The Impact of Performance Asymmetry in Emerging Multicore Architectures

Abstract

Performance asymmetry in multicore architectures arises when individual cores have different performance. Building such multicore processors is desirable because many simple cores together provide high parallel performance while a few complex cores ensure high serial performance. However, application developers typically assume computational cores provide equal performance, and performance asymmetry breaks this assumption. This paper is concerned with the behavior of commercial applications running on performance asymmetric systems. We present the first study investigating the impact of performance asymmetry on a wide range of commercial applications using a hardware prototype. We quantify the impact of asymmetry on an application's performance variance when run multiple times, and the impact on the application's scalability. Performance asymmetry adversely affects behavior of many workloads. We study ways to eliminate these effects. In addition to asymmetry-aware operating system kernels, the application often itself needs to be aware of performance asymmetry for stable and scalable performance.