Completion Time Scheduling and the WSRPT Algorithm

  • Bo Xiong
  • Christine Chung
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7422)


We consider the online scheduling problem of minimizing the total weighted and unweighted completion time on identical parallel machines with preemptible jobs. We show a new general lower bound of 21/19 ≈ 1.105 on the competitive ratio of any deterministic online algorithm for the unweighted problem and \(\frac{16-\sqrt{14}}{11} \approx 1.114\) for the weighted problem. We then analyze the performance of the natural online algorithm WSRPT (Weighted Shortest Remaining Processing Time). We show that WSRPT is 2-competitive. We also prove that the lower bound on the competitive ratio of WSRPT for this problem is 1.215.


Completion Time Parallel Machine Competitive Ratio Online Algorithm Deterministic Algorithm 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Bo Xiong
    • 1
  • Christine Chung
    • 1
  1. 1.Department of Computer ScienceConnecticut CollegeNew LondonUSA

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