Design and Analysis of Almost-Always-Sleeping Schedulers for Embedded Systems

Limited energy resources dictate the design of many embedded applications composed of small, modular tasks, scheduled periodically. In this model, the embedded device wakes, executes a task-set, and returns to sleep. These systems spend most of their time in a state of deep sleep to minimize power consumption. We refer to these systems as almost-always-sleeping (AAS) systems. In this paper, we describe a series of task schedulers for AAS systems designed to maximize sleep time. We consider four scheduler designs, model their performance, and present detailed performance analysis results under varying load conditions. This is the first systematic analysis of this important class of schedulers.