Several menu configurations were designed to provide an independent assessment of the influence of breadth, depth and number of responses on computer menu search performance. The menu hierarchy consisted of a binary t...
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Several menu configurations were designed to provide an independent assessment of the influence of breadth, depth and number of responses on computer menu search performance. The menu hierarchy consisted of a binary tree of category descriptor terms with 64 terminal options. Standard menus tested were 2 options on each of 6 sequential frames (2 6 ) and 4 options on 3 frames (4 3 ). Another menu (Upcoming Selections) was developed with 6 frames in which the binary choice on each frame was shown in the presence of options at the next menu level. Menus developed for separating the effects of number of frames and responses were configured with two menu levels per frame and responses were required to either one or both levels. Number of responses was the most important factor affecting execution time. The highest accuracy was found with the Upcoming Selections menu but that menu also resulted in the slowest execution time. A modified Upcoming Selections menu was developed which allowed participants to respond to each level or to bypass the higher level on each frame. Considering both speed and accuracy, that configuration yielded the best performance of all menus tested.
This paper investigates the implementation of fast direct methods for solving the three-dimensional Poisson equation on loosely coupled hypercube multiprocessors. As a preliminary step, the problem of computing multip...
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This paper investigates the implementation of fast direct methods for solving the three-dimensional Poisson equation on loosely coupled hypercube multiprocessors. As a preliminary step, the problem of computing multiple FFTs is considered and two different algorithms are compared. These algorithms are then used to implement two FFT-based fast Poisson solvers. Proceeding both with experiments and with performance models, these two solvers are studied and compared. No single algorithm is superior in all ranges of the parameters and the best choice depends upon problem size, number of processors and communication costs. In closing, two additional parallel algorithms for solving the Poisson equation are proposed, both of which appear to be competitive.
Leslie Lamport presented a set of axioms in 1979 that capture the essential properties of the temporal relationships between complex and perhaps unspecified activities within any system, and proceeded to use this axio...
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Leslie Lamport presented a set of axioms in 1979 that capture the essential properties of the temporal relationships between complex and perhaps unspecified activities within any system, and proceeded to use this axiom system to prove the correctness of sophisticated algorithms for reliable communication and mutual exclusion in systems without shared memory. As a step toward a more complete metatheory of Lamport's axiom system, this paper determines the extent to which that system differs from systems based on 'atomic,' or indivisible, actions. Theorem 1 shows that only very weak conditions need be satisfied in addition to the given axioms to guarantee the existence of an atomic 'model,' while Proposition 1 gives sufficient conditions under which any such model must be a 'faithful' representation. Finally, Theorem 2 restates a result of Lamport showing exactly when a system can be thought of as made up of a set of atomic events that can be totally ordered temporally. A new constructive proof is offered for this result.
The author surveys many of the issues involved in designing online documentation. She covers choosing a goal for online documentation, understanding the constraints on a design, and understanding the implications of a...
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The author surveys many of the issues involved in designing online documentation. She covers choosing a goal for online documentation, understanding the constraints on a design, and understanding the implications of a design for writers and users. The survey is mostly from the perspective of a designer or project planner concerned with issues in both software development and document development.
Internet streaming single input multiple data extensions (ISSE) are developed to enable a new level of visual computing on the volume PC platform. The performance of these instructions can be scaled with each new micr...
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Internet streaming single input multiple data extensions (ISSE) are developed to enable a new level of visual computing on the volume PC platform. The performance of these instructions can be scaled with each new microarchitecture implementation and semiconductor process change. It enable new levels of visual realism and real-time video encoding on the PC platform and also enhance the PC's video decode, speech recognition, and image manipulation capabilities.
This paper discusses the use of software work vectors as the fundamental form for workload characterization and modeling purposes. Software work is one of the basic properties of software physics, and has the property...
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This paper discusses the use of software work vectors as the fundamental form for workload characterization and modeling purposes. Software work is one of the basic properties of software physics, and has the property of being independent of processor speed, configuration design, and unaffected by other workload elements. The general vector form of characterization is shown, equations for calculating work given, an example is shown, and its uses considered.
A report is presented on the development and testing of a sampling technique designed to extract accurate measurements of reference string characteristics while recording only a part of the complete reference string. ...
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A report is presented on the development and testing of a sampling technique designed to extract accurate measurements of reference string characteristics while recording only a part of the complete reference string. The cost of the measurements is controlled by the sampling rate. Results are based on experiments using synthetic reference strings from an LRU generative model. 12 refs.
Problems of software conversion and some recommendations about planning and implementation of this procedure are given including managing the entire conversion project, staff category suggestion, contracting for conve...
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Problems of software conversion and some recommendations about planning and implementation of this procedure are given including managing the entire conversion project, staff category suggestion, contracting for conversion services, estimating conversion costs, and benchmark portability.
We collect and analyze a snapshot of data from 10,568 file systems of 4801 Windows personal computers in a commercial environment. The file systems contain 140 million files totaling 10.5 TB of data. We develop analyt...
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We collect and analyze a snapshot of data from 10,568 file systems of 4801 Windows personal computers in a commercial environment. The file systems contain 140 million files totaling 10.5 TB of data. We develop analytical approximations for distributions of file size, file age, file functional lifetime, directory size, and directory depth, and we compare them to previously derived distributions. We find that file and directory sizes are fairly consistent across file systems, but file lifetimes vary widely and are significantly affected by the job function of the user. Larger files tend to be composed of blocks sized in powers of two, which noticeably affects their size distribution. File-name extensions are strongly correlated with file sizes, and extension popularity varies with user job function. On average, file systems are only half full.
In this paper we consider the problem of scheduling different classes of customers on multiple distributed servers to minimize an objective function based on per-class mean response times. This problem arises in a wid...
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In this paper we consider the problem of scheduling different classes of customers on multiple distributed servers to minimize an objective function based on per-class mean response times. This problem arises in a wide range of distributed systems, networks and applications. Within the context of our model, we observe that the optimal sequencing strategy at each of the servers is a simple static priority policy. Using this observation, we argue that the globally optimal scheduling problem reduces to finding an optimal routing matrix under this sequencing policy. We formulate the latter problem as a nonlinear programming problem and show that any interior local minimum is a global minimum, which significantly simplifies the solution of the optimization problem. In the case of Poisson arrivals, we provide an optimal scheduling strategy that also tends to minimize a function of the per-class response time variances. Applying our analysis to various static instances of the general problem leads us to rederive many results, yielding simple approximation algorithms whose guarantees match the best known results.
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