摘要:

AbstractThis paper describes the implementation of a test bed called SAHAYOG, for evaluating dynamic load‐sharing policies in which job‐transfer decisions are based on the state of the system. The test bed is implemented on a network of AT&T 3B2 minicomputers. It provides an interactive user interface for conducting load‐sharing experiments. Based on user‐specified parameters it creates independent job streams at different nodes in the network. Jobs are transferred among the nodes by the load‐sharing algorithm being evaluated. Each node collects data about the jobs, which are used to generate statistics about the experiment. Five load‐sharing algorithms are implemented and evaluated using the test bed under different load conditions and for various parameter values. These experiments confirm some earlier results about load sharing and also provide some new insights. SAHAYOG also contains an optional fault‐tolerance feature to handle single‐node failures, and evaluates the effect of fault tolerance on the performance of dif

ISSN:0038-0644    

DOI:10.1002/spe.4380190502

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractA high level of complexity is involved in program dynamics. A number of tools have been developed to assist the programmer in mastering this complexity in the various phases of software development. However, these tools are specifically oriented towards the monitoring of particular aspects of program behaviour. This paper presents the results of a systematic attempt at defining the user interface to an environment for program debugging, program performance evaluation and program structure analysis. This environment can be used to implement many common debugging techniques, and to evaluate important program performance indexes and program structure statistics. It supports both sequential and concurrent block‐oriented high‐level langua

ISSN:0038-0644    

DOI:10.1002/spe.4380190503

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper describes an implementation and performance evaluation of differentdeadlock preventionalgorithms. A deadlock prevention algorithm ensures that deadlock will never happen. The algorithms for deadlock prevention are proposed and implemented in a locally distributed system. A number of experiments were executed in a distributed system for various lengths of file operation and different numbers of files. The performance of the system and of each algorithm is evaluated and discussed. Some general results are derived for a single‐host and a distributed syste

ISSN:0038-0644    

DOI:10.1002/spe.4380190504

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper describes an algorithm for evaluating database queries represented as expressions in a logical language. Such a database query expression can be evaluated efficiently by focusing on the variable dependencies. The algorithm recursively computes the values of subexpressions to evaluate the input expression, but it avoids re‐evaluation of those subexpressions whose values are not affected by new variable assignments. The input expression is internally structured as a directed acyclic graph. Two additional techniques to improve efficiency of the evaluation are discussed: transformations of the input expression and special primitive database operations. Finally, its implementation in the natural language question‐answering system SPICOS is descri

ISSN:0038-0644    

DOI:10.1002/spe.4380190505

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

ISSN:0038-0644    

DOI:10.1002/spe.4380190501

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY