On energy-optimal voltage scheduling for fixed-priority hard real-time systems

  • Authors:

  • Han-Saem Yun;Jihong Kim

  • Affiliations:

  • Seoul National University, Seoul, Korea;Seoul National University, Seoul, Korea

  • Venue:
  • ACM Transactions on Embedded Computing Systems (TECS)
  • Year:
  • 2003

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Abstract

We address the problem of energy-optimal voltage scheduling for fixed-priority hard real-time systems, on which we present a complete treatment both theoretically and practically. Although most practical real-time systems are based on fixed-priority scheduling, there have been few research results known on the energy-optimal fixed-priority scheduling problem. First, we prove that the problem is NP-hard. Then, we present a fully polynomial time approximation scheme (FPTAS) for the problem. For any ϵ 0, the proposed approximation scheme computes a voltage schedule whose energy consumption is at most (1 + ϵ) times that of the optimal voltage schedule. Furthermore, the running time of the proposed approximation scheme is bounded by a polynomial function of the number of input jobs and 1/ϵ. Given the NP-hardness of the problem, the proposed approximation scheme is practically the best solution because it can compute a near-optimal voltage schedule (i.e., provably arbitrarily close to the optimal schedule) in polynomial time. Experimental results show that the approximation scheme finds more efficient (almost optimal) voltage schedules faster than the best existing heuristic.