bluuebunny/crossref_metadata_2025_split huggingface dataset:
Memory management techniques for Time Warp on a distributed memory machine
Authors: Preiss Bruno R. , Loucks Wayne M. 
Published: January 2007

This paper examines memory management issues associated with Time Warp synchronized parallel simulation on distributed memory machines. The paper begins with a summary of the techniques which have been previously proposed for memory management on various parallel processor memory structures. It then concentrates the discussion on parallel simulation executing on a distributed memory computer—a system comprised of separate computers, interconnected by a communications network. An important characteristic of the software developed for such systems is the fact that the dynamic memory is allocated from a pool of memory that is shared by all of the processes at a given processor.
This paper presents a new memory management protocol, pruneback, which recovers space by discarding previous states. This is different from all previous schemes such as artificial rollback and cancelback which recover memory space by causing one or more logical processes to roll back to an earlier simulation time.
The paper includes an empirical study of a parallel simulation of a closed stochastic queueing network showing the relationship between simulation execution time and amount of memory available. The results indicate that using pruneback is significantly more effective than artificial rollback (adapted for a distributed memory computer) for this problem. In the study, varying the memory limits over a 2:1 range resulted in a 1:2 change in artificial rollback execution time and almost no change in pruneback execution time.
A case study in simulating PCS networks using Time Warp
Authors: Carothers Christopher D. , Fujimoto Richard M. , Lin Yi-Bing 
Published: January 2007

There has been rapid growth in the demand for mobile communications over the past few years. This has led to intensive research and development efforts for complex PCS (personal communication service) networks. Capacity planning and performance modeling is necessary to maintain a high quality of service to the mobile subscriber while minimizing cost to the PCS provider. The need for flexible analysis tools and the high computational requirements of large PCS network simulations make it an excellent candidate for parallel simulation.
Here, we describe our experiences in developing two PCS simulation models on a general purpose distributed simulation platform based on the Time Warp mechanism. These models utilize two widely used approaches to simulating PCS networks: (i) the call-initiated and (ii) the portable-initiated models. We discuss design decisions that were made in mapping these models to the Time Warp executive, and characterize the workloads resulting from these models in terms of factors such as communication locality and computation granularity. We then present performance measurements for their execution on a network of workstations. These measurements indicate that the call-initiated model generally outperforms the portable initiated model, but is not able to capture phenomenon such as the “busy line” effect. Moreover, these studies indicate that the high locality in large-scale PCS network simulations make them well-suited for execution on general purpose parallel and distributed simulation platforms.
Buffer management in shared-memory Time Warp systems
Authors: Fujimoto Richard M. , Panesar Kiran S. 
Published: January 2007

Mechanisms for managing message buffers in Time Warp parallel simulations executing on cache-coherent shared-memory multiprocessors are studied. Two simple buffer management strategies called the sender pool and receiver pool mechanisms are examined with respect to their efficiency, and in particular, their interaction with multiprocessor cache-coherence protocols. Measurements of implementations on a Kendall Square Research KSR-2 machine using both synthetic workloads and benchmark applications demonstrate that sender pools offer significant performance advantages over receiver pools. However, it is also observed that both schemes, especially the sender pool mechanism, are prone to severe performance degradations due to poor locality of reference in large simulations using substantial amounts of message buffer memory. A third strategy called the partitioned buffer pool approach is proposed that exploits the advantages of sender pools, but exhibits much better locality. Measurements of this approach indicate that the partitioned pool mechanism yields substantially better performance than both the sender and receiver pool schemes for large-scale, small-granularity parallel simulation applications.
The central conclusions from this study are: (1) buffer management strategies play an important role in determining the overall efficiency of multiprocessor-based parallel simulators, and (2) the partitioned buffer pool organization offers significantly better performance than the sender and receiver pool schemes. These studies demonstrate that poor performance may result if proper attention is not paid to realizing an efficient buffer management mechanism.
Manufacturing resource planning on a PC local area network
Authors: Kee H. Clark , Post Roy L. 
Published: January 2007

This paper details a large APL programming project of 12 man years. An integrated software system structured on the principles of MRP (manufacturing resource planning) was implemented by a Bristol-Myers in house team for use in a new manufacturing facility.
The system applies off-the-shelf technology in innovative ways, using STSC APL*PLUS/PC as the only programming language, to build a very sophisticated application on IBM/PCs fully sharing data in a secure environment via the NESTAR Plan 4000 local area network and file server.
The paper describes technical, application, and business aspects of the project. It should be of interest to (1) persons contemplating or involved in developing APL applications on a local area network, (2) persons developing or who want to develop an integrated manufacturing system, and (3) anyone interested in large APL applications.
The plant at which this system operates is located in Nijimegen, the Netherlands, and produces powdered infant formula and other nutritional beverages.
The authors believe that this paper is of value both in its description of technological hurdles and achievements, and in the details of the business application.
APL in quality business management
Authors: McKee Terence J. 
Published: January 2007

Companies monitor their processes so that they can identify actions that need to be taken. Measures such as monthly sales, expenses by category, inventory levels, days debt and computer service availability are recorded and reported.
This paper introduces the application of quality control techniques to help you determine whether a process needs intervention. You will want to identify when a short term fluctuation becomes significant, when a longer term trend appears and most important, determine what sort of action is appropriate.
There are many potential pitfalls in presentation techniques even when the correct information is being used. Some are mentioned, but are not the prime purpose of this paper. There are good examples in reference 1.
Integrating ordinary type and many languages with the APL alphabet and keyboard
Authors: Berry Paul 
Published: January 2007

To enjoy the advantages of APL, for too many years the APL user has had to forego “ordinary” characters and keyboards. This has been a major inconvenience to English-speaking North Americans, who have had to adjust to an unconventional keyboard and a character set without lower case, and even worse for Europeans, who found their national keyboards ignored and their national characters unrecognized.
With improvements in technology, a change of orientation is possible. Where formerly APL was conceived as a closed system, independent of everybody else's typography, now it is possible to integrate APL with each nation's standard keyboard. This paper proposes a return to conventional lowercase and caps for APL alphabetics, keyboards that offer APL characters without disturbing conventional layouts, and a major expansion of the APL character set to embrace the characters of a world-wide set of languages.
APLIM—applied linear interactive models
Authors: Ansell J. I. , Sykes A. M. 
Published: January 2007

Regression is the most frequently and widely applied technique in Statistics. The field of applications range from experimental design (historically in agriculture) to financial modelling. The technique has been greatly enhanced by the radical approach due to Nelder and Wedderburn. Their approach unified many apparently disparate applications of linear models to produce the Generalized Linear Model. Others have subsequently expanded their work. The paper briefly reviews this work indicating the main features which should be of interest to practitioners in many disciplines, e.g. education, sociology, medicine, economics, and the sciences.
The original software developed from this approach was written in FORTRAN which the present authors believe constrained the development of a truly interactive package. APLIM, the first commercial APL version of the Generalized Linear Model is described. Stress is placed on a “user friendly” approach throughout the package.
The authors have used APLIM to teach undergraduate students at the College Generalized Models, and a taste of their present teaching approach is given. The software has already been tested internally at the college by allowing other research workers access to it.
The authors are at present working on a version for the IBM PC, aided by IBM UK.
Modeling I/O subsystems (tutorial)
Authors: Buzen Jeffrey P. 
Published: January 2007

This tutorial will present techniques for modeling the performance of I/O subsystems that incorporate channels, control units, string controllers and direct access devices. The presentation will focus on the general principles involved in analyses of this type, and will explore the strengths and weaknesses of alternative assumptions. Attendees should gain an overall understanding of basic analysis procedures so they can deal with alternative I/O architectures that are not treated explicitly in the presentation.
The material in this tutorial is mathematically oriented, and attendees should have some familiarity with basic queueing theory. However, the presentation is almost entirely self contained, and all important concepts and equations will be fully explained. Operational analysis will be used throughout to simplify the derivation of major results and clarify the assumptions required at each stage.
Software reliability modeling (tutorial)
Authors: Goel Amrit L. 
Published: January 2007

There are a number of views as to what software reliability is and how it should be quantified. Some people believe that this measure should be binary in nature so that an imperfect program would have zero reliability while a perfect one would have a reliability value of one. This view parallels that of program proving whereby the program is either correct or incorrect. Others, however, feel that software reliability should be defined as the relative frequency of the times that the program works as intended by the user. This view is similar to that taken in testing where a percentage of the successful ewes is used as a measure of program quality. According to the latter viewpoint, software reliability is a probabilistic measure and can be defined as follows:
Let F be a class of faults, defined arbitrarily, and T be a measure of relevant time, the units of which are dictated by the application at hand. Then the reliability of the software package with respect to the class of faults F and with respect to the metric T, is the probability that no fault of the class occurs during the execution of the program for a prespecified period of relevant time.
A number of models have been proposed during the past fifteen years to estimate software reliability and several other performance measures. These are based mainly on the failure history of software and can be classified according to the nature of the failure process studied as indicated below.

Times Between Failures Models:
In this class of models the process under study is the time between failures. The most common approach is to assume that the time between, say, the (i-1)st and ith failures, follows a distribution whose parameters depend on the number of faults remaining in the program during this interval.

Failure Count Models:
The interest of this class of models is in the number of faults or failures in specified time intervals rather than in times between failures. The failure counts are assumed to follow a known stochastic process with a time dependent discrete or continuous failure rate.

Fault Seeding Models:
The basic approach in this class of models is to “seed” a known number of faults in a program which is assumed to have an unknown number of indigenous faults.

Input Domain Based Models:
The basic approach taken here is to generate a set of test cases from an input distribution which is assumed to be representative of the operational usage of the program. Because of the difficulty in obtaining this distribution, the input domain is partitioned into a set of equivalence classes, each of which is usually associated with a program path.

In this tutorial we discuss the key models from the above classes and the related issues of parametric estimation, unification of models, Bayesian interpretation, validation and comparison of models, and determination of optimum release time.
Expert systems for performance analysis (tutorial)
Authors: Artis H. Pat 
Published: January 2007

A great portion of the formal practice called computer performance evaluation is the application of rules of thumb and proceduralized analysis of model results, specific reports, and data elements based on the experience and knowledge of the practitioner. Expert systems provide a technique to support the analyst in such mundane analyses and allow them to study more complex problems that cannot easily be proceduralized. Rather than replacing performance analysts expert systems provide an opportunity to increase their productivity.
The tutorial focuses on a discussion of the fundamental building blocks of expert systems: vocabularies, rules, and policies. A familiar example is used to illustrate using expert systems for analysis of performance results.
Empirical results on locality in database referencing
Authors: Verkamo A. Inkeri 
Published: January 2007

Database referencing behaviour is analyzed with respect to locality features. The analysis is based on database reference strings collected from several runs of typical batch programs accessing a real database. Locality of reference is measured by the stack distance probability distribution, the number of block faults, and a locality measure based on the memory reservation size.
In all the experiments, locality of reference is observed, but it is found to be weaker than in code referencing or even in some previous studies on database referencing. The phase/transition concept used in virtual memory systems is not well applicable to database referencing, since a large part of the locality set is constantly changing. The disruption of the phases is predominantly due to random referencing of data blocks. The references to index blocks show stronger locality. In some special cases, sequentiality is observed in the use of the data blocks. In general, neither replacement strategies developed for virtual memory systems nor prefetching techniques seem adequate for performance improvement of database referencing.
An analytic model of the hyperchannel network using multiple channel architecture
Authors: Chlamtac I. , Eisinger M. 
Published: January 2007

The HYPERchannel communication network configured around one to four channels is considered. We develop a queueing model which characterizes the network performance as a function of the number of channels, the channel load and the number of stations in the network. The model is used to analyze the multichannel system performance and to evaluate the effect of the channel selection mechanism, as implemented by the HYPERchannel station interface units, on the performance.
It is shown that the network bandwidth utilization is directly related to the channel selection process and that it varies with network configuration and load. These observed relations are especially significant since they are most pronounced in networks with small number of stations, the typical configuration in the majority of operational HYPERchannel networks.
On the applicability of using multiprogramming level distributions
Authors: Dowdy Lawrence W. , Chopra Manvinder S. 
Published: January 2007

A computer system's workload is represented by its multiprogramming level, which is defined as the number of tasks (jobs, customers) which actively compete for resources within the system. In a product-form queuing network model of the system, the workload is modeled by assuming that the multiprogramming level is either fixed (i.e., closed model) or that the multiprogramming level depends upon an outside arrival process (i.e., open model). However, in many actual systems, closed and open models are both inappropriate since the multiprogramming level is neither fixed nor governed by an outside arrival process.
In an actual system., the multiprogramming level varies due to features such as task spawning, killing, blocking, parallel processing, and/or simultaneous resource possession. The multiprogramming level is a random variable with an associated distribution. This paper demonstrates that improved models can result from using this multiprogramming level distribution information. Several examples relative to open versus closed models, subsystem models, actual system models, and blocking models are given which demonstrate the applicability of using multiprogramming level distributions. This applicability, shown via the examples, is the main contribution of the paper. The examples also motivate interesting theoretical results relating to open models, closed models, and subsystem models.
APL2-a RISC business
Authors: Alfonseca M. , Selby D. 
Published: January 2007

APL2 is one of the most exciting programming languages to evolve from IBM's original APL discovery. APL2 has been restricted to IBM 370 mainframe computers, due to the complexity of the interpreter required to implement all facets of the language.
This paper describes a joint research / feasibility study carried out by IBM's Madrid and Winchester Scientific Centres on generating a “Portable” Workstation APL2 interpreter.
An interactive simulation modeling system: DYNAGRAPH for multi-period planning on an APL spreadsheet
Authors: Aonuma T. 
Published: January 2007

A Modeling System named DYNAGRAPH has been developed on the IBM 5550 Personal Computer with NEXUS 5500 Graphics to interactively build dynamic simulation models using APL functions. A model for the simulation is represented by APL expressions in the rows of an APL Spreadsheet. The modeling of dynamic systems is achieved by a state-variable method.
The paper introduces DYNAGRAPH and the underlying modeling method. Some of the modeling functions for dynamic simulations are presented. We claim that the method is suitable and convenient for modeling problems of moderate size, especially when using APL in teaching or business environments: DYNAGRAPH is useful as a training tool and an APL program generator to enhance APL applications in management science.
Application-sol interaction: an APL2 approach
Authors: Deerhake S. 
Published: January 2007

This paper describes an APL2 application programmer tool which simplifies the development and implementation of APL2 applications which interact with SQL. The described tool consists of a suite of APL2 functions which provide a high level, easy-to-use, application-SQL interface. The interface extends the SQL concepts of tables and operations on tables into the APL2 workspace, providing a simple method of interaction between APL2 applications and SQL. This approach also provides a great deal of isolation between the APL2 code and the SQL code required for manipulating the application's data.
Besides simplifying the usage of SQL within APL2 applications, the tool provides a convenient means for “tuning” an application's use of SQL, particularly the SQL SELECT statements used by the application. It also provides a framework for exploring extensions to SQL statements and syntax. While still somewhat experimental, the described tool has been effectively used by inexperienced APL2 programmers with virtually no knowledge of SQL.
APL graphics for learning mathematics
Authors: Kikkawa M. 
Published: January 2007

Since 1972, math-teachers at Shokei Jogakuin Senior High School have been using computers in their classes. In 1982, they changed from FORTRAN to APL, because APL had more possibilities for enriching math classes. At present, they are using APL Graphics to help students grasp abstract concepts in Mathematics.
This paper discusses the use of APL Graphics in the classroom by both teachers and students, and the evaluation of its value in teaching.
Achievement certificates from graphics environment
Authors: Olsen T. M. 
Published: January 2007

Karsten Manufacturing Corporation issues a “Certificate of Hole in One” (CHIO) to golfers who ace with PING (trademark) equipment. Formerly done manually, the certificate is now plotted automatically in less than two minutes, unattended, with two-color English Gothic and simplex italic Roman fonts, and a digitized signature, on gilded, preprinted, parchment forms. The plot file is produced from international input data received orally by telephone, or on tape from the “Golf Digest” clearing house. The APL2 application was implemented as an extension of the IBM GIAM graphics language and employs several new commands for loading and manipulating graphic characters from the Hershey font library. The paper explains various input panels and graphic displays. Technical obstacles including acceptable interactive and batch running-time-per-certificate are described, along with their solution. The method includes traditional MIS techniques and shows how these are applied in a production system.
This is the story of how the CHIO project evolved and how we learned by doing.
Iterative scaling of marks using APL-a case study
Authors: Petocz P. 
Published: January 2007

This paper presents a case study where APL was used successfully to tackle a problem that appeared to be quite complex. The work was carried out for the NSW Department of Technical and Further Education in 1985 and 1986, and is the subject of ongoing research at present.
A common problem in educational measurement is the comparison of scores obtained on different tests when the candidature for each test is not identical. Such a situation exists in NSW at the Higher School Certificate secondary school matriculation examinations. Different subjects attract candidatures of differing ability, yet it is important to calculate an aggregate mark as fairly as possible since it is used as a basis for selection into tertiary institutions. The iterative scaling procedure which has been used has been the subject of some controversy, caused in part by the fact that most people find it hard to understand exactly what is going on.
The Tertiary Preparation Certificate is a matriculation course offered by the NSW Department of TAFE and is designed to prepare mature-age students for tertiary study. The aggregate mark obtained in this course was required to be comparable to HSC aggregate marks, so the iterative scaling procedure was implemented using APL to process these marks.
The APL program has been used successfully during the previous two years on groups of up to 100 students. The algorithm is documented here for the first time in a form that is ready to be used by anyone with access to APL. There is discussion on the rationale and assumptions used in the calculations, and comments are made on the role that APL played in the whole process.