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Articles 331 - 360 of 532

Full-Text Articles in Computer Sciences

Passion Runtime Library For Parallel I/O, Rajeev Thakur, Rajesh Bordawekar, Alok Choudhary, Ravi Ponnusamy Jan 1994

Passion Runtime Library For Parallel I/O, Rajeev Thakur, Rajesh Bordawekar, Alok Choudhary, Ravi Ponnusamy

Electrical Engineering and Computer Science - All Scholarship

We are developing a compiler and runtime support system called PASSION: Parallel And Scalable Software for Input-Output. PASSION provides software support for I/O intensive out-of-core loosely synchronous problems. This paper gives an overview of the PASSION Runtime Library and describes two of the optimizations incorporated in it, namely Data Prefetching and Data Sieving. Performance improvements provided by these optimizations on the Intel Touchstone Delta are discussed, together with an out of -core Median Filtering application.

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Design Of An Application Development Toolkit For Hpf/Fortran 90d, Manish Parashar, Salim Hariri, Tomasz Haupt, Geoffrey C. Fox Jan 1994

Design Of An Application Development Toolkit For Hpf/Fortran 90d, Manish Parashar, Salim Hariri, Tomasz Haupt, Geoffrey C. Fox

Northeast Parallel Architecture Center

The development of efficient application software capable of exploiting available High Performance Computing (HPC) systems is non-trivial and is largely governed by the availability of sufficiently high-level languages, tools, and application development environments. In this paper we describe the design and operation of a toolkit for HPF/Fortran 90D application development. The toolkit incorporates the following systems: (1) ESP: An Interpretive Framework for HPF/Fortran 90D Performance Prediction; (2) ESP-i: A HPF/Fortran 90D Functional Interpreter; and (3) ESPial: An Integrated Environment for HPF/Fortran 90D Application Development & Execution. The toolkit has been implemented on the iPSC/860 hypercube system, and is supported by …

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Interpreting The Performance Of Hpf/Fortran 90d, Manish Parashar, Salim Hariri, Tomasz Haupt, Geoffrey C. Fox Jan 1994

Interpreting The Performance Of Hpf/Fortran 90d, Manish Parashar, Salim Hariri, Tomasz Haupt, Geoffrey C. Fox

Northeast Parallel Architecture Center

In this paper we present a novel interpretive approach for accurate and cost-effective performance prediction in a high performance computing environment, and describe the design of a source-driven HPF/Fortran 90D performance prediction framework based on this approach. The performance prediction framework has been implemented as part of a HPF/Fortran 90D application development environment. A set of benchmarking kernels and application codes are used to validate the accuracy, utility, usability, and cost-effectiveness of the performance prediction framework. The use of the framework for selecting appropriate compiler directives and for application performance debugging is demonstrated. Keywords: Performance prediction, HPF/Fortran 90D application development, …

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Run-Time And Compile-Time Support For Adaptive Irregular Problems, Shamik D. Sharma, Ravi Ponnusamy, Bongki Moon, Yuan-Shin Hwang Jan 1994

Run-Time And Compile-Time Support For Adaptive Irregular Problems, Shamik D. Sharma, Ravi Ponnusamy, Bongki Moon, Yuan-Shin Hwang

Northeast Parallel Architecture Center

In adaptive irregular problems the data arrays are accessed via indirection arrays, and data access patterns change during computation. Implementing such problems on distributed memory machines requires support for dynamic data partitioning, efficient preprocessing and fast data migration. This research presents efficient runtime primitives for such problems. This new set of primitives is part of the CHAOS library. It subsumes the previous PARTI library which targeted only static irregular problems. To demonstrate the efficacy of the runtime support, two real adaptive irregular applications have been parallelized using CHAOS primitives: a molecular dynamics code (CHARMM) and a particle-in-cell code (DSMC). The …

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Compiling Fortran 90d/Hpf For Distributed Memory Mimd Computers, Zeki Bozkus, Alok Choudhary, Geoffrey C. Fox, Tomasz Haupt Jan 1994

Compiling Fortran 90d/Hpf For Distributed Memory Mimd Computers, Zeki Bozkus, Alok Choudhary, Geoffrey C. Fox, Tomasz Haupt

Northeast Parallel Architecture Center

This paper describes the design of the Fortran90D/HPF compiler, a source-to-source parallel compiler for distributed memory systems being developed at Syracuse University. Fortran 90D/HPF is a data parallel language with special directives to specify data alignment and distributions. A systematic methodology to process distribution directives of Fortran 90D/HPF is presented. Furthermore, techniques for data and computation partitioning, communication detection and generation, and the run-time support for the compiler are discussed. Finally, initial performance results for the compiler are presented. We believe that the methodology to process data distribution, computation partitioning, communication system design and the overall compiler design can be …

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Mapping Algorithms And Software Environment For Data Parallel, Nikos Chrisochoides, Elias Houstis, John Rice Jan 1994

Mapping Algorithms And Software Environment For Data Parallel, Nikos Chrisochoides, Elias Houstis, John Rice

Northeast Parallel Architecture Center

We consider computations associated with data parallel iterative solvers used for the numerical solution of Partial Differential Equations (PDEs). The mapping of such computations into load balanced tasks requiring minimum synchronization and communication is a difficult combinatorial optimization problem. Its optimal solution is essential for the efficient parallel processing of PDE computations. Determining data mappings that optimize a number of criteria, like workload balance, synchronization and local communication, often involves the solution of an NP-Complete problem. Although data mapping algorithms have been known for a few years there is lack of qualitative and quantitative comparisons based on the actual performance …

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Runtime Array Redistribution In Hpf Programs, Rajeev Thakur, Alok Choudhary, Geoffrey C. Fox Jan 1994

Runtime Array Redistribution In Hpf Programs, Rajeev Thakur, Alok Choudhary, Geoffrey C. Fox

Northeast Parallel Architecture Center

This paper describes efficient algorithms for runtime array redistribution in HPF programs. We consider block(m) to cyclic, cyclic to block(m) and the general cyclic(x) to cyclic(y) type redistributions. We initially describe algorithms for one-dimensional arrays and then extend the methodology to multidimensional arrays. The algorithms are practical enough to be easily implemented in the runtime library of an HPF compiler and can also be directly used in application programs requiring redistribution. Performance results on the Intel Paragon are discussed.

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Analysis Of Random Number Generators Using Monte Carlo Simulation, Paul D. Coddington Jan 1994

Analysis Of Random Number Generators Using Monte Carlo Simulation, Paul D. Coddington

Northeast Parallel Architecture Center

Monte Carlo simulation is one of the main applications involving the use of random number generators. It is also one of the best methods of testing the randomness properties of such generators, by comparing results of simulations using different generators with each other, or with analytic results. Here we compare the performance of some popular random number generators by high precision Monte Carlo simulation of the 2-d Ising model, for which exact results are known, using the Metropolis, Swendsen-Wang, and Wolff Monte Carlo algorithms. Many widely used generators that perform well in standard statistical tests are shown to fail these …

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Supporting Irregular Distributions In Fortran 90d/Hpf Compilers, Ravi Ponnusamy, Yuan-Shin Hwang, Raja Das, Joel Saltz Jan 1994

Supporting Irregular Distributions In Fortran 90d/Hpf Compilers, Ravi Ponnusamy, Yuan-Shin Hwang, Raja Das, Joel Saltz

Northeast Parallel Architecture Center

This paper presents methods that make it possible to efficiently support irregular problems using data parallel languages. The approach involves the use of a portable, compiler-independent, runtime support library called CHAOS. The CHAOS runtime support library contains procedures that (1) support static and dynamic distributed array partitioning, (2) partition loop iterations and indirection arrays, (3) remap arrays from one distribution to another, and (4) carry out index translation, buffer allocation and communication schedule generation. The CHAOS runtime procedures are used by a prototype Fortran 90D compiler as runtime support for irregular problems. This paper also presents performance results of compiler-generated …

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The Design And Evolution Of Zipcode, Anthony Skjellum, Steven G. Smith, Nathan E. Doss, Alvin Leung Jan 1994

The Design And Evolution Of Zipcode, Anthony Skjellum, Steven G. Smith, Nathan E. Doss, Alvin Leung

Northeast Parallel Architecture Center

Zipcode is a message-passing and process-management system that was designed for multicomputers and homogeneous networks of computers in order to support libraries and large-scale multicomputer software. The system has evolved significantly over the last five years, based on our experiences and identified needs. Features of Zipcode that were originally unique to it, were its simultaneous support of static process groups, communication contexts, and virtual topologies, forming the "mailer" data structure. Point-to-point and collective operations reference the underlying group, and use contexts to avoid mixing up messages. Recently, we have added "gather-send" and "receive-scatter" semantics, based on persistent Zipcode "invoices," both …

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A Communication System For High-Performance Distributed Computing, Salim Hariri, Jongbaek Park, Manish Parashar, Geoffrey C. Fox Jan 1994

A Communication System For High-Performance Distributed Computing, Salim Hariri, Jongbaek Park, Manish Parashar, Geoffrey C. Fox

Northeast Parallel Architecture Center

With the current advances in computer and networking technology coupled with the availability of software tools for parallel and distributed computing, there has been increased interests in high-performance distributed computing (HPDC). We envision that HPDC environments with supercomputing capabilities will be available in the near future. However, a number of issues have to be resolved before future network-based applications can exploit fully the potential of HPDC environment. In this paper, we present an architecture of a high-speed local area network and a communication system that provides HPDC applications with high bandwidth and low latency. We also characterize the message-passing primitives …

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Developing Interactive Pvm-Based Parallel Programs On Distributed Computing Systems Within Avs Framework, Gang Cheng, Geoffrey C. Fox, Kim Mills, Marek Podgorny Jan 1994

Developing Interactive Pvm-Based Parallel Programs On Distributed Computing Systems Within Avs Framework, Gang Cheng, Geoffrey C. Fox, Kim Mills, Marek Podgorny

Northeast Parallel Architecture Center

We discuss techniques in developing interactive Parallel Virtual Machine (PVM) concurrent programs on distributed systems under AVS framework. Using a stock option price modeling application as a case study, we demonstrate a simple, effective and modular approach to coupling network-based concurrent modules into an interactive remote visualization environment. A prototype simulation on-demand system is developed, in which parallel option pricing models locally implemented on two distributed systems, an Ethernet-connected IBM SP1 and a FDDI-based GIGswitch-connected DEC Alpha farm, are coupled with an interactive graphical user interface over a ATM-based wide area network. This integrated networking/visualization framework allows one to use …

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Involvement Of Industry In The National High Performance Computing And Communication Enterprise, Geoffrey C. Fox Jan 1994

Involvement Of Industry In The National High Performance Computing And Communication Enterprise, Geoffrey C. Fox

Northeast Parallel Architecture Center

We discuss aspects of a national computer science agenda for High Performance Computing and Communications (HPCC). We agree with the general direction and emphasis of the current program. In particular, the strong experimental component and linkage of applications with computer science should be continued. We recommend accelerating the emphasis on "national challenges " with more applications and technologies from the information, as compared to simulation areas. We suggest modifying the grand challenge concept to complement the current teaming of particular computer science and applications researchers. We would emphasize better linking of each application group to the entire (inter) national computer …

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A Study Of Software Development For High Performance Computing, Manish Parashar, Salim Hariri, Tomasz Haupt, Geoffrey C. Fox Jan 1994

A Study Of Software Development For High Performance Computing, Manish Parashar, Salim Hariri, Tomasz Haupt, Geoffrey C. Fox

Northeast Parallel Architecture Center

Software development in a High Performance Computing (HPC) environment is non-trivial and requires a thorough understanding of the application and the architecture. The objective of this paper is to study the software development process in a high performance computing environment and to outline the stages typically encountered in this process. Support required at each stage is also highlighted. The modeling of stock option pricing is used as a running example in the study.

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Developing Modular Application Builders To Exploit Mimd Parallel Resources, C. Thornborrow, C. Faigle Jan 1994

Developing Modular Application Builders To Exploit Mimd Parallel Resources, C. Thornborrow, C. Faigle

Northeast Parallel Architecture Center

Modular application builders (MABs), such as AVS and Iris Explorer[6, 7] are increasingly being used in the visualisation community. Such systems can already place compute intensive modules on supercomputers in order to utilise their power. This paper details two major projects at EPCC which attempted to fully integrate the MAB concept with a distributed memory MIMD (DM-MIMD) environment. The work presented was driven by two goals, efficient use of the resource and ease of use by programmer and end user. We present a model of MABs and describe the major problems faced, giving solutions to them through two case studies.

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Applications And Enabling Technology For Nynet Upstate Corridor, Salim Hariri, Geoffrey C. Fox Jan 1994

Applications And Enabling Technology For Nynet Upstate Corridor, Salim Hariri, Geoffrey C. Fox

Northeast Parallel Architecture Center

Current advances in telecommunication and computing will have significant impact on the proliferation of high performance computing and communication (HPCC) applications. With these emerging technologies, it is feasible to run parallel and distributed applications across a high speed wide area network which was not possible a few years ago; the high latency and low bandwidth were the main bottlenecks for the wide area network-based computing. This has lead to the deployment of several high speed networks across the country (eg. NYNET). In this report, we describe some of the HPCC applications and our experiences and lessons learned from running them …

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The Virtual Computing Environment, Philip Rousselle, Paul Tymann, Salim Hariri, Geoffrey C. Fox Jan 1994

The Virtual Computing Environment, Philip Rousselle, Paul Tymann, Salim Hariri, Geoffrey C. Fox

Northeast Parallel Architecture Center

A network of supercomputers and high-performance workstations appears to be the only reasonable way to provide adequate computing resources for the Grand Challenge problems of the next century. Such a collection of computers and supporting software environments is called a virtual computing environment (VCE). This paper describes the motivation and goals of the VCE project, followed by a description of the system. The paper concentrates on the runtime aspects of the VCE, and concludes with a discussion of a small prototype system that has been built using the Isis distributed toolkit.

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Data Access Reorganizations In Compiling Out-Of-Core Data Parallel Programs On Distributed Memory Machines, Rajesh Bordawekar, Alok Choudhary, Rajeev Thakur Jan 1994

Data Access Reorganizations In Compiling Out-Of-Core Data Parallel Programs On Distributed Memory Machines, Rajesh Bordawekar, Alok Choudhary, Rajeev Thakur

Electrical Engineering and Computer Science - All Scholarship

This paper describes techniques for translating out-of-core programs written in a data parallel language like HPF to message passing node programs with explicit parallel I/O. We describe the basic compilation model and various steps involved in the compilation. The compilation process is explained with the help of an out-of-core matrix multiplication program. We first discuss how an out-of-core program can be translated by extending the method used for translating in-core programs. We demonstrate that straightforward extension of in-core compiler does not work for out-of-core programs. We then describe how the compiler can optimize the code by (1) estimating the I/O …

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Passion: Parallel And Scalable Software For Input-Output, Alok Choudhary, Rajesh Bordawekar, Michael Harry, Rakesh Krishnaiyer Jan 1994

Passion: Parallel And Scalable Software For Input-Output, Alok Choudhary, Rajesh Bordawekar, Michael Harry, Rakesh Krishnaiyer

Electrical Engineering and Computer Science - All Scholarship

We are developing a software system called PASSION: Parallel And Scalable Software for Input-Output which provides software support for high performance parallel I/O. PASSION provides support at the language, compiler, runtime as well as file system level. PASSION provides runtime procedures for parallel access to files (read/write), as well as for out-of-core computations. These routines can either be used together with a compiler to translate out-of-core data parallel programs written in a language like HPF, or used directly by application programmers. A number of optimizations such as Two-Phase Access, Data Sieving, Data Prefetching and Data Reuse have been incorporated in …

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Genetic Algorithms For Soft Decision Decoding Of Linear Block Codes, Harpal Maini, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka Nov 1993

Genetic Algorithms For Soft Decision Decoding Of Linear Block Codes, Harpal Maini, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka

Electrical Engineering and Computer Science - Technical Reports

Soft-decision decoding is an NP-hard problem of great interest to developers of communication systems. We show that this problem is equivalent to the problem of optimizing Walsh polynomials. We present genetic algorithms for soft-decision decoding of binary linear block codes and compare the performance with various other decoding algorithms. Simulation results show that our algorithms achieve bit-error-probabilities as low as 0.00183 for a [104, 52] code with a low signal-to-noise ratio of 2.5 dB, exploring only 30,000 codewords, whereas the search space contains 4.5 x 1015 codewords. We define a new crossover operator that exploits domain-specific information and compare it …

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Parametricity And Local Variables, Peter W. O'Hearn, R. D. Tennent Oct 1993

Parametricity And Local Variables, Peter W. O'Hearn, R. D. Tennent

Electrical Engineering and Computer Science - Technical Reports

We propose that the phenomenon of local state may be understood in terms of Strachey's concept of parametric (i.e., uniform) polymorphism. The intuitive basis for our proposal is the following analogy: a non-local procedure is independent of locally-declared variables in the same way that a parametrically polymorphic function is independent of types to which it is instantiated. A connection between parametricity and representational abstraction was first suggested by J. C. Reynolds. Reynolds used logical relations to formalize this connection in languages with type variables and user-defined types. We use relational parametricity to construct a model for an Algol-like language in …

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Putting Humpty-Dumpty Together Again: Reconstructing Functions From Their Projections., Anil Ravindran Menon, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka Jun 1993

Putting Humpty-Dumpty Together Again: Reconstructing Functions From Their Projections., Anil Ravindran Menon, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka

Electrical Engineering and Computer Science - Technical Reports

We present a problem decomposition approach to reduce neural net training times. The basic idea is to train neural nets in parallel on marginal distributions obtained from the original distribution (via projection), and then reconstruct the original table from the marginals (via a procedure similar to the join operator in database theory). A function is said to be reconstructible, if it may be recovered without error from its projections. Most distributions are non-reconstructible. The main result of this paper is the Reconstruction theorem, which enables non-reconstructible functions to be expressed in terms of reconstructible ones, and thus facilitates the application …

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On Inverse Sigmoid Functions, Anil Ravindran Menon, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka Jun 1993

On Inverse Sigmoid Functions, Anil Ravindran Menon, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka

Electrical Engineering and Computer Science - Technical Reports

Networks with sigmoid node functions have been shown to be universal approximators, and can use straightforward implementations of learning algorithms. Mathematically, what is common to different sigmoid functions used by different researchers? We establish a common representation of inverse sigmoid functions in terms of the Guass Hypergeometric function, generalizing different node function formulations. We also show that the continuous Hopfield network equation can be transformed into a Legendre differential equation, without assuming the specific form of the node function; this establishes a link between Hopfield nets and the method of function approximation using Legendre polynomials

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A Generalization Of The Trie Data Structure, Richard H. Connelly, F. Lockwood Morris Feb 1993

A Generalization Of The Trie Data Structure, Richard H. Connelly, F. Lockwood Morris

Electrical Engineering and Computer Science - Technical Reports

Tries, a form of string-indexed look-up structure, are generalized to permit indexing by terms built according to an arbitrary signature. The construction is parametric with respect to the type of data to be stored as values; this is essential, because the recursion which defines tries appeals from one value type to others. "Trie" (for any fixed signature) is then a functor, and the corresponding look-up function is a natural isomorphism. The trie functor is in principle definable by the "initial fixed point" semantics of Smyth and Plotkin. We simplify the construction, however, by introducing the "category-cpo", a class of category …

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A Probabilistic Analysis Of A Locality Maintaining Load Balancing Algorithm, Kishan Mehrotra, Sanjay Ranka, Jhy-Chun Wang Jan 1993

A Probabilistic Analysis Of A Locality Maintaining Load Balancing Algorithm, Kishan Mehrotra, Sanjay Ranka, Jhy-Chun Wang

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

This paper presents a simple load balancing algorithm and its probabilistic analysis. Unlike most of the previous load balancing algorithms, this algorithm maintains locality. We show that the cost of this load balancing algorithm is small for practical situations and discuss some interesting applications for data remapping.

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Static And Runtime Scheduling Of Unstructured Communication, Sanjay Ranka, Jyu-Chun Wang Jan 1993

Static And Runtime Scheduling Of Unstructured Communication, Sanjay Ranka, Jyu-Chun Wang

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

With the advent of new routing methods, the distance to which a message is sent is becoming relatively less and less important. Thus assuming no link contention, permutation seems to be an efficient collective communication primitive. All-to-many communication is required for solving a large class of irregular and loosely synchronous problems on distributed memory MIMD machines. In this paper we present several algorithms for decomposing all-to-many personalized communication into a set of disjoint partial permutations. These partial permutations avoid node contention and/or link contention. We discuss several algorithms and study their effectiveness both from the view of static scheduling as …

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Solving The Region Growing Problem On The Connection Machine, Nawal Copty, Sanjay Ranka, Geoffrey C. Fox, Ravi Shankar Jan 1993

Solving The Region Growing Problem On The Connection Machine, Nawal Copty, Sanjay Ranka, Geoffrey C. Fox, Ravi Shankar

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

This paper presents a parallel algorithm for solving the region growing problem based on the split and merge approach. The algorithm was implemented on the CM-2 and the CM-5 in the data parallel and message passing models. The performance of these implementations is examined and compared.

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Architectural Support For High-Performance Distributed Computing, Jongbaek Park, Salim Hariri Jan 1993

Architectural Support For High-Performance Distributed Computing, Jongbaek Park, Salim Hariri

Electrical Engineering and Computer Science - All Scholarship

The emergence of high speed networks and the proliferation of high performance workstations have attracted a lot of interest in workstation-based distributed computing. Current trend in local area networks is toward higher communication bandwidth as we progress from Ethernet networks that operate at 10 Mbit/sec to higher speed networks that can operate in Gbit/sec range. Also, current workstations are capable of delivering tens and hundreds of Megaflops of computing power. By using a cluster of such high-performance workstations and the high-speed networks, a high-performance distributed computing environment could be built in cost-effective manner as an alternative of supercomputing platform. However, …

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Runtime Compilation Techniques For Data Partitioning And Communication Schedule Reuse, Ravi Ponnusamy, Joel Saltz, Alok Choudhary Jan 1993

Runtime Compilation Techniques For Data Partitioning And Communication Schedule Reuse, Ravi Ponnusamy, Joel Saltz, Alok Choudhary

Northeast Parallel Architecture Center

In this paper, we describe two new ideas by which HPF compiler can deal with irregular computations effectively. The first mechanism invokes a user specified mapping procedure via a set of compiler directives. The directives allow the user to use program arrays to describe graph connectivity, spatial location of army elements and computational load. The second is a simple conservative method that in many cases enables a compiler to recognize that it is possible to reuse previously computed results from inspectors (e.g. communication schedules, loop iteration partitions, information that associates off-processor data copies with on-processor buffer locations). We present performance …

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Fast Mapping And Remapping Algorithms For Irregular And Adaptive Problems, Chao Wei Ou, Sanjay Ranka, Geoffrey C. Fox Jan 1993

Fast Mapping And Remapping Algorithms For Irregular And Adaptive Problems, Chao Wei Ou, Sanjay Ranka, Geoffrey C. Fox

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

This paper describes the performance of locality-based mapping and remapping partitioners for unstructured grids. We show that the algorithm produces good mappings at a relatively low cost and can be easily parallelized. Further, the algorithm can provide remapping for incremental problems at a fraction of the total cost.

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