A Survey of Techniques For Improving Energy Efficiency in Embedded Computing Systems

Recent technological advances have greatly improved the performance and features of embedded systems. With the number of just mobile devices now reaching nearly equal to the population of earth, embedded systems have truly become ubiquitous. These trends, however, have also made the task of managing their power consumption extremely challenging. In recent years, several techniques have been proposed to address this issue. In this paper, we survey the techniques for managing power consumption of embedded systems. We discuss the need of power management and provide a classification of the techniques on several important parameters to highlight their similarities and differences. This paper is intended to help the researchers and application-developers in gaining insights into the working of power management techniques and designing even more efficient high-performance embedded systems of tomorrow

The Design of a System Architecture for Mobile Multimedia Computers

This chapter discusses the system architecture of a portable computer, called Mobile Digital Companion, which provides support for handling multimedia applications energy efficiently. Because battery life is limited and battery weight is an important factor for the size and the weight of the Mobile Digital Companion, energy management plays a crucial role in the architecture. As the Companion must remain usable in a variety of environments, it has to be flexible and adaptable to various operating conditions. The Mobile Digital Companion has an unconventional architecture that saves energy by using system decomposition at different levels of the architecture and exploits locality of reference with dedicated, optimised modules. The approach is based on dedicated functionality and the extensive use of energy reduction techniques at all levels of system design. The system has an architecture with a general-purpose processor accompanied by a set of heterogeneous autonomous programmable modules, each providing an energy efficient implementation of dedicated tasks. A reconfigurable internal communication network switch exploits locality of reference and eliminates wasteful data copies

Multiprocessor design for real-time embedded systems

Multiprocessor design for real-time embedded system

Synthesis of application specific processor architectures for ultra-low energy consumption

In this paper we suggest that further energy savings can be achieved by a new approach to synthesis of embedded processor cores, where the architecture is tailored to the algorithms that the core executes. In the context of embedded processor synthesis, both single-core and many-core, the types of algorithms and demands on the execution efficiency are usually known at the chip design time. This knowledge can be utilised at the design stage to synthesise architectures optimised for energy consumption. Firstly, we present an overview of both traditional energy saving techniques and new developments in architectural approaches to energy-efficient processing. Secondly, we propose a picoMIPS architecture that serves as an architectural template for energy-efficient synthesis. As a case study, we show how the picoMIPS architecture can be tailored to an energy efficient execution of the DCT algorithm

VLSI architecture design approaches for real-time video processing

This paper discusses the programmable and dedicated approaches for real-time video processing applications. Various VLSI architecture including the design examples of both approaches are reviewed. Finally, discussions of several practical designs in real-time video processing applications are then considered in VLSI architectures to provide significant guidelines to VLSI designers for any further real-time video processing design works

GraphStep: A System Architecture for Sparse-Graph Algorithms

Many important applications are organized around long-lived, irregular sparse graphs (e.g., data and knowledge bases, CAD optimization, numerical problems, simulations). The graph structures are large, and the applications need regular access to a large, data-dependent portion of the graph for each operation (e.g., the algorithm may need to walk the graph, visiting all nodes, or propagate changes through many nodes in the graph). On conventional microprocessors, the graph structures exceed on-chip cache capacities, making main-memory bandwidth and latency the key performance limiters. To avoid this “memory wall,” we introduce a concurrent system architecture for sparse graph algorithms that places graph nodes in small distributed memories paired with specialized graph processing nodes interconnected by a lightweight network. This gives us a scalable way to map these applications so that they can exploit the high-bandwidth and low-latency capabilities of embedded memories (e.g., FPGA Block RAMs). On typical spreading activation queries on the ConceptNet Knowledge Base, a sample application, this translates into an order of magnitude speedup per FPGA compared to a state-of-the-art Pentium processor

Just In Time Assembly (JITA) - A Run Time Interpretation Approach for Achieving Productivity of Creating Custom Accelerators in FPGAs

The reconfigurable computing community has yet to be successful in allowing programmers to access FPGAs through traditional software development flows. Existing barriers that prevent programmers from using FPGAs include: 1) knowledge of hardware programming models, 2) the need to work within the vendor specific CAD tools and hardware synthesis. This thesis presents a series of published papers that explore different aspects of a new approach being developed to remove the barriers and enable programmers to compile accelerators on next generation reconfigurable manycore architectures. The approach is entitled Just In Time Assembly (JITA) of hardware accelerators. The approach has been defined to allow hardware accelerators to be built and run through software compilation and run time interpretation outside of CAD tools and without requiring each new accelerator to be synthesized. The approach advocates the use of libraries of pre-synthesized components that can be referenced through symbolic links in a similar fashion to dynamically linked software libraries. Synthesis still must occur but is moved out of the application programmers software flow and into the initial coding process that occurs when programming patterns that define a Domain Specific Language (DSL) are first coded. Programmers see no difference between creating software or hardware functionality when using the DSL. A new run time interpreter is introduced to assemble the individual pre-synthesized hardware accelerators that comprise the accelerator functionality within a configurable tile array of partially reconfigurable slots at run time. Quantitative results are presented that compares utilization, performance, and productivity of the approach to what would be achieved by full custom accelerators created through traditional CAD flows using hardware programming models and passing through synthesis