SHF: Small: Variability-Aware System-Level Power Management in Multi-Processor Systems

University Of Southern California, Los Angeles CA

Investigators

Abstract

With the increasing levels of variability in the characteristics of nanoscale CMOS devices and VLSI interconnects and continued uncertainty in the operating conditions of VLSI circuits, achieving power efficiency and high performance in electronic systems under process, voltage, and temperature variations as well as current stress, device aging, and interconnect wear-out phenomena has become a daunting, yet vital, task. This proposal tackles the problem of system-level dynamic power management (DPM) in systems which are manufactured in nanoscale CMOS technologies and are operated under widely varying conditions over the lifetime of the system. Such systems are greatly affected by increasing levels of process variations typically materializing as intrinsic (random) or systematic sources of variability and wearout/aging effects in device and interconnect characteristics, and widely varying workloads and temperature fluctuations usually appearing as sources of uncertainty. At the system level this variability and uncertainty is beginning to undermine the effectiveness of traditional DPM approaches. It is thus critically important that we develop the mathematical basis and practical applications of a variability-aware, uncertainty-reducing DPM approach with the following unique features and capabilities: Utilization of a two-tier stochastic modeling framework based on the theories of variability-sensitive, partially observable Markovian Decision Model and closed-loop feedback control theory, which can efficiently cope with variability and effectively reduce uncertainty in key system parameters. The framework also allows for self-learning (adaptive) policy optimization approaches, and multi-manager systems with multiple reward and cost rates for simultaneous optimization of the system energy consumption and performance. Successfully overcoming the challenges addressed by this project will result in significant energy savings for a typical server. Other impacts of this research includes the development of a new and powerful mathematical framework for resource management in complex and large systems that can deal with multiple-agents, multiple reward and cost rates and discount factors while accounting for effects of variability and simultaneously reducing the impact of uncertainty through measurements and sampling. The stochastic decision making framework with closed loop feedback control is also useful for solving a variety of other problems including dynamic thermal control, concurrent DPM and task scheduling in multi-core processor systems, consideration of total system?s energy efficiency, energy-efficient power delivery network design. If successful, the approach can result in a practical stochastic optimization framework for handling many important problems, ranging from energy efficiency improvement (and hence reduction in cost of operation) for electronics systems to data centers comprised of a large number of server/storage elements. Education, Outreach, and Training Programs include new curricula; recruiting under-represented students; research internship opportunities for undergraduates; and a Junior Scholars program for high school students.