Energy Efficient Scheduling via Partial Shutdown

Motivated by issues of saving energy in data centers we define a collection of new problems referred to as "machine activation" problems. The central framework we introduce considers a collection of $m$ machines (unrelated or related) with each machine $i$ having an {\em activation cost} of $a_i$. There is also a collection of $n$ jobs that need to be performed, and $p_{i,j}$ is the processing time of job $j$ on machine $i$. We assume that there is an activation cost budget of $A$ -- we would like to {\em select} a subset $S$ of the machines to activate with total cost $a(S) \le A$ and {\em find} a schedule for the $n$ jobs on the machines in $S$ minimizing the makespan (or any other metric). For the general unrelated machine activation problem, our main results are that if there is a schedule with makespan $T$ and activation cost $A$ then we can obtain a schedule with makespan \makespanconstant T and activation cost \costconstant A, for any $\epsilon >0$. We also consider assignment costs for jobs as in the generalized assignment problem, and using our framework, provide algorithms that minimize the machine activation and the assignment cost simultaneously. In addition, we present a greedy algorithm which only works for the basic version and yields a makespan of $2T$ and an activation cost $A (1+\ln n)$. For the uniformly related parallel machine scheduling problem, we develop a polynomial time approximation scheme that outputs a schedule with the property that the activation cost of the subset of machines is at most $A$ and the makespan is at most $(1+\epsilon) T$ for any $\epsilon >0$

Development and testing of a networked PC power management tool

[Abstract]: One of the major themes of this project is Personal Computer (PC) power usage, which is a significant issue as many PCs run 24 hours per day and therefore potentially waste large amounts of power. This power wastage is unfortunate given that most operating systems support hibernation. As issues such as fossil fuels, carbon footprint, global warming etc., are highly topical and politicized, energy efficiency in electrical devices is a significant issue. Additionally, through capability developments such as ‘green’ computing, virtualization, and even edge computing, the Information and Communications Technology (ICT) industry is one of the few industries that seem to be taking ecological issues seriously. The main objectives of the project are: • The research and evaluation of a number statistics that relate to PC energy consumption. • Investigation of power spikes and network traffic floods which may be caused by simultaneous PC start-up. • Development of a software tool to control the start-up and shutdown of a PC either via scheduling or manual control. • Development of a software tool that remotely controls the start-up and shutdown of either singular or grouped PCs. In addition to the aim of reducing wasted power, this project aims to improve network traffic efficiency by minimizing network traffic congestion through controlling the sequence of PC start-up in a networked environment. This controlled start-up has a secondary benefit in potentially reducing the severity of power spikes due to a simultaneous PC start-up. It is hoped that further development and testing of the ‘PowerMan’ application will provide greater program functionality. Additionally, it is envisaged that this tool could be used in conjunction with more energy efficient PCs and peripherals and therefore provide an overall package that is power efficient whatever its state of operation, with little control or interaction from the user