Identifying optimal multicore cache hierarchies for loop-based parallel programs via reuse distance analysis

Abstract

Understanding multicore memory behavior is crucial, but can be challenging due to the complex cache hierarchies employed in modern CPUs. In today's hierarchies, performance is determined by complicated thread interactions, such as interference in shared caches and replication and communication in private caches. Researchers normally perform extensive simulations to study these interactions, but this can be costly and not very insightful. An alternative is multicore reuse distance (RD) analysis, which can provide extremely rich information about multicore memory behavior. In this paper, we apply multicore RD analysis to better understand cache system design. We focus on loop-based parallel programs, an important class of programs for which RD analysis provides high accuracy. We propose a novel framework to identify optimal multicore cache hierarchies, and extract several new insights. We also characterize how the optimal cache hierarchies vary with core count and problem size.