J Supercomput DOI 10.1007/s11227-014-1305-8 Energy-efficient adaptive networked datacenters for the QoS support of real-time applications Nicola Cordeschi · Mohammad Shojafar · Danilo Amendola · Enzo Baccarelli © Springer Science+Business Media New York 2014 Abstract In this paper, we develop the optimal minimum-energy scheduler for the adaptive joint allocation of the task sizes, computing rates, communication rates and communication powers in virtualized networked data centers (VNetDCs) that oper- ate under hard per-job delay-constraints. The considered VNetDC platform works at the Middleware layer of the underlying protocol stack. It aims at supporting real-time stream service (such as, for example, the emerging big data stream computing (BDSC) services) by adopting the software-as-a-service (SaaS) computing model. Our objec- tive is the minimization of the overall computing-plus-communication energy con- sumption. The main new contributions of the paper are the following ones: (i) the computing-plus-communication resources are jointly allotted in an adaptive fashion by accounting in real-time for both the (possibly, unpredictable) time fluctuations of the offered workload and the reconfiguration costs of the considered VNetDC platform; (ii) hard per-job delay-constraints on the overall allowed computing-plus- communication latencies are enforced; and, (iii) to deal with the inherently nonconvex nature of the resulting resource optimization problem, a novel solving approach is developed, that leads to the lossless decomposition of the afforded problem into the cascade of two simpler sub-problems. The sensitivity of the energy consumption of N. Cordeschi · M. Shojafar · D. Amendola · E. Baccarelli (B ) Department of Information, Electrical and Telecommunication (DIET) engineering, “Sapienza” University of Rome, Via Eudossiana 18, 00184 Rome, Italy e-mail: enzo.baccarelli@uniroma1.it N. Cordeschi e-mail: nicola.cordeschi@diet.uniroma1.it M. Shojafar e-mail: shojafar@diet.uniroma1.it D. Amendola e-mail: amendola@diet.uniroma1.it 123