Digital Commons Network^™

Disk-Directed I/O For An Out-Of-Core Computation, David Kotz

Computer Science Technical Reports

New file systems are critical to obtain good I/O performance on large multiprocessors. Several researchers have suggested the use of collective file-system operations, in which all processes in an application cooperate in each I/O request. Others have suggested that the traditional low-level interface (read, write, seek) be augmented with various higher-level requests (e.g., read matrix), allowing the programmer to express a complex transfer in a single (perhaps collective) request. Collective, high-level requests permit techniques like two-phase I/O and disk-directed I/O to significantly improve performance over traditional file systems and interfaces. Neither of these techniques have been tested on anything other …

Disk-Directed I/O For Mimd Multiprocessors, David Kotz

Dartmouth Scholarship

Many scientific applications that run on today's multiprocessors are bottlenecked by their file I/O needs. Even if the multiprocessor is configured with sufficient I/O hardware, the file-system software often fails to provide the available bandwidth to the application. Although libraries and improved file-system interfaces can make a significant improvement, we believe that fundamental changes are needed in the file-server software. We propose a new technique, \em disk-directed I/O, that flips the usual relationship between server and client to allow the disks (actually, disk servers) to determine the flow of data for maximum performance. Our simulations show that tremendous performance gains …

1.2, Yolanda Jones

E-lert

No abstract provided.

Parallel Algorithm Derivation And Program Transformation In A Preprocessing Compiler For Scientific Languages: The Psi Project And Hpf, L. R. Mullin, Thom Mcmahon

Computer Science Technical Reports

Scientific Programming and subsequent compilation is significantly complicated when programs are expected to perform on one or many processors for any size or dimensional problem. Scientific languages, although sophisticated and powerful, have been slow to evolve from their Von Neumann scalar by scalar operations to monolithic data parallel functions, e.g. Fortran 90/95. The structure of an array and corresponding architectural topology to which the arrays are mapped, may provide ways to increase portability and scalability of designs. This paper presents how the Psi(w) Calculus in conjunction with a useful algebra that provides convolutions, permutations, and scalar operations, is being used …

On Programming Scientific Applications In A Functional Language Extended By A \L' - Calculus Subsystem For Array Operations, L. R. Mullin, Werner Kluge

Computer Science Technical Reports

This paper discusses some of the pros and cons of extending functional languages by high-level array operations similar to those that are available in APL. This extension is based on the lp~calculus, an algebra of arrays which provides a small set of essential array operations defined in terms of dimensionalities, shapes and indexing functions. Since these operations specify context-free substitutions of array expressions by others, the lpcalculus fits perfectly into a functional programming paradigm.

In order to demonstrate the programming techniques made possible by the lp-calculus, we study a functional program for the approximation of numerical solutions of partial differential …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 11, Number 1, January 1995, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A fourteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

The Genus 22 Crossing Number Of K9, Adrian Riskin

Mathematics

Our main result is that a 1971 conjecture due to Paul Kainen is false. Kainen's conjecture implies that the genus 2 crossing number of K 9 is 3. We disprove the conjecture by showing that the actual value is 4. The method used is a new one in the study of crossing numbers, involving proof of the impossibility of certain genus 2 embeddings of Ks.

Many-To-Many Personalized Communication With Bounded Traffic, Sanjay Ranka, Ravi V. Shankar, Khaled A. Alsabti

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

This paper presents solutions for the problem of many-to-many personalized communication, with bounded incoming and outgoing traffic, on a distributed memory parallel machine. We present a two-stage algorithm that decomposes the many-to-many communication with possibly high variance in message size into two communications with low message size variance. The algorithm is deterministic and takes time 2tµ (+ lower order terms) when t >= O(p2; + p tau/µ). Here t is the maximum outgoing or incoming traffic at any processor, tau is the startup overhead and µ is the inverse of the data transfer rate. Optimality is achieved when the traffic …

Kripke Logical Relations And Pcf, Peter W. O'Hearn, John G. Riecke

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

Sieber has described a model of PCF consisting of continuous functions that are invariant under certain (finitary) logical relations, and shown that it is fully abstract for closed terms of up to third-order types. We show that one may achieve full abstraction at all types using a form of "Kripke logical relations" introduced by Jung and Tiuryn to characterize λ definability.

Objects, Interference, And The Yoneda Embedding, Peter W. O'Hearn, Uday S. Reddy

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

We present a new semantics for Algol-like languages that combines methods from two prior lines of development: [1] the object-based approach of [28,29], where the meaning of an imperative program is described in terms of sequences of observable actions, and [2] the functor-category approach initiated by Reynolds [31], where the varying nature of the run-time stack is explained using functors from a category of store shapes to a category of cpos. The semantics gives an account of both the phenomena of local state and irreversibility of state change. As an indication of the accuracy obtained, we present a full abstraction …

Syntactic Control Of Interference Revisited, Peter W. O'Hearn, A. J. Power, M. Takeyama, R. D. Tennent

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

In "Syntactic Control of Interference" (POPL, 1978), J. C. Reynolds proposes three design principles intended to constrain the scope of imperative state effects in Algol-like languages. The resulting linguistic framework seems to be a very satisfactory way of combining functional and imperative concepts, having the desirable attributes of both purely functional languages (such as pcf) and simple imperative languages (such as the language of while programs). However, Reynolds points out that the "obvious" syntax for interference control has the unfortunate property that fi-reductions do not always preserve typings. Reynolds has subsequently presented a solution to this problem (ICALP, 1989), but …

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

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

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 …

Run-Time Support For Parallelization Of Data-Parallel Applications On Adaptive And Nonuniform Computational Environments, Maher Kaddoura, Sanjay Ranka

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

In this paper we discuss the runtime support required for the parallelization of unstructured data parallel applications on nonuniform and adaptive environments. The approach presented is reasonably general and is applicable to a wide variety of regular as well as irregular applications. We present performance results for the solution of an unstructured mesh on a cluster of heterogeneous workstations.

Optimization Using Replicators, Anil Ravindran Menon, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka

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

Replicator systems are among the simplest complex systems and can be considered to be at the foundation of many popularly used models ranging from theories of evolution and neurobiology to sociobiology and ecology. This paper presents the first successful application 2 of replicators to optimization problems. For a graph bi-partitioning problem with 50,000 nodes and 300,000 edges, for instance, close to optimal solutions were obtained in a few hundred iterations. Replicators provide a potentially powerful new tool to solve other optimization problems as well.

Passion Runtime Library For The Intel Paragon, Alok Choudhary, Rajesh Bordawekar, Sachin More, K. Sivaram, Rajeev Thakur

Electrical Engineering and Computer Science - All Scholarship

We are developing a runtime library which provides a number of routines to perform the I/O required in parallel applications in an efficient and convenient manner. This is part of a project called PASSION, which aims to provide software support for high-performance parallel I/O at the compiler, runtime and file system levels. The PASSION Runtime Library uses a high-level interface which makes it easy for the user to specify the I/O required in the program. The user only needs to specify what portion of the data structure needs to read from or written to the file, and the PASSION routines …

A Simulation Model Of A Surveillance Radar Data Processing System Using Hi-Mass, Steven D. Farr, Alex F. Sisti, Douglas G. Fritz, Robert G. Sargent

Electrical Engineering and Computer Science - All Scholarship

This paper discusses the model specification, construction of the executable model, model execution, and the simulation results of a simulation model of a surveillance radar data processing system that was developed using the Hierarchical Modeling and Simulation System (HI-MASS). HI-MASS is an object oriented C++ based system that supports model specification (modeling) using the Hierarchical Control Flow Graph Model paradigm and executes simulation models using the sequential synchronous simulation execution algorithm. Models specified in this model paradigm use two complementary hierarchical specification structures, one to specify the model components and their interconnections and the other to specify the behaviors of …

Verification And Validation Of Simulation Models, Douglas G. Fritz, Robert G. Sargent, Thorsten Daum

Electrical Engineering and Computer Science - All Scholarship

The Hierarchical Modeling and Simulation System (HI-MASS) is a prototype modeling and simulation system that supports modeling based on the Hierarchical Control Flow Graph Model paradigm and simulation execution using a sequential synchronous simulation algorithm. The prototype is an object oriented C++ based system designed for a Unix environment and implemented using freely available software tools. Models are specified using two complementary hierarchical model specification structures, one to specify the components which comprise a model and how those components are interconnected, and the other to specify the behaviors of the individual components. A graphical user interface provides for component and …

Software Tool Evaluation Methodology, Salim Hariri, Sung Yong Park, Rajashekar Reddy, Mahesh Subramanyan

Northeast Parallel Architecture Center

The recent development of parallel and distributed computing software has introduced a variety of software tools that support several programming paradigms and languages. This variety of tools makes the selection of the best tool to run a given class of applications on a parallel or distributed system a non-trivial task that requires some investigation. We expect tool evaluation to receive more attention as the deployment and usage of distributed systems increases. In this paper, we present a multi-level evaluation methodology for parallel/distributed tools in which tools are evaluated from different perspectives. We apply our evaluation methodology to three message passing …

High Performance Fortran And Possible Extensions To Support Conjugate Gradient Algorithms, K. Dincer, Ken Hawick, Alok Choudhary, Geoffrey C. Fox

Northeast Parallel Architecture Center

We evaluate the High-Performance Fortran (HPF) language for the compact expression and efficient implementation of conjugate gradient iterative matrix-solvers on High Performance Computing and Communications(HPCC) platforms. We discuss the use of intrinsic functions, data distribution directives and explicitly parallel constructs to optimize performance by minimizing communications requirements in a portable manner. We focus on implementations using the existing HPF definitions but also discuss issues arising that may influence a revised definition for HPF-2. Some of the codes discussed are available on the World Wide Web at http://www.npac.syr.edu/hpfa/ alongwith other educational and discussion material related to applications in HPF.

Supporting Irregular Distributions Using Data-Parallel Languages, Ravi Ponnusamy, Yuan-Shin Hwang, Raja Das, Alok Choudhary, Geoffrey Fox

Northeast Parallel Architecture Center

Languages such as Fortran D provide irregular distribution schemes that can efficiently support irregular problems. Irregular distributions can also be emulated in HPF. Compilers can incorporate runtime procedures to automatically support these distributions.

Approximation Algorithms: Good Solutions To Hard Problems, Ran Libeskind-Hadas

All HMC Faculty Publications and Research

Consider a computer network represented by an undirected graph where the vertices represent computer nodes and the edges represent links between the nodes. Since some of the links in the network may become faulty, link testing devices are placed at some of the nodes. A tester at a particular node can test all links incident to that node. Since the testers are expensive, however, we wish to deploy the minimum number of these devices such that every link is incidient to at least one node containing a tester. In graph theoretic terms, a vertex cover is a subset of the …

A Multithreaded Message Passing Environment For Atm Lan/Wan, Rajesh Yadav, Rajashekar Reddy, Salim Hariri, Geoffrey C. Fox

Northeast Parallel Architecture Center

Large scale High Performance Computing and Communication (HPCC) applications (e.g. Video-on-Demand, and HPDC) would require storage and processing capabilities which are beyond existing single computer systems. The current advances in networking technology (e.g. ATM) have made high performance network computing an attractive computing environment for such applications. However, using only high speed network is not sufficient to achieve high performance distributed computing environment unless some hardware and software problems have been resolved. These problems include the limited communication bandwidth available to the application, high overhead associated with context switching, redundant data copying during protocol processing and lack of support to …

A Knowledge-Based Approach To Class Scheduling, Mara Zell

Honors Theses, 1963-2015

A class scheduling application was developed to assist department chairs in producing class schedules each semester. This was accomplished using a knowledge-based system. The system utilized the many constraints involved in the class scheduling process to solve the problem. This application was developed and implemented in an object oriented package called Powerbuilder. Thus, the application is windows based with point and click features. Three trial schedules were produced. These results demonstrate the ability of the application to schedule three types of classes: classes without labs, classes with one lab, and classes with two labs. The end result is that an …

Liability Issues In The Development Of Electronic Chart Display Information Systems, Daniel R. Martin

Marine Affairs Theses and Major Papers

The Electronic Chart Display Information System (ECDIS) is a new and evolving aid to navigation. Proponents claim ECDIS will help navigators to synthesize previously disparate information and result in safer navigation. The technology to implement ECDIS already exists; the major hurdle the maritime community faces is the legal uncertainties associated with ECDIS. This paper investigates the potential legal impact ECDIS would have on the government, shipowners, mariners, and manufacturers, and evaluates current international efforts to promote ECDIS. Through a detailed analysis of admiralty and aeronautical case history, it is evident that; 1) generation of electronic nautical charts can post a …

An Evaluation Of Design Tradeoffs In A High Performance Media-On-Demand Server, Divyesh Jadav, Chutimet Srinilta, Alok Choudhary, P. B. Berra

Electrical Engineering and Computer Science - All Scholarship

One of the key components of a multi-user multimedia-on-demand system is the data server. Digitalization of traditionally analog data such as video and audio, and the feasibility of obtaining network bandwidths above the gigabit-per-second range are two important advances that have made possible the realization, in the near future, of interactive distributed multimedia systems. Secondary-to-main memory I/O technology has not kept pace with advances in networking, main memory and CPU processing power. Consequently, the performance of the server has a direct bearing on the overall performance of such a system. In this paper we present a high-performance solution to the …

National Hpcc Software Exchange, Shirley Browne, Jack Dongarra, Stan Green, Keith Moore, Tom Rowan, Reed Wade, Geoffrey .. Fox, Ken Hawick

Electrical Engineering and Computer Science - All Scholarship

This report describes an effort to construct a National HPCC Software Exchange (NHSE). This system shows how the evolving National Information Infrastructure (NII) can be used to facilitate sharing of software and information among members of the High Performance Computing and Communications (HPCC) community. To access the system use the URL: http://www.netlib.org/nse/.

Note On Algol And Conservatively Extending Functional Programming, Peter W. O'Hearn

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

A simple Idealized Algol is considered, based on Reynolds's "essence of Algol." It is shown that observational equivalence in this language conservatively extends observational equivalence in its assignment-free functional sublanguage.

Mapping Unstructured Computational Graphs For Adaptive And Nonuniform Computational Environments, Maher Kaddoura, Chao Wei Ou, Sanjay Ranka

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

In this paper we study the problem of mapping a large class of irregular and loosely synchronous data-parallel applications in a nonuniform and adaptive computational environment. The computational structure of these applications can be described in terms of a computational graph, where nodes of the graph represent computational tasks and edges describe the communication between tasks. Parallelization of these applications on nonuniform computational environments requires partitioning the graph among the processors in such fashion that the computation load on each node is proportional to its computational power, while communication is minimized. We discuss the applicability of current methods for graph …

The Expressiveness Of Locally Stratified Programs, Howard A. Blair, Wiktor Marek, John S. Schlipf

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

This paper completes an investigation of the logical expressibility of finite, locally stratified, general logic programs. We show that every hyperarithmetic set can be defined by a suitably chosen locally stratified logic program (as a set of values of a predicate over its perfect model). This is an optimal result, since the perfect model of a locally stratified program is itself an implicitly definable hyperarithmetic set (under a recursive coding of the Herbrand base); hence to obtain all hyperarithmetic sets requires something new, in this case selecting one predicate from the model. We find that the expressive power of programs …

Irregular Personalized Communication On Distributed Memory Machines, Sanjay Ranka, Jhy-Chun Wang

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

In this paper we present several algorithms for performing all-to-many personalized communication on distributed memory parallel machines. We assume that each processor sends a different message (of potentially different size) to a subset of all the processors involved in the collective communication. The algorithms are based on decomposing the communication matrix into a set of partial permutations. We study the effectiveness of our algorithms both from the view of static scheduling and from runtime scheduling.