Abstract
We give a polynomial time algorithm to compute an optimal energy and fractional weighted flow trade-off schedule for a speed-scalable processor with discrete speeds. Our algorithm uses a geometric approach that is based on structural properties obtained from a primal–dual formulation of the problem.
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Notes
A non-trivial schedule is one that never runs at speed 0 when there is work remaining.
For the finite number of preemptions, note that any schedule can be transformed to a highest density first (HDF) schedule (see also next paragraph), in which the number of preemptions is bounded by the number of release times. For the finite number of speed switches, consider the average speed s in any maximal execution interval of some job j (where it runs at possible different speeds). If s lies between discrete speeds \(s_i\) and \(s_{i+1}\), the schedule can be changed to run first for some time at speed \(s_{i+1}\) and then for some time at speed \(s_i\) without increasing the energy cost or the flow time.
Given any non-HDF schedule, one can swap two (arbitrarily small) portions of jobs that violate HDF. By definition of the cost function, this results in a strictly better schedule.
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Acknowledgments
The different authors (and thereby this work) were supported by: A fellowship within the Postdoc-Programme of the German Academic Exchange Service (A. Antoniadis); the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1247842 (N. Barcelo); the NSF Graduate Research Fellowship DGE-1038321 (M. Consuegra); the German Research Foundation (DFG) within the Collaborative Research Center On-The-Fly Computing (SFB 901) and by the Graduate School on Applied Network Science (P. Kling); by NSF Grants CCF-1115575, CNS-1253218, CCF-1421508, and an IBM Faculty Award (K. Pruhs); by a fellowship of Fondazione Ing. Aldo Gini, University of Padova, Italy (M. Scquizzato).
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A preliminary version of this work appeared in the Proceedings of the 31st Symposium on Theoretical Aspects of Computer Science (STACS), 2014 (see [4]).
M. Consuegra: Work done while at Florida International University.
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Antoniadis, A., Barcelo, N., Consuegra, M. et al. Efficient Computation of Optimal Energy and Fractional Weighted Flow Trade-Off Schedules. Algorithmica 79, 568–597 (2017). https://doi.org/10.1007/s00453-016-0208-x
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DOI: https://doi.org/10.1007/s00453-016-0208-x