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  1. X. Lu, S. Aalto and P. Lassila, Performance-Energy Trade-Off in Controllable Servers with Setup Delays, Australian Journal of Electrical and Electronics Engineering, vol. 13, no. 2, pp. 109-121, 2016 (link)(bib)
    Abstract: We develop simple queuing models for a single node in a server farm and analytically study the impact of setup delay on the performance-energy trade-off. The objective is to compare how an optimized static speed scaling scheme performs against two (gated and linear) optimized dynamic speed scaling schemes, where the processor can be switched off when it is idle but the penalty is the setup delay (time to wake up the processor from the off state and the energy consumed during the setup delay). In the gated scheme, the processor speed is zero when the server is idle and constant otherwise, and in the linear scheme the processing speed scales linearly with the number of jobs. We initially develop models under exponential assumptions and then generalize the models, whenever possible, for general distributions (both for the setup delay and the job sizes). Our results demonstrate that the setup delay has a considerable impact on the optimal trade-off. The linear scheme is always better than the gated scheme and, when the setup delays are long, even the static scheme can be better. Also, we observe that greater variability in the job size distribution leads to higher gains. In practice, the trade-off is affected highly by the parameters and our models allow an explicit evaluation of the trade-off.