Cross-component energy management

Abstract

Researchers have proposed the use of adaptation to reduce the energy consumption of different hardware components, such as the processor, memory, disk, and display for general-purpose applications. Previous algorithms to control these adaptations, however, have focused on a single component. This work takes the first step toward developing algorithms that can jointly control adaptations in multiple interacting components for general-purpose applications, with the goal of minimizing the total energy consumed within a specified performance loss. Specifically, we develop a joint-adaptation algorithm for processor and memory adaptations. We identify two properties that enable per-component algorithms to be easily used in a cross-component context---the algorithms' performance impact must be guaranteed and composable. We then modify a current processor and a memory algorithm to obey these properties. This allows the cross-component problem to be reduced to determine an appropriate (energy-optimal) allocation of the target performance loss (slack) between the two components. We develop such an optimal slack allocation algorithm that exploits the above properties. The result is an efficient cross-component adaptation framework that minimizes the total energy of the processor and memory without exceeding the target performance loss, while substantially leveraging current per-component algorithms. Our experiments show that joint processor and memory adaptation provides significantly more energy savings than adapting either component alone; intelligent slack distribution is specifically effective for highly compute- or memory-intensive applications; and the performance slowdown never exceeds the specification.