Architectural Exploration of Large-Scale Hierarchical Chip Multiprocessors

The continuous scaling of nanoelectronics is increasing the complexity of chip multiprocessors (CMPs) and exacerbating the memory wall problem. As CMPs become more complex, the memory subsystem is organized into more hierarchical structures to better exploit locality. To efficiently discover promising architectures within the rapidly growing search space, exhaustive exploration is replaced with tools that implement intelligent search strategies. Moreover, faster analytical models are preferred to costly simulations for estimating the performance and power of CMP architectures. The memory traffic generated by CMP cores has a cyclic dependency with the latency of the memory subsystem, which critically affects the overall system performance. Based on this observation, a novel scalable analytical method is proposed to estimate the performance of highly parallel CMPs (hundreds or thousands of cores) with hierarchical interconnect networks. The method can use customizable probabilistic models and solves the cyclic dependencies between traffic and latency by using a fixed-point strategy. By using the analytical model as a performance and power estimator, an efficient metaheuristic-based search is proposed for the exploration of large design spaces. The proposed techniques are shown to be very accurate and a promising strategy when compared to the results obtained by simulation.