Abstract
We revisit the classic problem of preemptive scheduling on m uniformly related machines. In this problem, jobs can be arbitrarily split into parts, under the constraint that every job is processed completely, and that the parts of a job are not assigned to run in parallel on different machines. We study a new objective which is motivated by fairness, where the goal is to minimize the sum of the two maximal job completion times. We design a polynomial time algorithm for computing an optimal solution. The algorithm can act on any set of machine speeds and any set of input jobs. The algorithm has several cases, many of which are very different from algorithms for makespan minimization (algorithms that minimize the maximum completion time of any job), and from algorithms that minimize the total completion time of all jobs.
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Notes
The number of parts for each job must be finite, and the parts must have positive sizes.
A short summary of the action of the algorithm of Ebenlendr and Sgall (2009) is as follows. It keeps an infinite number of machines that can be used during the time [0, T). The machines have time-dependent speeds. The actual machines are initialized with their actual speeds, while dummy machines are initialized with zero speeds. Each job is assigned to run during [0, T), possibly on several machines, with the convention that running on a machine of speed zero during some time means not running at all at that time. By assigning a job, two machines are merged into what will be seen as one machine (this merged machine usually will not have a constant speed).
The action of the function can be seen as solving a linear program, but since the program is simple, we solve it directly. We do not use this property (that a linear program is being solved) in the proof, and thus we do not describe the function as such.
References
Bruno, J. L., Coffman, E. G, Jr., & Sethi, R. (1974). Scheduling independent tasks to reduce mean finishing time. Communications of the ACM, 17(7), 382–387.
Bruno, J. L., & Gonzalez, T. (1976). Scheduling independent tasks with release dates and due dates on parallel machines. Technical Report 213, The Pennsylvania State University.
Ebenlendr, T., & Sgall, J. (2009). Optimal and online preemptive scheduling on uniformly related machines. Journal of Scheduling, 12(5), 517–527. (Also in STACS 2004).
Epstein, L., & Tassa, T. (2006). Optimal preemptive scheduling for general target functions. Journal of Computer and System Sciences, 72(1), 132–162.
Gonzales, T. F., & Sahni, S. (1978). Preemptive scheduling of uniform processor systems. Journal of the ACM, 25(1), 92–101.
Horn, W. A. (1973). Minimizing average flow time with parallel machines. Operations Research, 21(3), 846–847.
Horvath, E. C., Lam, S., & Sethi, R. (1977). A level algorithm for preemptive scheduling. Journal of the ACM, 24(1), 32–43.
Labetoulle, J., Lawler, E., Lenstra, J. K., & Rinnooy Kan, A. H. G. (1984). Preemptive scheduling of uniform machines subject to release dates. In W. R. Pulleyblank (Ed.), Progress in combinatorial optimization (pp. 245–261). Toronto, Canada: Academic Press.
Lawler, E. L., & Labetoulle, J. (1978). On preemptive scheduling of unrelated parallel processors by linear programming. Journal of the ACM, 25(4), 612–619.
Liu, J., & Yang, A. (1974). Optimal scheduling of independent tasks on heterogeneous computing systems. In Proceedings of the ACM national conference, vol. 1 (pp. 38–45). ACM
McNaughton, R. (1959). Scheduling with deadlines and loss functions. Management Science, 6(1), 1–12.
Shachnai, H., Tamir, T., & Woeginger, G. J. (2005). Minimizing makespan and preemption costs on a system of uniform machines. Algorithmica, 42(3–4), 309–334.
Sitters, R. (2001). Two NP-hardness results for preemptive minsum scheduling of unrelated parallel machines. In Proceedings of 8th international conference on integer programming and combinatorial optimization (IPCO2001) (pp. 396–405).
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Epstein, L., Yatsiv, I. Preemptive scheduling on uniformly related machines: minimizing the sum of the largest pair of job completion times. J Sched 20, 115–127 (2017). https://doi.org/10.1007/s10951-016-0476-y
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DOI: https://doi.org/10.1007/s10951-016-0476-y