123 research outputs found

    Analysis of a benchmark suite to evaluate mixed numeric and symbolic processing

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    The suite of programs that formed the benchmark for a proposed advanced computer is described and analyzed. The features of the processor and its operating system that are tested by the benchmark are discussed. The computer codes and the supporting data for the analysis are given as appendices

    M̲, a memory manager for Ḻ

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    Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1988.Characters with an underscore appear as italic on the t.p.Bibliography: leaves 94-95.by Andrew Edward Ayers.M.S

    Analysis of some algorithms for use on paged virtual memory computers

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    PhD ThesisHandling a single page fault involves execution of thousands of instructions, drum rotational delay and is usually so expensive that if it can be avoided, almost any other cost can be tolerated. Optimizing operating system performance is usually the main concern of computer seientists who deal with paged memories. However, redesigning the algorithm used by a problem program can often result in a very significant reduction in paging, and hence in program execution time. The redesigned algorithm frequently does not satisfy the more conventional efficiency criteria. A sorting algorithm, Hash Coding and other search algorithms are considered. Analytic and simulation studies are presented, and aome modifications are proposed to reduce the number of page faults produced by data set references. Analysis is in terms of three of the most commonly used page replacement algorithms i.e. least recently used, first in first out, and random selection. The modifications are for the most part relatively minor and in some cases have appeared elsewhere in the context of searching on external storage media. The important aspects are the dramatic performance improvements which are possible, and the fact that classical internal algorithms are inappropriate for use in a paged virtual memory system.The Science Research Council: The University of Newcastle Upon Tyne: International Business Machines (United Kingdom) Limited.

    An abstract machine for parallel graph reduction

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    technical reportAn abstract machine for parallel graph reduction on a shared memory multiprocessor is described. This is intended primarily for normal order (lazy) evaluation of functional programs. It is absolutely essential in such a design to adapt an efficient sequential model since during execution under limited resources available, performance will be reduced in the limit to that of the sequential engine. Parallel evaluation of normal order functional languages performed naively can result in poor overall performance despite the availability of sufficient processing elements and parallelism in the application. Needless context switching, task migration and continuation building may occur when a sequential thread of control would have sufficed. Furthermore, the compiler using static information cannot be fully aware of the availability of resources and their optimal utilization at any moment in run time. Indeed this may vary between runs which further aggravates the job of the compiler writer in generating optimal and compact code for programs. The benefits derived from this model are: 1) it is based on the G-machine so that execution under limited resources will default to a performance close to that of the G-machine; 2) the additional instructions needed to control the complexities of parallel evaluation are extremely simple, almost trivializing the job of the compiler writer; 3) attempts are made where possible to avoid context switching and task migration by retaining a sequential thread of control (made more clear in the paper), and 4) the method has demonstrated good overall performance on a shared memory multiprocessor

    Garbage Collection of Linked Data Structures: An Example in a Network Oriented Database Management System

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    A unified view of the numerous existing algorithms for performing garbage collection of linked data structure has been presented. An implementation of a garbage collection tool in a network oriented database management system has been described

    Garbage collection in distributed systems

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    PhD ThesisThe provision of system-wide heap storage has a number of advantages. However, when the technique is applied to distributed systems automatically recovering inaccessible variables becomes a serious problem. This thesis presents a survey of such garbage collection techniques but finds that no existing algorithm is entirely suitable. A new, general purpose algorithm is developed and presented which allows individual systems to garbage collect largely independently. The effects of these garbage collections are combined, using recursively structured control mechanisms, to achieve garbage collection of the entire heap with the minimum of overheads. Experimental results show that new algorithm recovers most inaccessible variables more quickly than a straightforward garbage collection, giving an improved memory utilisation

    A software cache management system

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    Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERINGBibliography: leaves 49-50.by Jeffrey N. Eisen.M.S

    Compilation techniques for irregular problems on parallel machines

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    Massively parallel computers have ushered in the era of teraflop computing. Even though large and powerful machines are being built, they are used by only a fraction of the computing community. The fundamental reason for this situation is that parallel machines are difficult to program. Development of compilers that automatically parallelize programs will greatly increase the use of these machines.;A large class of scientific problems can be categorized as irregular computations. In this class of computation, the data access patterns are known only at runtime, creating significant difficulties for a parallelizing compiler to generate efficient parallel codes. Some compilers with very limited abilities to parallelize simple irregular computations exist, but the methods used by these compilers fail for any non-trivial applications code.;This research presents development of compiler transformation techniques that can be used to effectively parallelize an important class of irregular programs. A central aim of these transformation techniques is to generate codes that aggressively prefetch data. Program slicing methods are used as a part of the code generation process. In this approach, a program written in a data-parallel language, such as HPF, is transformed so that it can be executed on a distributed memory machine. An efficient compiler runtime support system has been developed that performs data movement and software caching
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