Design of testbed and emulation tools

The research summarized was concerned with the design of testbed and emulation tools suitable to assist in projecting, with reasonable accuracy, the expected performance of highly concurrent computing systems on large, complete applications. Such testbed and emulation tools are intended for the eventual use of those exploring new concurrent system architectures and organizations, either as users or as designers of such systems. While a range of alternatives was considered, a software based set of hierarchical tools was chosen to provide maximum flexibility, to ease in moving to new computers as technology improves and to take advantage of the inherent reliability and availability of commercially available computing systems

Parallelism through Digital Circuit Design

Two ways to exploit chips with a very large number of transistors are multicore processors and programmable logic chips. Some data parallel algorithms can be executed efficiently on ordinary parallel computers, including multicores. A class of data parallel algorithms is identified which have characteristics that make implementation on multiprocessors inefficient, but they are well suited for direct design as digital circuits. This leads to a programming model called circuit parallelism. The characteristics of circuit parallel algorithms are discussed, and a prototype system for supporting them is described

Reconfiguration for Fault Tolerance and Performance Analysis

Architecture reconfiguration, the ability of a system to alter the active interconnection among modules, has a history of different purposes and strategies. Its purposes develop from the relatively simple desire to formalize procedures that all processes have in common to reconfiguration for the improvement of fault-tolerance, to reconfiguration for performance enhancement, either through the simple maximizing of system use or by sophisticated notions of wedding topology to the specific needs of a given process. Strategies range from straightforward redundancy by means of an identical backup system to intricate structures employing multistage interconnection networks. The present discussion surveys the more important contributions to developments in reconfigurable architecture. The strategy here is in a sense to approach the field from an historical perspective, with the goal of developing a more coherent theory of reconfiguration. First, the Turing and von Neumann machines are discussed from the perspective of system reconfiguration, and it is seen that this early important theoretical work contains little that anticipates reconfiguration. Then some early developments in reconfiguration are analyzed, including the work of Estrin and associates on the fixed plus variable restructurable computer system, the attempt to theorize about configurable computers by Miller and Cocke, and the work of Reddi and Feustel on their restructable computer system. The discussion then focuses on the most sustained systems for fault tolerance and performance enhancement that have been proposed. An attempt will be made to define fault tolerance and to investigate some of the strategies used to achieve it. By investigating four different systems, the Tandern computer, the C.vmp system, the Extra Stage Cube, and the Gamma network, the move from dynamic redundancy to reconfiguration is observed. Then reconfiguration for performance enhancement is discussed. A survey of some proposals is attempted, then the discussion focuses on the most sustained systems that have been proposed: PASM, the DC architecture, the Star local network, and the NYU Ultracomputer. The discussion is organized around a comparison of control, scheduling, communication, and network topology. Finally, comparisons are drawn between fault tolerance and performance enhancement, in order to clarify the notion of reconfiguration and to reveal the common ground of fault tolerance and performance enhancement as well as the areas in which they diverge. An attempt is made in the conclusion to derive from this survey and analysis some observations on the nature of reconfiguration, as well as some remarks on necessary further areas of research

A bibliography on parallel and vector numerical algorithms

This is a bibliography of numerical methods. It also includes a number of other references on machine architecture, programming language, and other topics of interest to scientific computing. Certain conference proceedings and anthologies which have been published in book form are listed also

Parallel Architectures for Planetary Exploration Requirements (PAPER)

The Parallel Architectures for Planetary Exploration Requirements (PAPER) project is essentially research oriented towards technology insertion issues for NASA's unmanned planetary probes. It was initiated to complement and augment the long-term efforts for space exploration with particular reference to NASA/LaRC's (NASA Langley Research Center) research needs for planetary exploration missions of the mid and late 1990s. The requirements for space missions as given in the somewhat dated Advanced Information Processing Systems (AIPS) requirements document are contrasted with the new requirements from JPL/Caltech involving sensor data capture and scene analysis. It is shown that more stringent requirements have arisen as a result of technological advancements. Two possible architectures, the AIPS Proof of Concept (POC) configuration and the MAX Fault-tolerant dataflow multiprocessor, were evaluated. The main observation was that the AIPS design is biased towards fault tolerance and may not be an ideal architecture for planetary and deep space probes due to high cost and complexity. The MAX concepts appears to be a promising candidate, except that more detailed information is required. The feasibility for adding neural computation capability to this architecture needs to be studied. Key impact issues for architectural design of computing systems meant for planetary missions were also identified

Evolving hardware with genetic algorithms

Genetic techniques are applied to the problem of electronic circuit design, with an emphasis on VLSI circuits. The goal is to have a tool which has the performance and flexibility to attack a wide range of problems. A genetic algorithm is used to design a circuit specified by the desired input /output characteristics. A software system is implemented to synthesize and optimize circuits using an asynchronous parallel genetic algorithm. The software is designed with object-oriented constructs in order to maintain scalability and provide for future enhancements. The system is executed on a heterogeneous network of workstations ranging from Sun Sparc Ultras to HP multiprocessors. Testing of this software is done with examples of both digital and analog CMOS VLSI circuits. Performance is measured in both the quality of the solutions and in the time it took to evolve them

A Shared memory multiprocessor system architecture utilizing a uniform

Due to VLSI lithography problems and the limitation of additional architectural enhancements uniprocessor systems are nearing the end of their life cycle. Therefore, it is believed that Symmetric Multiprocessing (SMP) systems will be the next mainstream computer. These systems allow multiple processors, accessing the same memory image, to cooperate on a number of computational tasks as a single entity. While multiprocessor systems can offer a substantial performance increase compared to uniprocessor systems, major design considerations must be addressed to achieve desired system efficiency levels. Managing cache coherence is a significant problem in multiprocessor systems. Current implementations cope with this problem by utilizing a cache coherence protocol. This protocol puts a large amount of overhead on the system bus to ensure proper program execution, effectively decreasing overall system performance. This thesis approaches the cache coherence problem from a new angle. Instead of utilizing a cache coherence protocol, a new memory system is proposed which eliminates the need for a cache coherence protocol, by utilizing a shared level 2 data-only cache. This new architecture allows for better utilization of the system and improved performance and scalability. A data rate analysis is conducted to demonstrate the potential performance increase from the proposed architecture over conventional approaches. The data rate model clearly shows an increase in system performance and utilization when using the architecture proposed in this thesis

Solution of partial differential equations on vector and parallel computers

The present status of numerical methods for partial differential equations on vector and parallel computers was reviewed. The relevant aspects of these computers are discussed and a brief review of their development is included, with particular attention paid to those characteristics that influence algorithm selection. Both direct and iterative methods are given for elliptic equations as well as explicit and implicit methods for initial boundary value problems. The intent is to point out attractive methods as well as areas where this class of computer architecture cannot be fully utilized because of either hardware restrictions or the lack of adequate algorithms. Application areas utilizing these computers are briefly discussed

The Use of Parallel Processing in VLSI Computer-Aided Design Application

Coordinated Science Laboratory was formerly known as Control Systems LaboratorySemiconductor Research Corporation / 87-DP-10