Analysis and approximation of optimal co-scheduling on chip multiprocessors

  • Authors:

  • Yunlian Jiang;Xipeng Shen;Jie Chen;Rahul Tripathi

  • Affiliations:

  • College of William and Mary, Williamsburg, VA, USA;College of William and Mary, Williamsburg, VA, USA;Thomas Jefferson National Accelerator Facility, Newport News, VA, USA;University of South Florida, Tampa, FL, USA

  • Venue:
  • Proceedings of the 17th international conference on Parallel architectures and compilation techniques
  • Year:
  • 2008

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Abstract

Cache sharing among processors is important for Chip Multiprocessors to reduce inter-thread latency, but also brings cache contention, degrading program performance considerably. Recent studies have shown that job co-scheduling can effectively alleviate the contention, but it remains an open question how to efficiently find optimal co-schedules. Solving the question is critical for determining the potential of a co-scheduling system. This paper presents a theoretical analysis of the complexity of co-scheduling, proving its NP-completeness. Furthermore, for a special case when there are two sharers per chip, we propose an algorithm that finds the optimal co-schedules in polynomial time. For more complex cases, we design and evaluate a sequence of approximation algorithms, among which, the hierarchical matching algorithm produces near-optimal schedules and shows good scalability. This study facilitates the evaluation of co-scheduling systems, as well as offers some techniques directly usable in proactive job co-scheduling.