ppxscal/embedding_network huggingface dataset:
Accounting for Memory Bank Contention and Delay in High-Bandwidth Multiprocessors
Authors: Guy E. Blelloch, Phillip B. Gibbons, Yossi Matias, Marco Zagha
Venue: IEEE Transactions on Parallel and Distributed Systems (1997)

For years, the computation rate of processors has been much faster than the access rate of memory banks, and this divergence in speeds has been constantly increasing in recent years. As a result, several shared-memory multiprocessors consist of more memory banks than processors. The object of this paper is to provide a simple model (with only a few parameters) for the design and analysis of irregular parallel algorithms that will give a reasonable characterization of performance on such machines. For this purpose, we extend Valiant's bulk-synchronous parallel (BSP) model with two parameters: a parameter for memory bank delay, the minimum time for servicing requests at a bank, and a parameter for memory bank expansion, the ratio of the number of banks to the number of processors. We call this model the (d, x)-BSP. We show experimentally that the (d, x)-BSP captures the impact of bank contention and delay on the CRAY C90 and J90 for irregular access patterns, without modeling machine-specific details of these machines. The model has clarified the performance characteristics of several unstructured algorithms on the CRAY C90 and J90, and allowed us to explore tradeoffs and optimizations for these algorithms. In addition to modeling individual algorithms directly, we also consider the use of the (d, x)-BSP as a bridging model for emulating a very high-level abstract model, the Parallel Random Access Machine (PRAM). We provide matching upper and lower bounds for emulating the EREW and QRQW PRAMs on the (d, x)-BSP.
Automated test data generation using an iterative relaxation method
Authors: Neelam Gupta, Aditya P. Mathur, Mary Lou Soffa
Venue: Proceedings of the 6th ACM SIGSOFT international symposium on Foundations of software engineering (1998)

An important problem that arises in path oriented testing is the generation of test data that causes a program to follow a given path. In this paper, we present a novel program execution based approach using an iterative relaxation method to address the above problem. In this method, test data generation is initiated with an arbitrarily chosen input from a given domain. This input is then iteratively refined to obtain an input on which all the branch predicates on the given path evaluate to the desired outcome. In each iteration the program statements relevant to the evaluation of each branch predicate on the path are executed, and a set of linear constraints is derived. The constraints are then solved to obtain the increments for the input. These increments are added to the current input to obtain the input for the next iteration. The relaxation technique used in deriving the constraints provides feedback on the amount by which each input variable should be adjusted for the branches on the path to evaluate to the desired outcome.When the branch conditions on a path are linear functions of input variables, our technique either finds a solution for such paths in one iteration or it guarantees that the path is infeasible. In contrast, existing execution based approaches may require an unacceptably large number of iterations for relatively long paths because they consider only one input variable and one branch predicate at a time and use backtracking. When the branch conditions on a path are nonlinear functions of input variables, though it may take more then one iteration to derive a desired input, the set of constraints to be solved in each iteration is linear and is solved using Gaussian elimination. This makes our technique practical and suitable for automation.
A type-directed, on-line, partial evaluator for a polymorphic language
Authors: Tim Sheard
Venue: ACM SIGPLAN Notices (1997)

Recently, Olivier Danvy introduced a new, simple method for implementing powerful partial evaluators, namely type-directed partial evaluation[9]. He introduced a partial evaluator for the simply-typed lambda calculus ( sect;2). This paper explores the possibility of using the same techniques over a lambda calculus with a richer type system. We generalize and extend Danvy's work in four ways:1. Our system handles a much richer language than that presented by Danvy, including all of the features functional programmers have come to expect, such as polymorphism ( sect;5), inductive datatypes ( sect;10), and recursion ( sect;9).2. Our system includes a new systematic treatment of primitive operators ( sect;7) and the propagation of residualized code ( sect;7.1). This question has either been ignored or treated in an ad-hoc manner in previous work.3. Our system handles non-closed terms ( sect;6). This makes type-directed partial evaluation much more practically useful, and can easily be extended to work in languages with parameterized module systems.4. Our system makes the whole process more efficient, by using a lazy, on-demand implementation ( sect;8). The laziness of our implementation also causes the code produced to be more abstract and compact. Using this lazy implementation we have observed speedup ratios in the range 2--10, and code compactness improvements of more than 10 in some cases.All these extensions are made possible by a key technical innovation, namely, embedding types in values.
A joint authorisation scheme
Authors: Marie Rose Low, James A. Malcolm
Venue: ACM SIGOPS Operating Systems Review (1997)

There are many situations where more than one principal needs to give authorisation so that a single function can take place. Self-Authenticating Proxies provide a mechanism which may be suitably employed to support the requirements of joint authorisation.
GRGEC: computer algebra system for applications to gravity theory
Authors: S. I. Tertychniy, I. G. Obukhova
Venue: ACM SIGSAM Bulletin (1997)

We present a general outline of the specialized computer algebra system GRCEC intended for symbolic calculations in the field of the gravitation theory, the classical field theory on a curved background, and the adjacent methods belonging to the differential geometry. The distinctive features of the GRCEC input language are exhibited and the noteworthy elements of the system design are discussed.
Multithreading with Distributed Functional Units
Authors: Bernard K. Gunther
Venue: IEEE Transactions on Computers (1997)

Multithreaded processors multiplex the execution of a number of concurrent threads onto the hardware in order to hide latencies associated with memory access, synchronization, and arithmetic operations. Conventional multithreading aims to maximize throughput in a single instruction pipeline whose execution stages are served by a collection of centralized functional units. This paper examines a multithreaded microarchitecture where the heterogeneous functional unit set is expanded so that units may be distributed and partly shared across several instruction pipelines operating simultaneously, thereby allowing greater exploitation of interthread parallelism in improving utilization factors of costly resources. The multiple pipeline approach is studied specifically in the Concurro processor architecture¿a machine supporting multiple thread contexts and capable of context switching asynchronously in response to dynamic data and resource availability.Detailed simulations of Concurro processors indicate that instruction throughputs for programs accessing main memory directly can be scaled, without recompilation, from one to over eight instructions per cycle simply by varying the number of pipelines and functional units. In comparison with an equivalent coherent-cache, single-chip multiprocessor, Concurro offers marginally better performance at less than half of the estimated implementation cost. With suitable prefetching, multiple instruction caches can be avoided, and multithreading is shown to obviate the need for sophisticated instruction dispatch mechanisms on parallel workloads. Distribution of functional units results in a 150% improvement over the centralized approach in utilization factors of arithmetic units, and enables saturation of the most critical processor resources.
Analyzing stability in wide-area network performance
Authors: Hari Balakrishnan, Mark Stemm, Srinivasan Seshan, Randy H. Katz
Venue: Proceedings of the 1997 ACM SIGMETRICS international conference on Measurement and modeling of computer systems (1997)

The Internet is a very large scale, complex, dynamical system that is hard to model and analyze. In this paper, we develop and analyze statistical models for the observed end-to-end network performance based on extensive packet-level traces (consisting of approximately 1.5 billion packets) collected from the primary Web site for the Atlanta Summer Olympic Games in 1996. We find that observed mean throughputs for these transfers measured over 60 million complete connections vary widely as a function of end-host location and time of day, confirming that the Internet is characterized by a large degree of heterogeneity. Despite this heterogeneity, we find (using best-fit linear regression techniques) that we can express the throughput for Web transfers to most hosts as a random variable with a log-normal distribution. Then, using observed throughput as the control parameter, we attempt to quantify the spatial (statistical similarity across neighboring hosts) and temporal (persistence over time) stability of network performance. We find that Internet hosts that are close to each other often have almost identically distributed probability distributions of throughput. We also find that throughputs to individual hosts often do not change appreciably for several minutes. Overall, these results indicate that there is promise in protocol mechanisms that cache and share network characteristics both within a single host and amongst nearby hosts.
Trace-driven memory simulation: a survey
Authors: Richard A. Uhlig, Trevor N. Mudge
Venue: ACM Computing Surveys (CSUR) (1997)

As the gap between processor and memory speeds continues to widen, methods for evaluating memory system designs before they are implemented in hardware are becoming increasingly important. One such method, trace-driven memory simulation, has been the subject of intense interest among researchers and has, as a result, enjoyed rapid development and substantial improvements during the past decade. This article surveys and analyzes these developments by establishing criteria for evaluating trace-driven methods, and then applies these criteria to describe, categorize, and compare over 50 trace-driven simulation tools. We discuss the strengths and weaknesses of different approaches and show that no single method is best when all criteria, including accuracy, speed, memory, flexibility, portability, expense, and ease of use are considered. In a concluding section, we examine fundamental limitations to trace-driven simulation, and survey some recent developments in memory simulation that may overcome these bottlenecks.
Eliminating costly redundant computations from SQL trigger executions
Authors: François Llirbat, Françoise Fabret, Eric Simon
Venue: ACM SIGMOD Record (1997)

Active database systems are now in widespread use. The use of triggers in these systems, however, is difficult because of the complex interaction between triggers, transactions, and application programs. Repeated calculations of rules may incur costly redundant computations in rule conditions and actions. In this paper, we focus on active relational database systems supporting SQL triggers. In this context, we provide a powerful and complete solution to eliminate redundant computations of SQL triggers when they are costly. We define a model to describe programs, rules and their interactions. We provide algorithms to extract invariant subqueries from trigger's condition and action. We define heuristics to memorize the most &ldquo;profitable&rdquo; invariants. Finally, we develop a rewriting technique that enables to generate and execute the optimized code of SQL triggers.
Ethics, programming, and virtual environments
Authors: Michael E. Houle
Venue: Proceedings of the 2nd conference on Integrating technology into computer science education (1997)

We have devised a novel experiential approach to teaching students about the social impact of computers and the ethical, legal, and social responsibilities of computing professionals. Rather than teaching these topics in a traditional classroom manner, we teach them in a text-based online virtual educational environment. At the same time we use the environment's object-oriented design to instruct the students in object-oriented concepts, and to introduce them to software engineering by having them work in groups. The approach is proving extremely successful.
Optimal control dependence computation and the Roman chariots problem
Authors: Keshav Pingali, Gianfranco Bilardi
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1997)

The control dependence relation plays a fundamental role in program restructuring and optimization. The usual representation of this relation is the control dependence graph (CDG), but the size of the CDG can grow quadratically with the input programs, even for structured programs. In this article, we introduce the augmented postdominator tree (APT), a data structure which can be constructed in space and time proportional to the size of the program and which supports enumeration of a number of useful control dependence sets in time proportional to their size. Therefore, APT provides an optimal representation of control dependence. Specifically, the APT data structure supports enumeration of the set cd(e), which is the set of statements control dependent on control-flow edge e, of the set conds(w), which is the set of edges on which statement w is dependent, and of the set cdequiv(w), which is the set of statements having the same control dependences as w. Technically, APT can be viewed as a factored representation of the CDG where queries are processed using an approach known as filtering search.
Importance sampling for large ATM-type queueing networks
Authors: Pierre L'Ecuyer, Yanick Champoux
Venue: Proceedings of the 28th conference on Winter simulation (1996)

We estimate, by simulation, the cell-loss rate in an ATM switch modeled as a queueing network. Cell losses are rare events, so estimating their frequency by simulation is hard. We experiment with importance sampling as a mean of improving the simulation efficiency in that context.
The McCrimmon radical for identities of degree 3
Authors: Siamack Bondari, Irvin Roy Hentzel
Venue: ACM SIGSAM Bulletin (1997)

Suppose that R = (R, +, ) is a nonassociative ring, and that R+ = (R, +, circ;) is a Jordan ring where the circ;-product is defined by x circ; y = xy + yx. We compute the minimal degree three and degree four identities which are strong enough to make R third-power associative, R+ Jordan, and the McCrimmon radical of R+ to be an ideal of R. We display an absorption identity of R which demonstrates that the McCrimmon radical of R+ is an ideal of R. Because of the sizes of the matrices involved, the work was done modulo various primes and extrapolated to the rational numbers. The goal was to present the absorption identities. Actual proofs are too large to publish. The interested reader may check them using computer algebra packages. For (R+, +, circ;) to have a McCrimmon radical, we have to have characteristic ne; 2.The heart of the paper is a solution to the matrix equation AX = B where both the matrix A and the vector B have entries which are rational functions in alpha;. The solution proceeds by solving the system modulo various primes for various values of alpha; and using these residues to estimate the vector of rational functions X. A genetic algorithm is used to maximize the number of zero entries in the solution X.
Fast field solver-programs for thermal and electrostatic analysis of microsystem elements
Authors: Vladimir Székely, Márta Rencz
Venue: Proceedings of the 1997 IEEE/ACM international conference on Computer-aided design (1997)

To solve the problem of fast thermal and electrostatic simulation of microsystem elements two different field solver tools have been developed at TUB. The uS-THERMANAL program is capable for the fast steady state and dynamic simulation of suspended multi-layered microsystem structures, while the 2D-SUNRED program is the first version of a general field solver program, based on an original method, the Successive Network Reduction. This program offers a very fast and accurate substitute of FEM programs for the solution of the Poisson equation, e.g. solving a 32000 grid problem in about 6 minutes on a 586 PC. Application examples show the usability of the tools.
A Constant Time Optimal Parallel Algorithm for Two-Dimensional Pattern Matching
Authors: Maxime Crochemore, Leszek Gasieniec, Ramesh Hariharan, S. Muthukrishnan, Wojciech Rytter
Venue: SIAM Journal on Computing (1998)

We give an alphabet-independent deterministic parallel algorithm for finding all occurrences of a pattern array of size mh x mw in a text array of size nh x nw in the concurrent-read-concurrent-write--parallel-random-access-machine (CRCW--PRAM) model. Our algorithm runs in O(1) time performing optimal, that is, O(nh x nw) work, following preprocessing of the pattern. This improves the previous best bound of O(log log m ) time with optimal work [A. Amir, G. Benson, and M. Farach, Proceedings 5th Annual ACM Symposium on Parallel Algorithms and Architectures, ACM, New York, 1993, pp. 79--85], following preprocessing of the pattern, where m=max{mh, mw}.The preprocessing required by our algorithm (and that due to Amir, Benson, and Farach) can be accomplished in O(log log m) time and O(mh x mw) work [M. Crochemore et al., manuscript, 1993], [R. Cole et al., manuscript, 1993].
Exponential bounds with applications to call admission
Authors: Zhen Liu, Philippe Nain, Don Towsley
Venue: Journal of the ACM (JACM) (1997)

In this paper, we develop a framework for computing upper and lower bounds of an exponential form for a large class of single resource systems with Markov additive inputs. Specifically, the bounds are on quantities such as backlog, queue length, and response time. Explicit or computable expressions for our bounds are given in the context of queuing theory and numerical comparisons with other bounds and exact results are presented. The paper concludes with two applications to admission control in multimedia systems.
Automatic TCP buffer tuning
Authors: Jeffrey Semke, Jamshid Mahdavi, Matthew Mathis
Venue: ACM SIGCOMM Computer Communication Review (1998)

With the growth of high performance networking, a single host may have simultaneous connections that vary in bandwidth by as many as six orders of magnitude. We identify requirements for an automatically-tuning TCP to achieve maximum throughput across all connections simultaneously within the resource limits of the sender. Our auto-tuning TCP implementation makes use of several existing technologies and adds dynamically adjusting socket buffers to achieve maximum transfer rates on each connection without manual configuration.Our implementation involved slight modifications to a BSD-based socket interface and TCP stack. With these modifications, we achieved drastic improvements in performance over large bandwidth delay paths compared to the default system configuration, and significant reductions in memory usage compared to hand-tuned connections, allowing servers to support at least twice as many simultaneous connections.
Tasking solutions to the Sieve of Eratosthenes
Authors: W. Robert Collins
Venue: ACM SIGAda Ada Letters (1998)

Shapiro and later Bokhari described a multiprocessing view of the Sieve of Eratosthenes, to test load balancing on shared-memory multiprocessors. Shapiro proposed the following parallel version of the sieve:Eratosthenes starts off with a large number of slaves and instructs the first one to write down the integers 2, 3, 4, hellip; on the ground in a field. A second slave is dispatched with instructions to cross out all multiples of 2. Eratosthenes now moves down the "list" of numbers and dispatches a new slave whenever an uncrossed number is encountered. Thus, the third slave is sent off with instructions to cross out the multiples of 3, the fourth crosses out all multiples of 5, and so on. The uncrossed numbers that remain at the end of this process are the primes.It turns out that Ada (especially Ada95) supports multiprocessing well in the Sieve of Eratosthenes. One may make use of static and dynamic tasks, protected types, communication, and synchronization in a relatively small program, making the sieve an excellent choice for instruction. In a graduate course we offer at William amp; Mary, Theory of Programming Languages, we give students a multiprocessing assignment. At this stage, students have rarely done parallel programming, except for low-level threads and locks in operating systems courses. So a parallel programming assignment in a high level language adds an extra tool to their arsenals and gives them an idea of an important part of computing today.
Lyapunov Exponents for Finite State Nonlinear Filtering
Authors: Rami Atar, Ofer Zeitouni
Venue: SIAM Journal on Control and Optimization (1997)

Consider the Wonham optimal filtering problem for a finite state ergodic Markov process in both discrete and continuous time, and let $\sigma$ be the noise intensity for the observation. We examine the sensitivity of the solution with respect to the filter's initial conditions in terms of the gap between the first two Lyapunov exponents of the Zakai equation for the unnormalized conditional probability. This gap is studied in the limit as $\sigma\to 0$ by techniques involving considerations of nonlinear filtering and the stochastic Feynman--Kac formula. Conditions are given for the limit to be either negative or $-\infty$. Asymptotic bounds are derived in the latter case.
Block Triangular Decoupling for Linear Systems over Principal Ideal Domains
Authors: Naoharu Ito, Hiroshi Inaba
Venue: SIAM Journal on Control and Optimization (1997)

This paper studies in the framework of the so-called geometric approach the block triangular decoupling problem with state feedback for linear systems defined over a principal ideal domain with identity. First, various properties of feedback reachability submodules are discussed, and then under certain assumptions necessary and sufficient conditions for its solvability are obtained. Further, the pole assignability for decoupled systems is investigated. Finally, a simple example is given to illustrate the results.
Quickscreen
Authors: Timothy C. Hawkins, G. Frank Thompson
Venue: Proceedings of the 17th conference on Winter simulation (1985)

This paper describes a corps-level combat simulation developed by The BDM Corporation for the US ARMY. The simulation will be referred to here as Quickscreen, although its official Army designation is being changed to CORBAN (Corps Battle Analysis). Quickscreen can represent the activities of hundreds of individual units of battalion size and smaller in the context of a large-scale conflict and can treat all major elements of the AirLand Battle. Quickscreen was specifically designed to operate on a microcomputer and is currently operational on a Motorola-68000-based microcomputer system. The sophistication of Quickscreen's representation of command and control, and its ability to run on a microcomputer, put it on the cutting edge of combat simulation technology. Quickscreen has already seen extensive and significant application by the Army's Deep Attack Program Office.