New Resource Augmentation Analysis of the Total Stretch of SRPT and SJF in Multiprocessor Scheduling

  • Wun-Tat Chan
  • Tak-Wah Lam
  • Kin-Shing Liu
  • Prudence W. H. Wong
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 3618)


This paper studies online job scheduling on multiprocessors and, in particular, investigates the algorithms SRPT and SJF for minimizing total stretch, where the stretch of a job is its flow time (response time) divided by its processing time. SRPT is perhaps the most well-studied algorithm for minimizing total flow time or stretch. This paper gives the first resource augmentation analysis of the total stretch of SRPT, showing that it is indeed O(1)-speed 1-competitive. This paper also gives a simple lower bound result that SRPT is not s-speed 1-competitive for any s < 1.5.

This paper also makes contribution to the analysis of SJF. Extending the work of [4], we are able to show that SJF is O(1)-speed 1-competitive for minimizing total stretch. More interestingly, we find that the competitiveness of SJF can be reduced arbitrarily by increasing the processor speed (precisely, SJF is O(s)-speed (1/s)-competitive for any s ≥ 1). We conjecture that SRPT also admits a similar result.


Processing Time Online Algorithm Single Processor Short Processing Time Online Schedule 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2005

Authors and Affiliations

  • Wun-Tat Chan
    • 1
  • Tak-Wah Lam
    • 1
  • Kin-Shing Liu
    • 1
  • Prudence W. H. Wong
    • 2
  1. 1.Department of Computer ScienceUniversity of Hong Kong 
  2. 2.Department of Computer ScienceUniversity of Liverpool 

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