Online deadline scheduling: multiple machines and randomization

  • Authors:
  • Jae-Ha Lee

  • Affiliations:
  • Konkuk University, Korea

  • Venue:
  • Proceedings of the fifteenth annual ACM symposium on Parallel algorithms and architectures
  • Year:
  • 2003

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Abstract

We study the competitiveness of online deadline scheduling problems. It is assumed that jobs are non-preemptive and we want to maximize, in an online manner, the sum of the length of jobs completed before their deadlines. When there is a single machine, Goldwasser [4] showed that the optimal deterministic competitiveness of this problem is 2+1/k, where each job of length L can be delayed for at least k • L before it is started, while still meeting its deadline. We consider the case that k O((log 1/k ))-competitive randomized algorithm not only for a single machine but also for m machines where m = 1,2,•••, O(( log 1/k )).Of particular interest is our technique: we mainly consider deterministic algorithms for multiple machines in order to improve the randomized competitiveness for a single (or more) machine. Though this approach is not completely new, it is rather complicated in our case to design a deterministic algorithm for multiple machines. Specifically, we present an [m+1+ m • (1/k)(1/m)]-competitive deterministic algorithm, where m (≥ 2) machines are available to both online algorithms and the adversary.Finally we also study a related problem and present an improved algorithm.