Improving energy efficiency of asymmetric chip multithreaded multiprocessors through reduced OS noise scheduling

The performance of the emerging chip multithreaded symmetric multiprocessors (SMPs) is of great importance to the high performance computing community. However, the growing power consumption of such systems is of increasing concern, and techniques that can be used to increase overall system power efficiency while sustaining performance are very desirable. Operating system (OS) noise can have a dramatic effect on system performance. Effectively handling the smaller operating system tasks while simultaneously preserving application thread synchronicity leads to gains in overall system efficiency. Recently, under a fixed power budget, asymmetric multiprocessors (AMP) have been proposed to improve the performance of multithreaded applications. An AMP in this context is a multiprocessor system in which its processors are not operating at the same frequency. This paper proposes two simple scheduling methods that reduce the impact of OS noise, while simultaneously taking advantage of an opportunity to increase overall machine energy efficiency on AMP servers. Prototyping AMPs on a commercial 2-way dual-core Hyper-Threaded (HT) Intel Xeon SMP server, using real power measurements across six SPEC OpenMP applications, indicate that the first proposed scheduler performs better on average for HT-enabled systems, while the second scheduler is superior on average for HT-disabled systems. Keyword: Asymmetric Multiprocessors, OS Noise, Scheduling, Energy Efficiency, OpenMP 1 Corresponding Author Tel.: (613) 533-3068 FAX: (613) 533-6615