Low Power Processor Architectures and Contemporary Techniques for Power Optimization – A Review

The technological evolution has increased the number of transistors for a given die area significantly and increased the switching speed from few MHz to GHz range. Such inversely proportional decline in size and boost in performance consequently demands shrinking of supply voltage and effective power dissipation in chips with millions of transistors. This has triggered substantial amount of research in power reduction techniques into almost every aspect of the chip and particularly the processor cores contained in the chip. This paper presents an overview of techniques for achieving the power efficiency mainly at the processor core level but also visits related domains such as buses and memories. There are various processor parameters and features such as supply voltage, clock frequency, cache and pipelining which can be optimized to reduce the power consumption of the processor. This paper discusses various ways in which these parameters can be optimized. Also, emerging power efficient processor architectures are overviewed and research activities are discussed which should help reader identify how these factors in a processor contribute to power consumption. Some of these concepts have been already established whereas others are still active research areas. © 2009 ACADEMY PUBLISHER

A Many-Core Overlay for High-Performance Embedded Computing on FPGAs

In this work, we propose a configurable many-core overlay for high-performance embedded computing. The size of internal memory, supported operations and number of ports can be configured independently for each core of the overlay. The overlay was evaluated with matrix multiplication, LU decomposition and Fast-Fourier Transform (FFT) on a ZYNQ-7020 FPGA platform. The results show that using a system-level many-core overlay avoids complex hardware design and still provides good performance results.Comment: Presented at First International Workshop on FPGAs for Software Programmers (FSP 2014) (arXiv:1408.4423

Baseband analog front-end and digital back-end for reconfigurable multi-standard terminals

Multimedia applications are driving wireless network operators to add high-speed data services such as Edge (E-GPRS), WCDMA (UMTS) and WLAN (IEEE 802.11a,b,g) to the existing GSM network. This creates the need for multi-mode cellular handsets that support a wide range of communication standards, each with a different RF frequency, signal bandwidth, modulation scheme etc. This in turn generates several design challenges for the analog and digital building blocks of the physical layer. In addition to the above-mentioned protocols, mobile devices often include Bluetooth, GPS, FM-radio and TV services that can work concurrently with data and voice communication. Multi-mode, multi-band, and multi-standard mobile terminals must satisfy all these different requirements. Sharing and/or switching transceiver building blocks in these handsets is mandatory in order to extend battery life and/or reduce cost. Only adaptive circuits that are able to reconfigure themselves within the handover time can meet the design requirements of a single receiver or transmitter covering all the different standards while ensuring seamless inter-interoperability. This paper presents analog and digital base-band circuits that are able to support GSM (with Edge), WCDMA (UMTS), WLAN and Bluetooth using reconfigurable building blocks. The blocks can trade off power consumption for performance on the fly, depending on the standard to be supported and the required QoS (Quality of Service) leve

Interconnect architectures for dynamically partially reconfigurable systems

Dynamically partially reconfigurable FPGAs (Field-Programmable Gate Arrays) allow hardware modules to be placed and removed at runtime while other parts of the system keep working. With their potential benefits, they have been the topic of a great deal of research over the last decade. To exploit the partial reconfiguration capability of FPGAs, there is a need for efficient, dynamically adaptive communication infrastructure that automatically adapts as modules are added to and removed from the system. Many bus and network-on-chip (NoC) architectures have been proposed to exploit this capability on FPGA technology. However, few realizations have been reported in the public literature to demonstrate or compare their performance in real world applications. While partial reconfiguration can offer many benefits, it is still rarely exploited in practical applications. Few full realizations of partially reconfigurable systems in current FPGA technologies have been published. More application experiments are required to understand the benefits and limitations of implementing partially reconfigurable systems and to guide their further development. The motivation of this thesis is to fill this research gap by providing empirical evidence of the cost and benefits of different interconnect architectures. The results will provide a baseline for future research and will be directly useful for circuit designers who must make a well-reasoned choice between the alternatives. This thesis contains the results of experiments to compare different NoC and bus interconnect architectures for FPGA-based designs in general and dynamically partially reconfigurable systems. These two interconnect schemes are implemented and evaluated in terms of performance, area and power consumption using FFT (Fast Fourier Transform) andANN(Artificial Neural Network) systems as benchmarks. Conclusions drawn from these results include recommendations concerning the interconnect approach for different kinds of applications. It is found that a NoC provides much better performance than a single channel bus and similar performance to a multi-channel bus in both parallel and parallel-pipelined FFT systems. This suggests that a NoC is a better choice for systems with multiple simultaneous communications like the FFT. Bus-based interconnect achieves better performance and consume less area and power than NoCbased scheme for the fully-connected feed-forward NN system. This suggests buses are a better choice for systems that do not require many simultaneous communications or systems with broadcast communications like a fully-connected feed-forward NN. Results from the experiments with dynamic partial reconfiguration demonstrate that buses have the advantages of better resource utilization and smaller reconfiguration time and memory than NoCs. However, NoCs are more flexible and expansible. They have the advantage of placing almost all of the communication infrastructure in the dynamic reconfiguration region. This means that different applications running on the FPGA can use different interconnection strategies without the overhead of fixed bus resources in the static region. Another objective of the research is to examine the partial reconfiguration process and reconfiguration overhead with current FPGA technologies. Partial reconfiguration allows users to efficiently change the number of running PEs to choose an optimal powerperformance operating point at the minimum cost of reconfiguration. However, this brings drawbacks including resource utilization inefficiency, power consumption overhead and decrease in system operating frequency. The experimental results report a 50% of resource utilization inefficiency with a power consumption overhead of less than 5% and a decrease in frequency of up to 32% compared to a static implementation. The results also show that most of the drawbacks of partial reconfiguration implementation come from the restrictions and limitations of partial reconfiguration design flow. If these limitations can be addressed, partial reconfiguration should still be considered with its potential benefits.Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 201

MGSim - Simulation tools for multi-core processor architectures

MGSim is an open source discrete event simulator for on-chip hardware components, developed at the University of Amsterdam. It is intended to be a research and teaching vehicle to study the fine-grained hardware/software interactions on many-core and hardware multithreaded processors. It includes support for core models with different instruction sets, a configurable multi-core interconnect, multiple configurable cache and memory models, a dedicated I/O subsystem, and comprehensive monitoring and interaction facilities. The default model configuration shipped with MGSim implements Microgrids, a many-core architecture with hardware concurrency management. MGSim is furthermore written mostly in C++ and uses object classes to represent chip components. It is optimized for architecture models that can be described as process networks.Comment: 33 pages, 22 figures, 4 listings, 2 table

Design Approach to Implementation Of Arbitration Algorithm In Shared Bus Architectures (MPSoC)

The multiprocessor SoC designs have more than one processor and huge memory on the same chip. SoC consists of hardware cores and software cores ,multiple processors, embedded DRAM and connectors between cores .A wide range of MPSOC architectures have been developed over the past decade. This paper surveys the history of various On-Chip communication architectures present in the design of MPSoC. This acts as a primary factor of overall performance in complex SoC designs. Some of the various techniques that have driven the design of MpSoC has been discussed. Dynamically configurable communication architectures are found to improve the system performance. Currently On-chip interconnection networks are mostly implemented using shared buses which are the most common medium. The arbitration plays a crucial role in determining performance of bus-based system, as it assigns priorities, with which processor is granted the access to the shared communication resources. In the conventional arbitration algorithms there are some drawbacks such as bus starvation problem and low system performance. The bus should provide each component a flexible and utmost share of on-chip communication bandwidth and should improve the latency in access of the shared bus. The performance of SoC is improved using the probabilistic round robin algorithm with regard to the parameters, latency.Thus in this paper various issues related to bus arbitration related to design of MPSoC is analysed

A Dynamically Reconfigurable Parallel Processing Framework with Application to High-Performance Video Processing

Digital video processing demands have and will continue to grow at unprecedented rates. Growth comes from ever increasing volume of data, demand for higher resolution, higher frame rates, and the need for high capacity communications. Moreover, economic realities force continued reductions in size, weight and power requirements. The ever-changing needs and complexities associated with effective video processing systems leads to the consideration of dynamically reconfigurable systems. The goal of this dissertation research was to develop and demonstrate the viability of integrated parallel processing system that effectively and efficiently apply pre-optimized hardware cores for processing video streamed data. Digital video is decomposed into packets which are then distributed over a group of parallel video processing cores. Real time processing requires an effective task scheduler that distributes video packets efficiently to any of the reconfigurable distributed processing nodes across the framework, with the nodes running on FPGA reconfigurable logic in an inherently Virtual\u27 mode. The developed framework, coupled with the use of hardware techniques for dynamic processing optimization achieves an optimal cost/power/performance realization for video processing applications. The system is evaluated by testing processor utilization relative to I/O bandwidth and algorithm latency using a separable 2-D FIR filtering system, and a dynamic pixel processor. For these applications, the system can achieve performance of hundreds of 640x480 video frames per second across an eight lane Gen I PCIe bus. Overall, optimal performance is achieved in the sense that video data is processed at the maximum possible rate that can be streamed through the processing cores. This performance, coupled with inherent ability to dynamically add new algorithms to the described dynamically reconfigurable distributed processing framework, creates new opportunities for realizable and economic hardware virtualization.\u2