Thermal-Aware Scheduling for Future Chip Multiprocessors

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Research Article Thermal-Aware Scheduling for Future Chip Multiprocessors Kyriakos Stavrou and Pedro Trancoso Department of Computer Science, University of Cyprus, 75 Kallipoleos Street, P.O. Box 20537, 1678 Nicosia, Cyprus Received 10 July 2006; Revised 12 December 2006; Accepted 29 January 2007 Recommended by Antonio Nunez The increased complexity and operating frequency in current single chip microprocessors is resulting in a decrease in the performance improvements. Consequently, major manufacturers offer chip multiprocessor (CMP) architectures in order to keep up with the expected performance gains. This architecture is successfully being introduced in many markets including that of the embedded systems. Nevertheless, the integration of several cores onto the same chip may lead to increased heat dissipation and consequently additional costs for cooling, higher power consumption, decrease of the reliability, and thermal-induced performance loss, among others. In this paper, we analyze the evolution of the thermal issues for the future chip multiprocessor architectures and show that as the number of on-chip cores increases, the thermal-induced problems will worsen. In addition, we present several scenarios that result in excessive thermal stress to the CMP chip or significant performance loss. In order to minimize or even eliminate these problems, we propose thermal-aware scheduler (TAS) algorithms. When assigning processes to cores, TAS takes their temperature and cooling ability into account in order to avoid thermal stress and at the same time improve the performance. Experimental results have shown that a TAS algorithm that considers also the temperatures of neighboring cores is able to significantly reduce the temperature-induced performance loss while at the same time, decrease the chip’s temperature across many different operation and configuration scenarios. Copyright © 2007 K. Stavrou and P. Trancoso. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

1.

INTRODUCTION

The doubling of microprocessor performance every 18 months has been the result of two factors: more transistors per chip and superlinear scaling of the processor clock with technology generation [1]. However, technology scaling together with frequency and complexity increase result in a significant increase of the power density. This trend, which is becoming a key-limiting factor to the performance of current state-of-the-art microprocessors [2–5], is likely to continue in future generations as well [4, 6]. The higher power density leads to increased heat dissipation and consequently higher operating temperature [7, 8]. To handle higher operating temperatures, chip manufactures have been using more efficient and more expensive cooling solutions [6, 9]. While such solutions were adequate in the past, these packages are now becoming prohibitively expensive, as the relationship betwe