ppxscal/embedding_network huggingface dataset:
Optimization Techniques in Computer System Design \& Load Control
Authors: Prem S Sinha
Venue:  (1981)

Analytic modelling has proven to be cost-effective in the performance evaluation of computer systems. So far, queueing theory has been employed as the main tool. This thesis extends the scope of analytic modelling by using optimization techniques along with queuing theory in solving the decision-making problems of performance evaluation. Two different problems have been attempted in this thesis. .br First, a queueing network model is developed to find the optimal capacities and speeds of the memory levels in a memory hierarchy system operating in a multiprogrammed environment. Optimality is defined with respect to mean system response time under a fixed cost constraint. It is assumed that the number of levels in the hierarchy as well as the capacity of the lowest level are known. The effect of storage management strategy and program behaviour are characterised by the miss ratio function which, together with the device technology cost function, is assumed to be represented by power functions. It is shown that the solution obtained is globally optimal. .br Next, two adaptive schemes, SELF and MULTI-SELF, are developed to control the flow of jobs in a multiprogrammed computer system. They periodically determine the number of jobs from each class that should be activated to minimize the mean system residence time without saturating the system. The computation is based on the estimated system workload in the next interval. An exponential smoothing technique is used to reduce the error in estimating the values of the model parameters. The service provided to each class (specifically, the mean response time) may be adjusted by changing the weight associated with the job class. From our simulation results, the schemes appear to be both stable and robust. Performance improvement over $S and the Knee criteria) is significant under some workloads. The overhead involved in its implementation is acceptable and the error due to some of the assumptions in the formulation and solution of the model are discussed.
WWW Proxy Traffic Characterization with Application to Caching
Authors: Abdulla Ghaleb, Fox Edward A., Abrams Marc, Williams Stephen
Venue:  (1997)

Characterizing World Wide Web proxy traffic helps identify parameters that affect caching, capacity planning and simulation studies. In this paper we identify invariants that hold across a collection of ten traces representing traffic seen by caching-proxy servers. The traces were collected from governmental, industry, university, high school, and an online service provider environment, with request rates that range from a few accesses to millions of accesses per hour. We also show that the examined traffic is semi-similar. We explore sources of Web self-similarity and we conclude that a strong source is the periodicity in the users behavior. The tests revealed that there is a strong connection between access rate from hour to hour. We also report the hit rate and weighted hit rate obtained by running a trace driven simulation on the workloads to simulate a proxy with infinite cache, similarly, accesses to unique servers and URLs are a small portion of the total. By considering these characteristics of traffic we can improve the utility of caching for WWW clients.
Semantik-basiertes Program-Slicing fuer Sprachen mit komplexenKontrollstrukturen
Authors: Zafer Oeztuerk
Venue:  (1995)

Semantik-basierte Program-Slicer wurden anfangs der 90er Jahre fuer einfache WHILE-Sprachen mit Hilfe der denotationellen Semantik beschrieben. Um das Program-Slicing auch fuer Sprachen mit Spruengen und Prozeduren beschreiben zu koennen, muss besonders der Kontrollfluss innerhalb des Programms in geeigneter Weise repraesentiert werden. Damit der Program-Slicer trotzdem mit Hilfe der denotationellen Semantik beschrieben werden kann, verwenden wir die Continuation-Semantics.
GASP-II: A Geometric Algorithm Animation System for an Electronic Classroom
Authors: M. Shneerson, A. Tal
Venue:  (1996)

This paper describes GASP-II, an algorithm animation system for geometric computing. Because views of the same running algorithm may reside on different machines, GASP-II is particularly suitable for an electronic classroom. End-user may choose to use different views of the same running algorithm, allowing each student to study the algorithm in the most appropriate way. Moreover, end-users can run the animation in different speeds, and focus on the parts of the algorithm which they find difficult. Limiting the domain to computational geometry makes it possible to automate large parts of the process of creating an animation and the programmer can choose to be isolate from any concern about how graphics is done. Finally, GASP-II provides a visual debugging facility for geometric computing.
Steady Viscous Flow in a Triangular Cavity
Authors: Calvin J. Ribbens, Layne T. Watson, C. Y. Wang
Venue:  (1992)

Steady recirculating viscous flow inside an equilateral triangular cavity is generated by translating one side. The Navier-Stokes equations are solved numerically using finite difference on a transformed geometry. The results show a primary eddy and a series of secondary eddies at the stagnant corner. For high Reynolds numbers the interior of the primary eddy has constant vorticity, but its value cannot be predicted by the mean-squared law.
A New View on What Limits TCP/IP Throughput in Local Area Networks
Authors: Marc Abrams, Qi Chen
Venue:  (1991)

This paper presents experimental results on what limits local area network throughput at the application program level for two popular transport protocols, TCP and UDP, using two application program interfaces, Berkeley sockets and System V transport layer interface. The sensitivity of application-level performance to the choice of host computer speed and background load on the host are also studied. Two sets of measurements are discussed. The first contains macroscopic measurement of throughput on 68020, 68030, 68040, 80386, SPARC, and MIPS R2000 and R3000 based computers over a single Ethernet subnet. The second presents a detailed timing analysis using a hardware monitor of a TCP/IP implementation for PC architecture computers. Previous studies implicate memory copying, checksumming, and the operating system interface as the major overheads in TCP/IP, rather than the time required to execute the protocol itself. This study indicates that these factors are secondary when the sender and receiver are closely matched in speed; rather the primary bottleneck is the TCP flow control mechanism. TCP flow control becomes closer to optimal as the degree of speed mismatch increases. We draw conclusions on why window mechanisms should be augmented by rate based flow control in the new generation of high data rate networks.
Predicting Region Branches Using Predicate Update Branch Prediction
Authors: Beth Simon, Brad Calder, Jeanne Ferrante
Venue:  (2001)

Predicated Execution can be used to alleviate the costs associated with frequently mispredicted branches. This is accomplished by trading the cost of a mispredicted branch for execution of both paths following the conditional branch. In this paper we concentrate on using predicated execution to aggressively reduce a program''s branch misprediction rate. We examine an aggressive region formation algorithm focused on removing hard-to-predict branches. This region formation algorithm allows the inclusion of unbiased, but predictable, branches within a region. This was essential in order to predicate the hard-to-predict branches for the programs we examined. The branches left in the predicated region will now need to be predicted during fetch with greater frequency. Using a traditional branch prediction architecture, these region-based branches can end up having a similar miss rate to the hard-to-predict branches that were removed. We propose the Predicate Update Branch Predictor architecture to aid the prediction of these region-based branches. Region-based branches are heavily correlated with the outcome of the predicate with which they are guarded. A branch predicated on false should always predict that the branch should not be taken. Our predicate update predictor updates the global history with the result of the predicate defining instruction. This allows the region branches guarded by those predicates to benefit from this correlation history when making their prediction. For codes predicated with our hard-to-predict region formation algorithm, our results show that a Predicate Update Branch Predictor reduces the mispredict rate from an average of 7% to 5% for the benchmarks we studied.
A Foundation for the Design and Analysis of Robotic Systems and Behaviors
Authors: Zhang Ying
Venue:  (1994)

Robots are generally composed of electromechanical parts with multiple sensors and actuators. The overall behavior of a robot emerges from coordination among its various parts and interaction with its environment. Developing intelligent, reliable, robust and safe robots, or real-time embedded systems, has become a focus of interest in recent years. In this thesis, we establish a foundation for modeling, specifying and verifying discrete/continuous hybrid systems and take an integrated approach to the design and analysis of robotic systems and behaviors. A robotic system in general is a hybrid dynamic system, consisting of continuous, discrete and event-driven components. We develop a semantic model for dynamic systems, that we call Constraint Nets (CN). CN introduces an abstraction and a unitary framework to model discrete/continuous hybrid systems. CN provides aggregation operators to model a complex system hierarchically. CN supports multiple levels of abstraction, based on abstract algebra and topology, to model and analyze a system at different levels of detail. CN, because of its rigorous foundation, can be used to define programming semantics of real-time languages for control systems. While modeling focuses on the underlying structure of a system --- the organization and coordination of its components --- requirements specification imposes global constraints on a system''s behavior, and behavior verification ensures the correctness of the behavior with respect to its requirements specification. We develop a timed linear temporal logic and timed $\forall$-automata to specify timed as well as sequential behaviors. We develop a formal verification method for timed $\forall$-automata specification, by combining a generalized model checking technique for automata with a generalized stability analysis method for dynamic systems. A good design methodology can simplify the verification of a robotic system. We develop a systematic approach to control synthesis from requirements specification, by exploring a relation between constraint satisfaction and dynamic systems using constraint methods. With this approach, control synthesis and behavior verification are coupled through requirements specification. To model, synthesize, simulate, and understand various robotic systems we have studied in this research, we develop a visual programming and simulation environment that we call ALERT: A Laboratory for Embedded Real-Time systems.
SAM: SEQUENCE ALIGNMENT AND MODELING SOFTWARE SYSTEM
Authors: Richard Hughey, Anders Krogh
Venue:  (1995)

The Sequence Alignment and Modeling system (SAM) is a collection of flexible software tools for creating, refining, and using linear hidden Markov models for biological sequence analysis. The model states can be viewed as representing the sequence of columns in a multiple sequence alignment, with provisions for arbitrary position-dependent insertions and deletions in each sequence. The models are trained on a family of protein or nucleic acid sequences using an expectation-maximization algorithm and a variety of algorithmic heuristics. A trained model can then be used to both generate multiple alignments and search databases for new members of the family. SAM is written in the C programming language for Unix machines and MasPar parallel computers, and includes extensive documentation. The algorithms and methods used by SAM have been described in several pioneering papers from the University of California, Santa Cruz. These papers, as well as the SAM software suite, are available via anonymous ftp to ftp.cse.ucsc.edu in the pub/protein directory, or via the World-Wide Web to http://www.cse.ucsc.edu/research/compbio/.
JavaBeans as a Framework for Collaborative Software
Authors: Begole James "Bo", Isenhour Philip L., Shaffer Clifford A.
Venue:  (1998)

We describe the use of a popular component framework, JavaBeans, to facilitate developing collaborative software. We describe the class of collaboration-unaware components that can be effectively shared under this framework, and an extension that supports development of efficient collaboration-aware components.
AN IMPLEMENTATION OF THE KEY REACTION APPROACH INCOMPUTER CHEMICAL SYNTHESIS (M.S. Thesis)
Authors: Esther H. Lum
Venue:  (1990)

This thesis identifies one search strategy taken by organic chemists, the key reaction approach, and describes its simulation using the AI technique known as means-ends analysis. Given a target molecule, Synit, the system implementing the key reaction approach, chooses a starting material, determines what the ideal reaction would be, and selects the key reaction that most closely matches the ideal from a database of reactions. The key reaction is used to create an intermediate reaction step; this also creates subproblems, which are solved recursively using the same method that was used in solving the original problem. The major contributions of using the key reaction approach are that (1) Synit is not restricted to a backwards search from the target alone, and (2) The version of means-ends analysis that is used is an improvement over its traditional implementation because difference tables are made unnecessary. Previous relevant work is also discussed and related to the key reaction approach, and retrosynthetic methods are compared to Synit. Solutions by Synit are provided in the appendix. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
The Isotach Messaging Layer: Ironman Design
Authors: Michael N. Lack, Perry N. M. Myers, Paul F. Reynolds, Craig C. Williams
Venue:  (2000)

In traditional parallel and/or distributed systems, synchronization among nodes requires relatively expensive mechanisms such as locks and barriers. An Isotach network inexpensively provides strong guarantees regarding message delivery order, thus allowing for sequential consistency and atomicity at a much lower cost. The previous implementation of Isotach was built upon a third-party messaging layer, which resulted in unnecessary overhead and complications. This paper describes a complete design and implementation of a new messaging layer to support Isotach in a Linux/Myrinet network environment. The new system is fully integrated with previously designed Isotach custom hardware devices.
We Have Never-Forgetful Flowers In Our Garden: Girls'' Responses to Electronic Games
Authors: Kori Inkpen, Rena Upitis, Maria Klawe, Joan Lawry, Ann Anderson, Mutindi Ndunda, Kamran Sedighian, Steve Lerous, David Hsu
Venue:  (1993)

Electronic Games for Education in Math and Science (E-GEMS) is a large-scale research project designed to increase the proportion of children who enjoy learning and mastering mathematical concepts through the use of electronic games. This paper describes one piece of research that examines how girls interact within an electronic games environment. Three interrelated questions are addressed in this paper: What interest do girls show in electronic games when the games are presented in an informal learning environment? How do girls play and watch others play? How does the presence of others in the immediate vicinity influence the ways that girls play? The research described was conducted at an interactive science museum, Science World BC, during the summer of 1993. Children were observed while they played with various electronic games, both video and computer. In addition, interviews were conducted with the children and timed samplings were recorded. Our observations and interviews show that girls have an interest in electronic games and enjoy playing. Girls were particularly interested when given the opportunity to socially interact with others. In addition, they indicated a preference for playing on computers over video game systems.
MISC: A MASSIVELY PARALLEL ARCHITECTURE FOR ASSOCIATIVE-BASED ARTIFICIAL INTELLIGENCE (Ph.D. Thesis)
Authors: James D. Roberts
Venue:  (1995)

Parallel architectures are required to provide the computational power for future artificial intelligence research and applications. Massively parallel processing is emerging as an important alternative to prior approaches to parallel AI. Unfortunately, contemporary general-purpose machines are optimized for numeric codes while application-specific machines do not fully address the wide variety of algorithms needed by large-scale knowledge processing. This dissertation investigates overcoming these limitations through associative content-based processing of complex dynamic data objects, focusing on retrieval from large knowledge bases. Analysis of algorithm-architecture-technology interactions is the foundation of the MISC architecture development. To accomplish this, we develop an associative pseudocode, new parallel algorithms, and an enhanced design tool. The SEGUL pseudocode features nested multisets, allowing the expression of knowledge processing algorithms in a machine-independent manner for subsequent characterization. Three algorithms serve as the focus of the analysis: an associative memory neural network, a semantic network, and a graph knowledge-base. Suspense, the early analysis tool, projects speed and cost measures for architectural alternatives. Functional-level simulation combined with early analysis of a hypothetical implementation provide cost-performance projections for evaluating the resulting architecture. The MISC system architecture is comprised of multiple small data-parallel arrays, as the the number of processors required by any one of the algorithms scales sublinearly with respect to the knowledge base size. The array processors feature a general-purpose core and additional functional units to improve content-based knowledge processing. Each processor also has high bandwidth access to a large off-chip memory, and inter-processor communication is by a wide-link extended mesh network. Analysis shows that advanced packaging is a cost-effective means of achieving the required high connectivity. Simulation of the MISC architecture for the suite of three algorithms indicates more than a factor of ten improvement in both speed and cost-performance over a massively parallel architecture tailored for numeric codes. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
Automated Timing Analysis of Real-time Programs
Authors: W. M. Ferreira, M. R. Hill, M. Joseph
Venue:  (1992)

ReStat is an interactive software tool for statically analysing the timing properties of real-time programs. Given a distributed program, a description of an architecture and a scheduling discipline. ReStat can be used to determine whether the implementation of the program on the architecture will meet a set of timing deadlines. The program may consist of a number of communicating processes and one process or more may be assigned to any processor. Each process is assumed to have a simple, nonterminating,cyclic structure. ReStat uses a method of static analysis which establishes the timing properties of a real-time program by examining finite execution segments. The method is syntactic and can be efficiently implemented. This paper gives a outline formal specification of the present version of the tool and illustrates its use as a design aid by way of examples. Keywords: deadlines, static analysis, scheduling, formal specification
A Power Efficient Speculative Fetch Architectur
Authors: Glenn Reinman, Brad Calder, Todd Austin
Venue:  (2000)

Low-power research has flourished recently, in an attempt to address packaging and cooling concerns of current microprocessor designs, as well as battery life for mobile computers. In this paper, we propose and evaluate a high performance, energy efficient front-end architecture. We outline a low-power instruction cache configuration, and examine the benefit of decoupling the tag component of our cache from the data component. This decoupling enables a sophisticated cache replacement algorithm and an accurate, but energy efficient, mechanism for speculative fetching. Cache blocks are initially verified by the tag component of the cache -- those that miss in the cache can be speculatively brought in from lower levels of the memory hierarchy. We introduce and analyze a number of auxiliary structures that enhance this design and maintain consistency between the time of verification and the actual cache block lookup. Our power efficient cache configuration provides a 43% reduction in energy dissipation over a comparable prefetching scheme for the benchmarks we examine, while attaining slightly better performance (measured in instructions per nanosecond).
MUTUAL INFORMATION, METRIC ENTROPY, AND RISK IN ESTIMATION OF PROBABILITY DISTRIBUTIONS
Authors: David Haussler, Manfred Opper
Venue:  (1996)

Assume $\{P_\theta: \theta \in \Theta\}$ is a set of probability distributions with a common dominating measure on a complete separable metric space $Y$. A state $\theta^* \in \Theta$ is chosen by Nature. A statistician gets $n$ independent observations $Y_1, \ldots, Y_n$ distributed according to $P_{\theta^*}$. For each time $t$ between 1 and $n$, based on the observations $Y_1, \ldots, Y_{t-1}$, the statistician produces an estimated distribution $Q_t$ for $P_{\theta^*}$, and suffers a loss equal to the average of L(P_{\theta^*},Q_t)$ over the observations. The cumulative risk for the statistician is the average total loss up to time $n$. Of special interest in information theory, data compression, mathematical finance, computational learning theory and statistical physics is the special case when the loss $L(P_{\theta^*},Q_t)$ is the relative entropy between the true distribution $P_{\theta^*}$ and the estimated distribution $Q_t$. Here the cumulative Bayes risk is the mutual information between the random parameter $\Theta^*$ and the observations $Y_1, \ldots, Y_n$. New bounds on this mutual information are given in terms of the Laplace transform of the Hellinger distance between distributions in $\Theta$. From these, bounds on the cumulative minimax risk are given in terms of the metric entropy of $\Theta$ with respect to the Hellinger distance. The assumptions required for these bounds are very general and do not depend on the choice of the dominating measure. They apply to both finite and infinite dimensional $\Theta$. They apply in some cases where $Y$ is infinite dimensional, in some cases where $Y$ is not compact, in some cases where the distributions are not smooth, and in some parametric cases where asymptotic normality of the posterior distribution fails. Using these bounds for cumulative relative entropy risk, we also examine the Bayes and minimax risk of this game at specific times $t$ for various loss functions $L$, including the relative entropy, the squared Hellinger distance, and the $L_1$ distance.