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IBM Journal of Research and Development

Issue 6 • Date Nov. 1981

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Displaying Results 1 - 15 of 15
  • Design of Experiments in Computer Performance Evaluation

    Publication Year: 1981 , Page(s): 848 - 859
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1008 KB)  

    Techniques of statistical design of experiments have been successfully employed for many decades in a variety of applications in industry, agriculture, medicine, psychology, and other physical and social sciences. Their aim is to provide scientific and efficient means of studying the effects, on one or more variables of interest, of varying multiple controllable factors in an experiment. These techniques have not been widely used in the study of computer systems, although they can potentially have as large an impact as they have had in other fields. The purpose of this paper is to review some of the basic concepts underlying the statistical design and analysis of experiments and to illustrate them by means of examples drawn from studies of computer system performance. The examples include comparisons of alternate page replacement and free storage management algorithms, optimization of a scheduler, and validation of a system simulation model. View full abstract»

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  • Adaptive Spectral Methods for Simulation Output Analysis

    Publication Year: 1981 , Page(s): 860 - 876
    Cited by:  Papers (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1053 KB)  

    This paper addresses two central problems in simulation methodology: the generation of confidence intervals for the steady state means of the output sequences and the sequential use of these confidence intervals to control the run length. The variance of the sample mean of a covariance stationary process is given approximately by p(0)/N, where p(f) is the spectral density at frequency f and N is the sample size. In an earlier paper we developed a method of confidence interval generation based on the estimation of p(0) through the least squares fit of a quadratic to the logarithm of the periodogram. This method was applied in a run length control procedure to a sequence of batched means. As the run length increased the batch means were rebatched into larger batch sizes so as to limit storage requirements. In this rebatching the shape of the spectral density changes, gradually becoming flat as N increases. Quadratics were chosen as a compromise between small sample bias and large sample stability. In this paper we consider smoothing techniques which adapt to the changing spectral shape in an attempt to improve both the small and large sample behavior of the method. The techniques considered are polynomial smoothing with the degree selected sequentially using standard regression statistics, polynomial smoothing with the degree selected by cross validation, and smoothing splines with the amount of smoothing determined by cross validation. These techniques were empirically evaluated both for fixed sample sizes and when incorporated into the sequential run length control procedure. For fixed sample sizes they did not improve the small sample behavior and only marginally improved the large sample behavior when compared with the quadratic method. Their performance in the sequential procedure was unsatisfactory. Hence, the straightforward quadratic technique recommended in the earlier paper is still recommended as an effective, practical technique for simulation confidence i- nterval generation and run length control. View full abstract»

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  • The Software-Cache Connection

    Publication Year: 1981 , Page(s): 877 - 893
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1208 KB)  

    This paper describes an adaptation of standard Fourier analysis techniques to the study of software-cache interactions. The cache is viewed as a “black box” Boolean signal generator, where “ones” correspond to cache misses and “zeros” correspond to cache hits. The spectrum of this time sequence is used to study the dynamic characteristics of complex systems and workloads with minimal a priori knowledge of their internal organization. Line spectra identify tight loops accessing regular data structures, while the overall spectral density reveals the general structure of instruction localities. View full abstract»

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  • Approximate Solution of Queueing Networks with Simultaneous Resource Possession

    Publication Year: 1981 , Page(s): 894 - 903
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (799 KB)  

    Queueing networks are important as performance models of computer and communication systems because the performance of these systems is usually principally affected by contention for resources. Exact numerical solution of a queueing network is usually only feasible if the network has a product form solution in the sense of Jackson. An important network characteristic which apparently precludes a product form solution is simultaneous resource possession, e.g., a job holds memory and processor simultaneously. This paper extends previous methods for approximate numerical solution of queueing networks with homogeneous jobs and simultaneous resource possession to networks with heterogeneous jobs and simultaneous resource possession. View full abstract»

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  • Collision-Free Local Area Bus Network Performance Analysis

    Publication Year: 1981 , Page(s): 904 - 914
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (931 KB)  

    This paper deals with port access control for local area computer communication bus networks. Emphasizing properties of the algorithms and delay-throughput performance, we focus on two collision-free access control schemes recently proposed by Eswaran, Hamacher, and Shedler. We also provide a comparison of these schemes to other available bus access techniques. The performance analysis is based on representation of the bus network as a closed queueing system with nonpreemptive priority service. View full abstract»

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  • Delay Analysis of a Two-Queue, Nonuniform Message Channel

    Publication Year: 1981 , Page(s): 915 - 929
    Cited by:  Patents (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1017 KB)  

    A Message Channel is defined as a tandem connection of single server queues in which the successive service times experienced by any particular customer are scaled versions of the same random variable, and thus it serves as a model for sparsely connected store-and-forward data communications networks (or network segments) where messages typically preserve their lengths as they traverse the system. A particular instance of such a nonstandard queueing model is analyzed in this paper. The system consists of two single server queues in tandem subject to a Poisson arrival process (at the first queue) and providing service according to scaled versions of a sequence of two-level, discrete random variables. A set of recursive equations that can be used to solve the model for any given scaling factor at the second queue (normalized with respect to the first queue service) is explicitly derived. In addition, complete solutions are displayed for several cases of interest, and the equilibrium mean cumulative waiting times for these instances are compared as a method of indicating the impact of the scaling factor on the operation of the system. The extension of several results to systems with more general service time processes is discussed. View full abstract»

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  • Message Reassembly Times in a Packet Network

    Publication Year: 1981 , Page(s): 930 - 933
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (315 KB)  

    This paper addresses the problem of computing the reassembly time of a multipacket message. All packets from a single message are assumed to flow in sequence along the same physical path. The analysis includes the effects of contention between messages in the network on the delay time at each station along the path and its impact on message reassembly time. View full abstract»

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  • Fleshing Out Projections

    Publication Year: 1981 , Page(s): 934 - 954
    Cited by:  Papers (21)  |  Patents (16)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1636 KB)  

    In an earlier paper, the authors presented an algorithm for finding all polyhedral solid objects with a given set of vertices and straight line edges (its wire frame). This paper extends the Wire Frame algorithm to find all solid polyhedral objects with a given set of two dimensional projections. These projections may contain depth information in the form of dashed and solid lines, may represent cross sections, and may be overall or detail views. The choice of labeling conventions in the projections determines the difficulty of the problem. It is shown that with certain conventions and projections the problem of fleshing out projections essentially reduces to the problem of fleshing out wire frames. Even if no labeling is used, the Projections algorithm presented here finds all solutions even though it is possible to construct simple examples with a very large number of solutions. Such examples have a large amount of symmetry and various accidental coincidences which typically do not occur in objects of practical interest. Because of its generality, the algorithm can handle pathological cases if they arise. This Projections algorithm, which has applications in the conversion of engineering drawings in a Computer Aided Design, Computer Aided Manufacturing (CADCAM) system, has been implemented. The algorithm has successfully found solutions to problems that are rather complex in terms of either the number of possible solutions or the inherent complexity of projections of objects of engineering interest. View full abstract»

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  • An Emulation System for Programmable Sensory Robots

    Publication Year: 1981 , Page(s): 955 - 962
    Cited by:  Papers (16)  |  Patents (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    This paper describes EMULA, an experimental interactive system for the emulation of sensory robots. EMULA was constructed as a bridge between an existing language for driving actual robots and an existing geometric modeling system. The modeling system was extended to handle mechanisms, such as robots, and an emulation language was introduced to indicate certain specific physical effects, including sensory feedback, grasping and releasing of parts, and gravity. EMULA allows manipulation programs to be tested by users in interactive terminal sessions or in batch mode. Monitoring functions are provided to record actions, store selected views, and check for collisions. View full abstract»

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  • Impact of a Liquid Drop Against a Flat Surface

    Publication Year: 1981 , Page(s): 963 - 971
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (634 KB)  

    Lagrangian methods are used with an assumed flow field and a truncated sphere model to analyze the dynamical process of a liquid drop impacting a flat, rigid surface. The resulting differential equation for drop height as a function of time during contact is solved numerically for several values of the three parameters: Weber number of the incoming drop, ratio of the surface tension in air to that at the contact surface, and the viscosity parameter. The drop contact radius as a function of time is also calculated and compared with some experimental results in the literature. View full abstract»

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  • Recent Papers by IBM Authors

    Publication Year: 1981 , Page(s): 972 - 979
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (666 KB)  

    Reprints of the papers listed here may usually be obtained by writing directly to the authors. The authors' IBM divisions or groups are identified as follows: CHQ is Corporate Headquarters; DPD, Data Processing Division; DPMG, Data Processing Marketing Group; DPPG, Data Processing Product Group; DSD, Data Systems Division; FED Field Engineering Division; FSD, Federal Systems Division; GBG, General Business Group; GBG/I, General Business Group/International; GPD, General Products Division; GSD, General Systems Division; GTD, General Technology Division; IRD, Information Records Division; ISD, Information Systems Division; OPD, Office Products Division; RES, Research Division; SCD, System Communications Division; SPD, System Products Division; and SRI, Systems Research Institute. Journals are listed alphabetically by title; papers are listed sequentially for each journal View full abstract»

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  • Recent IBM patents

    Publication Year: 1981 , Page(s): 980 - 983
    Save to Project icon | PDF file iconPDF (307 KB)  
    Freely Available from IEEE
  • Authors

    Publication Year: 1981 , Page(s): 984 - 986
    Save to Project icon | PDF file iconPDF (303 KB)  
    Freely Available from IEEE
  • Author Index for Papers in Volume 25

    Publication Year: 1981 , Page(s): 987 - 990
    Save to Project icon | PDF file iconPDF (260 KB)  
    Freely Available from IEEE
  • Subject Index for Papers in Volume 25

    Publication Year: 1981 , Page(s): 991 - 994
    Save to Project icon | PDF file iconPDF (263 KB)  
    Freely Available from IEEE

Aims & Scope

The IBM Journal of Research and Development is a peer-reviewed technical journal, published bimonthly, which features the work of authors in the science, technology and engineering of information systems.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Clifford A. Pickover
IBM T. J. Watson Research Center