Online Scheduling on Identical Machines using SRPT

Due to its optimality on a single machine for the problem of minimizing average flow time, ShortestRemaining-Processing-Time (SRPT) appears to be the most natural algorithm to consider for the problem of minimizing average flow time on multiple identical machines. It is known that SRPT achieves the best possible competitive ratio on multiple machines up to a constant factor. Using resource augmentation, SRPT is known to achieve total flow time at most that of the optimal solution when given machines of speed 2 - 1 m . Further, it is known that SRPT's competitive ratio improves as the speed increases; SRPT is s-speed 1 s -competitive when s 2 - 1 m . However, a gap has persisted in our understanding of SRPT. Before this work, the performance of SRPT was not known when SRPT is given (1 + )-speed when 0 < < 1 - 1 m , even though it has been thought that SRPT is (1 + )-speed O(1)-competitive for over a decade. Resolving this question was suggested in Open Problem 2.9 from the ...

• Type: Journal
• Year: 2010
• Where: CORR
• Authors: Kyle Fox, Benjamin Moseley
• Keywords: CORR 2010, Education, Flow Time, Machines, SRPT