Scheduling jobs before shut-down

  • Authors:
  • Vincenzo Liberatore

  • Affiliations:
  • Electrical Engineering and Computer Science Department Case Western Reserve University, 10900 Euclid Avenue Cleveland, Ohio

  • Venue:
  • Nordic Journal of Computing
  • Year:
  • 2000

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Abstract

Distributed systems execute background or alternative jobs while waiting for data or requests to arrive from another processor. In those cases, the following shut-down scheduling problem arises: given a set of jobs of known processing time. schedule them on m machines so as to maximize the total weight of jobs completed before an initially unknown deadline. We present optimally competitive deterministic and randomized algorithms for shut-down scheduling. Our deterministic algorithm is parameterized by the number m of machines. Its competitive ratio increases as the number of machines decreases, but it is optimal for any given choice of m. Such a family of deterministic algorithms can be translated into a family of randomized algorithms that use progressively less randomization and that are optimal for any given number of fair coin tosses. Hence, we establish a precise trade-off between the amount of randomization and the best possible competitive ratio.