogeneous CMP, reducing the set of essential benchmarks based on relative similarity in raw workload behavior may direct the design process towards options that result in sub-optimality of the ultimate design. It is shown that the design parameters of the customized processor configurations, what we refer to as the configurational characteristics, can yield a more accurate indication of the best way to partition the workload space for the cores of a heterogeneous system to be customized to. In order to automate the extraction of the configurational- characteristics of workloads, a design exploration tool based on the Simplescalar timing simulator and the CACTI modeling tool is presented. Results from this tool are used to display how a systematic methodology can be employed to determine the optimal set of core configurations for a heterogeneous CMP under different design objectives. In addition, it is shown that reducing the set of workloads based on even a single widely documented benchmark similarity (between bzip and gzip) can lead to a slowdown in the overall performance of a heterogeneous-CMP design.