The dramatic spread of computing, at the scale of trillions of ubiquitous devices, is delivering on the pervasive penetration into the real world in the form of Internet of Things (IoT). Today, the widely used power-efficient paradigms directly related to the behaviour of computing systems are those of real-time (working to deadlines imposed from the real world) and low-power (prolonging battery life or reducing heat dissipation and electricity bills). None of these addresses the strict requirements on power supply, allocation and utilisation that are imposed by the needs of new devices and applications in the computing swarm - many of which are expected to be confronted with challenges of autonomy and battery-free long life. Indeed, we need to design and build systems for survival, operating under a wide range of power constraints; we need a new power-driven paradigm called real-power computing (RPC). The article provides an overview of this emerging paradigm with definition, taxonomies and a case study, together with a summary of the existing research. Towards the end, the overview leads to research and development challenges and opportunities surfacing this paradigm. Throughout the article, we have used the power and energy terms as follows. From the supply side, the energy term will be used to refer to harvesters with built-in storage, while the power term will indicate instantaneous energy dispensation. For the computing logic side, the energy term will define the total power consumed over a given time interval.

Chapter Contents:

• 11.1 Computing is evolving
• 11.2 Power-driven computing
• 11.2.1 Real-power computing
• 11.2.1.1 Hard real-power computing
• 11.2.1.2 Soft real-power computing
• 11.2.2 Performance constraints in power-driven systems
• 11.3 Design-time considerations
• 11.3.1 Power supply models and budgeting
• 11.3.2 Power-proportional systems design
• 11.3.2.1 Computation tasks
• 11.3.2.2 Communication tasks
• 11.3.3 Power scheduling and optimisation
• 11.4 Run-time considerations
• 11.4.1 Adapting to power variations
• 11.4.2 Dynamic retention
• 11.5 A case study of power-driven computing
• 11.6 Existing research
• 11.7 Research challenges and opportunities
• 11.7.1 Power-proportional many-core systems
• 11.7.2 Design flow and automation
• 11.7.3 On-chip sensing and controls
• 11.7.4 Software and programming model
• 11.8 Conclusion and future directions
• References

Inspec keywords: power consumption; energy harvesting; power aware computing

Other keywords: harvesters; power utilisation; ubiquitous devices; instantaneous energy dispensation; power supply; Internet of Things; power-driven computing; total power consumption; RPC; power allocation; built-in storage; real-power computing

Subjects: Operating systems; Performance evaluation and testing; Electrical/electronic equipment (energy utilisation)