06141 Abstracts Collection -- Dynamically Reconfigurable Architectures

From 02.04.06 to 07.04.06, the Dagstuhl Seminar 06141 ``Dynamically Reconfigurable Architectures\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

High-Level Synthesis Hardware Design for FPGA-Based Accelerators: Models, Methodologies, and Frameworks

Hardware accelerators based on field programmable gate array (FPGA) and system on chip (SoC) devices have gained attention in recent years. One of the main reasons is that these devices contain reconfigurable logic, which makes them feasible for boosting the performance of applications. High-level synthesis (HLS) tools facilitate the creation of FPGA code from a high level of abstraction using different directives to obtain an optimized hardware design based on performance metrics. However, the complexity of the design space depends on different factors such as the number of directives used in the source code, the available resources in the device, and the clock frequency. Design space exploration (DSE) techniques comprise the evaluation of multiple implementations with different combinations of directives to obtain a design with a good compromise between different metrics. This paper presents a survey of models, methodologies, and frameworks proposed for metric estimation, FPGA-based DSE, and power consumption estimation on FPGA/SoC. The main features, limitations, and trade-offs of these approaches are described. We also present the integration of existing models and frameworks in diverse research areas and identify the different challenges to be addressed

IP-Enabled C/C++ Based High Level Synthesis: A Step towards Better Designer Productivity and Design Performance

Intellectual property (IP) core based design is an emerging design methodology to deal with increasing chip design complexity. C/C++ based high level synthesis (HLS) is also gaining traction as a design methodology to deal with increasing design complexity. In the work presented here, we present a design methodology that combines these two individual methodologies and is therefore more powerful. We discuss our proposed methodology in the context of supporting efficient hardware synthesis of a class of mathematical functions without altering original C/C++ source code. Additionally, we also discuss and propose methods to integrate legacy IP cores in existing HLS flows. Relying on concepts from the domains of program recognition and optimized low level implementations of such arithmetic functions, the described design methodology is a step towards intelligent synthesis where application characteristics are matched with specific architectural resources and relevant IP cores in a transparent manner for improved area-delay results. The combined methodology is more aware of the target hardware architecture than the conventional HLS flow. Implementation results of certain compute kernels from a commercial tool Vivado-HLS as well as proposed flow are also compared to show that proposed flow gives better results

Energy efficient enabling technologies for semantic video processing on mobile devices

Semantic object-based processing will play an increasingly important role in future multimedia systems due to the ubiquity of digital multimedia capture/playback technologies and increasing storage capacity. Although the object based paradigm has many undeniable benefits, numerous technical challenges remain before the applications becomes pervasive, particularly on computational constrained mobile devices. A fundamental issue is the ill-posed problem of semantic object segmentation. Furthermore, on battery powered mobile computing devices, the additional algorithmic complexity of semantic object based processing compared to conventional video processing is highly undesirable both from a real-time operation and battery life perspective. This thesis attempts to tackle these issues by firstly constraining the solution space and focusing on the human face as a primary semantic concept of use to users of mobile devices. A novel face detection algorithm is proposed, which from the outset was designed to be amenable to be offloaded from the host microprocessor to dedicated hardware, thereby providing real-time performance and reducing power consumption. The algorithm uses an Artificial Neural Network (ANN), whose topology and weights are evolved via a genetic algorithm (GA). The computational burden of the ANN evaluation is offloaded to a dedicated hardware accelerator, which is capable of processing any evolved network topology. Efficient arithmetic circuitry, which leverages modified Booth recoding, column compressors and carry save adders, is adopted throughout the design. To tackle the increased computational costs associated with object tracking or object based shape encoding, a novel energy efficient binary motion estimation architecture is proposed. Energy is reduced in the proposed motion estimation architecture by minimising the redundant operations inherent in the binary data. Both architectures are shown to compare favourable with the relevant prior art

Image Processing Using FPGAs

This book presents a selection of papers representing current research on using field programmable gate arrays (FPGAs) for realising image processing algorithms. These papers are reprints of papers selected for a Special Issue of the Journal of Imaging on image processing using FPGAs. A diverse range of topics is covered, including parallel soft processors, memory management, image filters, segmentation, clustering, image analysis, and image compression. Applications include traffic sign recognition for autonomous driving, cell detection for histopathology, and video compression. Collectively, they represent the current state-of-the-art on image processing using FPGAs

Distributed Processing in FPGA Accelerated Cloud

Motivated by the need of cost reduction, better energy efficiency and agile update and deployment of new services, telecommunication industry is moving towards virtualization, which lead to Network Function Virtualization (NFV) standard. NFV leverages cloud technologies to deploy network functions that are traditionally implemented using dedicated proprietary hardware. Still, the performance provided by current cloud infrastructure does not fulfill the requirements for demanding NFV's use cases. Thus, hardware acceleration should be deployed. The hardware programmability of FPGAs allows them to adapt well to many type of workloads, placing them as good candidates to be used as hardware accelerators in virtualized environments. In this thesis, the CRUN framework is proposed to provide FPGA as hardware accelerator resources in cloud, abstracting the integration complexity while enabling sharable and scalable use of such devices. CRUN architecture allow user's acceleration hardware to be accessed locally and through the datacenter's network. The latter provide flexible connectivity by following the Software-defined Networking (SDN) principles. The architecture enables the same sharable FPGA to be used simultaneously as a co-processor, a network accelerator or as a distributed accelerator in a scalable scenario over several FPGAs. In its current development state, CRUN was leveraged for inference of a machine learning application composed of a fully connected neural network. The main performance target was to achieve ultra-low latency, less than 40μs, for each inference at software level. Only CRUN fulfilled the requirement among the analyzed alternatives, where the architecture is capable of providing latency in the 30μs range in average. For context, high-end General-Purpose Processor (GPP) and Graphics Processing Unit (GPU) provided latency values of 798μs and 1 897μs respectively for the same application

Energy efficient hardware acceleration of multimedia processing tools

The world of mobile devices is experiencing an ongoing trend of feature enhancement and generalpurpose multimedia platform convergence. This trend poses many grand challenges, the most pressing being their limited battery life as a consequence of delivering computationally demanding features. The envisaged mobile application features can be considered to be accelerated by a set of underpinning hardware blocks Based on the survey that this thesis presents on modem video compression standards and their associated enabling technologies, it is concluded that tight energy and throughput constraints can still be effectively tackled at algorithmic level in order to design re-usable optimised hardware acceleration cores. To prove these conclusions, the work m this thesis is focused on two of the basic enabling technologies that support mobile video applications, namely the Shape Adaptive Discrete Cosine Transform (SA-DCT) and its inverse, the SA-IDCT. The hardware architectures presented in this work have been designed with energy efficiency in mind. This goal is achieved by employing high level techniques such as redundant computation elimination, parallelism and low switching computation structures. Both architectures compare favourably against the relevant pnor art in the literature. The SA-DCT/IDCT technologies are instances of a more general computation - namely, both are Constant Matrix Multiplication (CMM) operations. Thus, this thesis also proposes an algorithm for the efficient hardware design of any general CMM-based enabling technology. The proposed algorithm leverages the effective solution search capability of genetic programming. A bonus feature of the proposed modelling approach is that it is further amenable to hardware acceleration. Another bonus feature is an early exit mechanism that achieves large search space reductions .Results show an improvement on state of the art algorithms with future potential for even greater savings

Efficient Real-Time Architectures and FPGA Implementations of Histogram-Based Median Filters for High Definition Videos

Digital filtering plays an important role in many signal processing applications. Filtering is performed to recover the original signal from its corrupted version. Median filter is a non-linear digital filter that replaces a sample in a given window by the median value of the samples in the window. For images corrupted with impulse noise, median filter provides a very high quality of filtered images. Several modifications of median filters have been proposed and implemented to achieve high image quality compared to that provided by conventional median filters. When these filters are implemented on hardware platforms such as FPGAs, the performance parameters, namely, the area, power and operating frequency should be taken into consideration in addition to the quality of the filtered image. Therefore, efficient implementation of median filters on FPGAs for image and video processing algorithms has been a topic of much interest. The existing hardware-based median filters for high definition video formats do not always satisfy the real-time throughput requirements or are inefficient with respect to hardware performance parameters, such as the area and frequency. This is due to the fact that most of the existing techniques use sorting-based median calculation, which results in a low hardware performance. In this thesis, architectures that use histogram-based median computation, which is a non-sorting-based operation, are designed with a view of efficient hardware implementation. This is carried out in two parts. We design and implement efficient architectures that satisfy the real-time throughput requirements of full high definition (FHD) videos in the first part and that of ultra high definition (UHD) videos in the second part. In the first part, an efficient real-time histogram-based median filter that uses the concept of bit-plane-slicing and adaptive switching median filter (ASMF) is designed and implemented on FPGAs. We term this architecture as hybrid architecture for median filtering (HAMF). The proposed HAMF computes an approximate median, since it uses only the most significant B-bits of the pixel values for median calculation. As a result, the algorithmic level implementation of the proposed HAMF results in a slight degradation in the filtered image quality compared to that provided by ASMF. The proposed HAMF provides a significant improvement over ASMF in terms of the area and operating frequency, when implemented on different generation FPGAs. Analysis of the different parameters, such as the number of bit-planes used in the computation of the median and the number of pipelining stages, is carried out to study the trade-off between the quality of the filtered image and hardware performance. Although the FPGA implementation of the proposed HAMF provides a very high operating frequency, the quality of the images filtered by its algorithmic level implementation decreases with increasing window size and noise density. This filter may be suitable for applications that require FHD filtering with cost constraints, but not for applications where the output image quality is as important as the hardware performance. Hence, in the second part, we design an efficient and real-time architecture of the hierarchical histogram-based median filter (HHMF). The proposed architecture is designed using a full synchronous pipeline, a synchronous accumulate-and-compare unit, and is scalable. The FPGA implementation of the proposed architecture of HHMF can perform real-time filtering of 4K and 8K UHD videos. The quality of the image filtered by HHMF is not compromised as in the case of HAMF, since HHMF uses all the bit-planes and computes the actual median. Although the FPGA implementation of HHMF results in more area utilization, the proposed implementation is more economical than a GPU-based HHMF implementation and provides a better throughput