A green policy to schedule tasks in a distributed cloud

In the last years, demand and availability of computational capabilities experienced radical changes. Desktops and laptops increased their processing resources, exceeding users’ demand for large part of the day. On the other hand, computational methods are more and more frequently adopted by scientific communities, which often experience difficulties in obtaining access to the required resources. Consequently, data centers for outsourcing use, relying on the cloud computing paradigm, are proliferating. Notwithstanding the effort to build energy-efficient data centers, their energy footprint is still considerable, since cooling a large number of machines situated in the same room or container requires a significant amount of power. The volunteer cloud, exploiting the users’ willingness to share a quote of their underused machine resources, can constitute an effective solution to have the required computational resources when needed. In this paper, we foster the adoption of the volunteer cloud computing as a green (i.e., energy efficient) solution even able to outperform existing data centers in specific tasks. To manage the complexity of such a large scale heterogeneous system, we propose a distributed optimization policy to task scheduling with the aim of reducing the overall energy consumption executing a given workload. To this end, we consider an integer programming problem relying on the Alternating Direction Method of Multipliers (ADMM) for its solution. Our approach is compared with a centralized one and other non-green targeting solutions. Results show that the distributed solution found by the ADMM constitutes a good suboptimal solution, worth to be applied in a real environment.