ppxscal/embedding_network huggingface dataset:
Hot mirroring: a method of hiding parity update penalty and degradation during rebuilds for RAID5
Authors: Kazuhiko Mogi, Masaru Kitsuregawa
Venue: ACM SIGMOD Record (1996)

This paper proposes a storage management scheme for disk arrays, named hot mirroring. In this scheme, storage space is partitioned into two regions. One is the mirrored region, which is characterized by high performance and low storage efficiency. The other is the RAID5 region, which is characterized by low performance and high storage efficiency. Hot data blocks are stored in the former area, while cold blocks are stored in the latter. In addition, mirrored pairs and RAID5 stripes are orthogonally laid out, through which the performance degradation during rebuilding is minimized. Hot block clustering in hot mirroring achieves higher performance than conventional RAID5 arrays. The potential of hot mirroring is examined through extensive simulation.
Experimental investigation of an interior search method within a simplex framework
Authors: Gautam Mitra, Mehrdad Tamiz, Joseph Yadegar
Venue: Communications of the ACM (1988)

A feasible direction method for solving Linear Programming (LP) problems, followed by a procedure for purifying a non-basic solution to an improved extreme point solution have been embedded within an otherwise simplex based optimizer. The algorithm is designed to be hybrid in nature and exploits many aspects of sparse matrix and revised simplex technology. The interior search step terminates at a boundary point which is usually non-basic. This is followed by a series of minor pivotal steps which lead to a basic feasible solution with a superior objective function value. It is concluded that the procedures discussed in this article are likely to have three possible applications, which are (i) improving a non-basic feasible solution to a superior extreme point solution, (ii) an improved starting point for the revised simplex method, and (iii) an efficient implementation of the multiple price strategy of the revised simplex method.
On Families of Sets of Integral Vectors Whose RepresentativesForm Sum-Distinct Sets
Authors: Dusan B. Jevtic
Venue: SIAM Journal on Discrete Mathematics (1995)

We study the size of a collection $\{{\cal P}_1,\ldots,{\cal P}_T\}$ whose members ${\cal P}_i$, $i=1,\ldots,T$, are disjoint sets of integral vectors such that $\sum_{i=1}^T \bar x_i$ are all distinct and each $n$-tuple $\bar x_i$ comes from a different set ${\cal P}_i$. In particular, if ${\cal P}_i=\{\bar 0_n,\bar x_i\}$, we have a well-known problem on maximum cardinality of sum-distinct sets of integral vectors. We state bounds on $n^{-1}\sum_{i=1}^T \log_2\vert{\cal P}_i\vert$ and give a construction that meets the lower bound.
Simulation of compressible flow on a massively parallel architecture
Authors: Dan Williams, Luc Bauwens
Venue: Scientific Programming (1995)

This article describes the porting and optimization of an explicit, time-dependent, computational fluid dynamics code on an 8,192-node MasPar MP-1. The MasPar is a very fine-grained, single instruction, multiple data parallel computer. The code uses the flux-corrected transport algorithm. We describe the techniques used to port and optimize the code, and the behavior of a test problem. The test problem used to benchmark the flux-corrected transport code on the MasPar was a two-dimensional exploding shock with periodic boundary conditions. We discuss the performance that our code achieved on the MasPar, and compare its performance on the MasPar with its performance on other architectures. The comparisons show that the performance of the code on the MasPar is slightly better than on a CRAY Y-MP for a functionally equivalent, optimized two-dimensional code.
User-level threads on a general hardware interface
Authors: K. R. Mayes, S. Quick, B. C. Warboys
Venue: ACM SIGOPS Operating Systems Review (1995)

Moving resource management out of the operating system kernel facilitates a high degree of customisation. The lowest layer of the Arena system provides an abstract interface to conventional processor hardware (Mayes, 1993; Quick, 1995). The idea is to encapsulate the hardware behind an interface with certain low-level concepts which are generally applicable to any processor. Localization of hardware-dependency has the effect of increasing modularity and thus portability. This encapsulation, termed the Arena hardware object (HWO) supports portable user-level customizable resource management (Mayes et al., 1994). The aim is to remove resource management policy from the HWO whilst maintaining its integrity. The present paper deals with the Arena approach to the provision of pure user-level threads. Native implementations on Sparc and i486 processors are briefly described and performance figures are given. The compromise between reducing policy and maintaining integrity in the HWO implementations is discussed.
Split objects: a disciplined use of delegation within objects
Authors: Daniel Bardou, Christophe Dony
Venue: ACM SIGPLAN Notices (1996)

This paper's primary aim is to improve the understanding of the delegation mechanism as defined in [18]. We propose a new characterization of delegation based on the notions of name sharing, property sharing and value sharing. It allows us (1) to clearly differentiate delegation from class-inheritance in particular and more generally from other inheritance mechanisms and (2) to explain how a founded use of delegation relies on a correct semantics of variable property sharing between objects connected by a delegation link. We then describe a model of split objects which is proposed as an example of a disciplined and semantically founded use of delegation, where property sharing expresses viewpoints within objects.
Literate Smalltalk Programming Using Hypertext
Authors: Kasper Østerbye
Venue: IEEE Transactions on Software Engineering (1995)

The problem examined in this paper is: How and to what extent can hypertext support literate programming in Smalltalk? In order to examine this question we have created a hypertext system which allows us to write Smalltalk code and documentation, and to link code and documentation freely. The literate programs created in hypertext differ from those created with traditional literate programming tools. The main difference is that hypertext-based program exposition promotes description of program dependencies and is perhaps less suited for the detailed exposition of algorithms.
Visualizing performance in the frequency plane
Authors: D. G. Keehn
Venue: ACM SIGMETRICS Performance Evaluation Review (1995)

A method of showing the performance limiting effects of a product form queueing network as lines, planes, etc in a J dimensional space is given. The location of a certain critical point (Little's Law Point) in this space allows the asymptotic calculation of the normalizing constant G(K) of the network. This Little's Law point (LLP) is found by applying Little's Law to the augmented system generating function of the BCMP [1] network. The computational complexity of this algorithm is the Order (number of chains cubed * number of service centers in the system). Comparisons of numerical accuracy with other methods (Convolution, and another asymptotic method) are given.
Demand-driven register allocation
Authors: Todd A. Proebsting, Charles N. Fischer
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1996)

A new global register allocation technique, demand-driven register allocation, is described. Demand-driven register allocation quantifies the costs and benefits of allocating variables to registers over live ranges so that high-quality allocations can be made. Local allocation is done first, and then global allocation is done iteratively beginning in the most deeply nested loops. Because local allocation precedes global allocation, demand-driven allocation does not interfere with the use of well-known, high-quality local register allocation and instruction-scheduling techniques.
Opportunities at ARPA, NSF, and elsewhere
Authors: Xiaolei Qian
Venue: ACM SIGMOD Record (1995)

We first report the relatively minor development on the federal budget. We then touch upon announcements from ARPA, NSF, Defense Nuclear Agency, Rome Laboratory, US Special Operations Command, and Office of National Drug Control Policy. We also report a recent ARPA reorganization.
Computer self-efficacy and outcome expectancy: the effects on the end-user's job satisfaction
Authors: John W. Henry, Robert W. Stone
Venue: ACM SIGCPR Computer Personnel (1995)

Information technology has expanded into the realm of almost every organizational environment. The past 30 years have witnessed an emphasis on the technological attributes of these systems, often with little regard for human factors. Even more importantly, as information technology use becomes nonvolitional, assessment of the impact of these systems on end-user job satisfaction becomes essential for successful implementation and use. This research presents and empirically tests a theoretically sound model of how information system management support, system experience, and ease of system use affect the end-user's sense of computer self-efficacy and outcome expectancy. Subsequently, the impacts of computer self-efficacy and outcome expectancy on the end-users' satisfaction with their jobs are examined. The empirical results validate the model indicating that computer self-efficacy and outcome expectancy affect the end-user's job satisfaction as well as mediate the impacts of management support, system experience, and ease of system use. From these results, implications for practicing managers and directions for future research are discussed.
StormWatch: a tool for visualizing memory system protocols
Authors: Trishul M. Chilimbi, Thomas Ball, Stephen G. Eick, James R. Larus
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

Recent research has offered programmers increased options for programming parallel computers by exposing system policies (e.g., memory coherence protocols) or by providing several programming paradigms (e.g. message passing and shared memory) on the same platform. Increased flexibility can lead to higher performance, but it is also a double-edged sword that demands a programmer understand his or her application and system at a more fundamental level. Our system, Tempest, allows a programmer to select or implement communication and memory coherence policies that fit an application's communication patterns. With it, we have achieved substantial performance gains without making major changes in programs. However, the process of selecting, designing, and implementing coherence protocols is difficult and time consuming, without tools to supply detailed information about an application's behavior and interaction with the memory system. StormWatch is a new visualization tool that aids a programmer through four mechanisms: tightly-coupled bidirectionally linked views, interactive filters, animation, and performance slicing. Multiple views present several aspects of program behavior simultaneously and show the same phenomenon from different perspectives. Real-time linking between views enables a programmer to explore levels of abstraction by changing a view and observing the effect on other views. Interactive filters, along with bidirectional linking, can isolate the effects of statements, loops, procedures, or files. StormWatch can also animate a program's dynamic behavior to show the evolution of program execution and communication. Finally, performance slicing captures causality among events. The examples in the paper illustrate how StormWatch helped us substantially improve the performance of two applications.
A field study of exploratory learning strategies
Authors: John Rieman
Venue: ACM Transactions on Computer-Human Interaction (TOCHI) (1996)

It has suggested that interactive computer users find &ldquo;exploratory learning&rdquo; to be an effective and attractive strategy for learning a new system or investigating unknown features of familiar software. In exploratory learning, instead of working through precisely sequenced training materials, the user investigates a system on his or her own initiative, often in pursuit of a real or artificial task. The value of exploratory learning has been studied in controlled settings, with special attention newly acquired systems, be there has been little investigation of its occurrence in natural situations or in support of ongoing learning. To address this question, a field study of the behavior and attitudes of computer users in everyday working situations was performed, using diaries and structured interviews that focused on learning events. The study showed that task-oriented exploration was a widely accepted method for learning, but that it often required support from manuals and from other users or system support personnel. Exploration not related to a current or pending task was infrequent, and most users believed it to be inefficient. These findings have implications for the design of systems, documentation, and training.
On the Generation of Random Binary Search Trees
Authors: Luc Devroye, John Michael Robson
Venue: SIAM Journal on Computing (1995)

We consider the computer generation of random binary search trees with $n$ nodes for the standard random permutation model. The algorithms discussed here output the number of external nodes at each level, but not the shape of the tree. This is important, for example, when one wishes to simulate the height of the binary search tree. Various paradigms are proposed, including depth-first search with pruning, incremental methods in which the tree grows with random-sized jumps, and a tree growing procedure gleaned from birth-and-death processes. The last method takes $O(\log^4 n)$ expected time.
On Polynomial-Time Learnability in the Limit of Strictly Deterministic Automata
Authors: Takashi Yokomori
Venue: Machine Learning (1995)

This paper deals with the polynomial-time learnability of a language class in the limit from positive data, and discusses the learning problem of a subclass of deterministic finite automata (DFAs), called strictly deterministic automata (SDAs), in the framework of learning in the limit from positive data. We first discuss the difficulty of Pitt's definition in the framework of learning in the limit from positive data, by showing that any class of languages with an infinite descending chain property is not polynomial-time learnable in the limit from positive data. We then propose new definitions for polynomial-time learnability in the limit from positive data. We show in our new definitions that the class of SDAs is iteratively, consistently polynomial-time learnable in the limit from positive data. In particular, we present a learning algorithm that learns any SDA M in the limit from positive data, satisfying the properties that (i) the time for updating a conjecture is at most O(lm), (ii) the number of implicit prediction errors is at most O(ln), where l is the maximum length of all positive data provided, m is the alphabet size of M and n is the size of M, (iii) each conjecture is computed from only the previous conjecture and the current example, and (iv) at any stage the conjecture is consistent with the sample set seen so far. This is in marked contrast to the fact that the class of DFAs is neither learnable in the limit from positive data nor polynomial-time learnable in the limit.
Fuzzy control of technological processes in APL2
Authors: Alexander O. Skomorokhov, K.-H. Reinhardt, G. Roche, M. Tielemann
Venue: ACM SIGAPL APL Quote Quad (1995)

A fuzzy control system has been developed to solve problems which are difficult or impossible to control with a proportional integral differential approach. According to system constraints, the fuzzy controller changes the importance of the rules and offers suitable variable values. The fuzzy controller testbed consists of simulator code to simulate the process dynamics of a production and distribution system and the fuzzy controller itself. The results of our tests confirm that this approach successfully reflects the experience gained from skilled manual operations. The simulation and control software was developed in APL2/2 running under OS/2. Several features of this product, especially multitasking, the ability to run AP124 and AP207 windows concurrently, and the ability to run concurrent APL2 sessions and interchange data among them were used extensively in the simulation process.
Quantum modeling of distributed object computing
Authors: James M. Butler
Venue: ACM SIGSIM Simulation Digest (1994)

Distributed object computing is rapidly gaining notice in the computer engineering community. In response, productized support for these systems is increasing. However, few tools exist for the design and modeling of distributed object systems. Clearly, large scale and mission critical systems are most affected by this deficiency. To attain a level of tractability in large scale design and verification, dynamic models are essential. This paper introduces two modeling components. First, the LCN (Loosely Coupled Network) model supports the definition of real-world network topologies and multicomputer systems. Second, the DCO (Distributed Cooperative Objects) model provides a system-independent method of representing complex, object oriented computing structures. These components are assigned random variables (e.g., bandwidths, error rates, compute loads, data volumes, etc.) that provide a basis for dynamic behavior. Through surjective mapping of DCO software onto LCN hardware, the complete OSM (Object System Mapping) model is created. It is shown that OSM systems can model all modes of distributed object behavior found in the current state of Object Request Broker (ORB) technology while under the constraints of modern network structures. The paper concludes with a qualitative analysis of these behaviors and sets the foundation for a distributed object simulation facility.
Data interpretation and experiment planning in performance tools
Authors: Allen D. Malony
Venue: ACM SIGMETRICS Performance Evaluation Review (1995)

The parallel scientific computing community is placing increasing emphasis on portability and scalability of programs, languages, and architectures. This creates new challenges for developers of parallel performance analysis tools, who will have to deal with increasing volumes of performance data drawn from diverse platforms. One way to meet this challenge is to incorporate sophisticated facilities for data interpretation and experiment planning within the tools themselves, giving them increased flexibility and autonomy in gathering and selecting performance data. This panel discussion brings together four research groups that have made advances in this direction.
Adaptive block rearrangement
Authors: Sedat Akyürek, Kenneth Salem
Venue: ACM Transactions on Computer Systems (TOCS) (1995)

An adaptive technique for reducing disk seek times is described. The technique copies frequently referenced blocks from their original locations to reserved space near the middle of the disk. Reference frequencies need not be known in advance. Instead, they are estimated by monitoring the stream of arriving requests. Trace-driven simulations show that seek times can be cut substantially by copying only a small number of blocks using this technique. The technique has been implemented by modifying a UNIX device driver. No modifications are required to the file system that uses the driver.
Algorithm design
Authors: Robert E. Tarjan
Venue: Communications of the ACM (1987)

The quest for efficiency in computational methods yields not only fast algorithms, but also insights that lead to elegant, simple, and general problem-solving methods.
Evaluation of location area planning scenarios in future mobile telecommunication systems
Authors: J. G. Markoulidakis, G. L. Lyberopoulos, D. F. Tsirkas, E. D. Sykas
Venue: Wireless Networks (1995)

In third generation mobile telecommunication systems, signalling requirements due to location updating and paging are expected to be remarkable, mainly because of the huge number of mobile subscribers. Location area planning is characterised by the trade-off between the number of location updates and the amount of paging signalling that the network has to deal with. Location area planning should be based on criteria which guarantee that signalling load will be kept under tolerable levels. Various approaches for location area planning in a city environment the worst case environment&mdash;are discussed in this paper. The simplest approach is the use of heuristic algorithms for approximating the optimum location area configuration. Then more complex scenarios which are based on geographical criteria (population distribution, highway topology, etc.) are investigated. Finally, user mobility characteristics are taken into account in the most complex scenarios. All scenarios are applied over a simulation model representing a city area, providing us with a very clear view of their performance characteristics.
A unified approach to topology generation and area optimization of general floorplans
Authors: Partha S. Dasgupta, Susmita Sur-Kolay, Bhargab B. Bhattacharya
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

In this paper, it is shown that for any rectangularly dualizable graph, a feasible topology can be obtained by using only either straight or Z-cutlines recursively within a bounding rectangle. Given an adjacency graph, a potential topology, which may be nonslicible and is likely to yield an optimally sized floorplan, is produced first in a top-down fashion using heuristic search in AND-OR graphs. The advantage of this technique is fourfold : (i) accelerates top-down search phase, (ii) generates a floorplan with minimal number of nonslice cores, (iii) ensures safe routing order without addition of pseudo-modules, and (iv) solves the bottom-up algorithm efficiently for optimal sizing of general floorplans in the second phase.
An open simulation architecture for Force XXI
Authors: John A. Hamilton,  Jr., Udo W. Pooch
Venue: Proceedings of the 27th conference on Winter simulation (1995)

Force XXI will be America's Army in the 21st century. New technology, a post-Cold War world and a declining force structure have made simulation a critical means for defining and implementing Force XXI. Military organizations are hierarchical. In combat, these command levels operate simultaneously with varying levels of coupling. A platoon on platoon operation can be significantly affected by unilateral actions of higher level friendly or enemy headquarters. A high-fidelity simulation must be able to represent the simultaneous actions of several command echelons. A multi-level simulation approach is presented in which different echelons of command can view objects at varying levels of detail consistently. A task force commander should be able to view the position and movement of a tank platoon on a map or a virtual view of the battlefield as seen from the platoon leader's hatch or real-time live video from an actual tank on the ground. Each view must be logically consistent with each other, so that the mountain on the map sheet affects movement in the same manner as the virtual mountain and the actual mountain seen via live video. Various combinations of live, virtual and constructive simulations will run concurrently in the same simulation infrastructure. Expert systems will control constructive simulation nodes lacking human players. At any level in the simulation human players and expert system players may be interchanged. The opposing force will be similarly configured. Force on force virtual simulations will be supported in the simulation infrastructure. The resulting open simulation architecture (OSA) is discussed in detail.