This paper deals with the problem of reliability in a hardware/software system. More specifically it deals with the strategy used to achieve reliability in a particular hardware/s oftware system built by the author an...
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A many-state Markov model has been developed for the purpose of providing various performance criteria for computer software. The software system under consideration is assumed to be fairly large, of the order of 105 ...
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This paper describes the maintenance and enhancement of the computer Sciences Teleprocessing System (CSTS) and its component processors. CSTS is the system offered by the INFONET Division of computer Sciences Corporat...
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This paper describes the maintenance and enhancement of the computer Sciences Teleprocessing System (CSTS) and its component processors. CSTS is the system offered by the INFONET Division of computer Sciences Corporation to provide nationwide conversational and batch teleprocessing service. In the first section, the organization of the project personnel and major activities of project departments arc described. The second section describes the process by which tunctional enhancements and error corrections arc implemented. The final section describes testing techniques and procedures used during implementation. The project staff is organized into implementation departments and service departments. Implementation departments develop new fcatures of the system, corrections to errors, and improvements in system operation, especially in reduction of software ovcrhcad. Implemcntatton departments are organized by system software functions such as operating system (device control, task management, and file management), language processors and data management systems, communications software, and applications. The service departments arc system integration, performance analysis, product management and system test. Thc Iunctions pcrformcd by thcsc departments arc describcd. Also dcscribcd arc the system evolution conferences and the periodic review of enhancements by a Change Advisory Board. During the development of a new version of the system, effective tracking of the status of changed modules is essential. The data base and process used to track new features, error corrections and changed component modules are described. The flow of implemented changes through system integration and system test is delineated, as is the development and verification of change documentation for users, administrators and operations personnel. The final section of the paper describes the design and documentation of test programs and the organization of test sets. Effective test operations are
The language in which programs are written can have a substantial effect on their reliability. This paper discusses the design of programming languages to enhance reliability . It presents several general design princ...
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Two complementary methods which are employed in order to assure reliable computing are fault-intolerance and fault-tolerance. Faultintolerance depends on the elimination of the causes of unreliability prior to the sta...
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This paper presents model studies of some integrated feedback-driven scheduling systems for a multiprogrammed computer *** abstract can present only the conclusions of the studies and little of the supporting data and...
ISBN:
(纸本)9781450373777
This paper presents model studies of some integrated feedback-driven scheduling systems for a multiprogrammed computer *** abstract can present only the conclusions of the studies and little of the supporting data and *** basic format of the analysis is to fix a size for the local buffers and a total size for the collection buffers, to define a set of algorithms for the determination of the data removal quanta to the local buffers, the allocation of space in the collection buffers, and the look-ahead mechanism for input and then to evaluate the relative merits of the various strategies by the resulting CPU *** feedback algorithms are studied as examples in this work.
Efficient scheduling of jobs for computersystems is a problem of continuing concern. The applicability of scheduling methodology described in the operations research literature is severely restricted by the dimension...
ISBN:
(纸本)9781450373777
Efficient scheduling of jobs for computersystems is a problem of continuing concern. The applicability of scheduling methodology described in the operations research literature is severely restricted by the dimensionality of job characteristics, the number of distinct resource types comprising a computer system, the non-deterministic nature of the system due to both interprocess interaction and contention, and the existence of a multitude of constraints effecting job initiation times, job completion times, and job interactions. In view of the large number of issues which must be considered in job scheduling, a heuristic approach seems appropriate. This paper describes an initial implementation of such an approach based upon a fast, analytically driven, performance prediction tool.
It is generally agreed that a computer system's CPU utilization means little by itself, but there has been only a limited amount of research to determine the value of CPU utilization when used with other performan...
ISBN:
(纸本)9781450373777
It is generally agreed that a computer system's CPU utilization means little by itself, but there has been only a limited amount of research to determine the value of CPU utilization when used with other performance measures. This paper focuses on time-sharing systems (or similar systems such as some remote batch systems) as viewed by someone who wants to minimize the mean cost per job run on the *** paper considers cost per job to include both the computer cost (as allocated among all the jobs run on the system) and the user cost (where user cost is the time spent waiting for a response from the system multiplied by the user's wage rate). Given this approach, cost per job is a function of some constants (user wage rate, computer system cost, and mean processing time per job) and only one variable (CPU utilization). The model thus developed can be used to determine the optimum CPU utilization for any system. It can also be used to determine the value of different tuning efforts.
It is known that the regulation of the degree of multiprogramming is perhaps one of the most important factors determining the overall performance of a virtual memory computer. In this paper we present an approach whi...
ISBN:
(纸本)9781450373777
It is known that the regulation of the degree of multiprogramming is perhaps one of the most important factors determining the overall performance of a virtual memory computer. In this paper we present an approach which differs some what from the approaches usually taken to regulate the degree of multiprogramming, which are mainly derived from the working-set *** design a controller which will regulate the system in order to optimize a given performance measure. The controller is applied to a system where the critical resource is primary memory, and we are only concerned with systems where ineffective regulation leads to the phenomenon known as thrashing due to extensive paging *** the first section, the dynamics of the system we wish to regulate are investigated using an analytical model. The system consists of a set of terminals and of a resource loop (CPU, secondary memory device, file disk) shared by the users. Using classical assumptions about program behavior (e.g., life-time function), the throughput of the RL is obtained as a function of the degree of multiprogramming n (number of users sharing the resources at a given instant of time) and of the system parameters. This result provides a greater insight of the “plant” we wish to control. The mathematical results are validated and extended with data from simulation experiments using a more detailed model (overheads and non-exponential assumption).In the next section, a criterion called “dilatation” based on the utilization of the different resources is defined. From the analytical and simulation results of the first section, it can be shown that there exists a value no of the degree of multiprogramming which maximizes this criterion. The regulation of n to no is achieved by controlling the access of the users to the RL. The value of no is estimated in real-time through a continuous estimation of the two first moments of the criterion. Using these estimations, the decision of introducing or n
ASSET has been written to simulate time-continuous communication, control, and radar systems on the XDS Sigma 7. Both the detailed responses of such systems to specific inputs, and system performance characteristics s...
ISBN:
(纸本)9781450374057
ASSET has been written to simulate time-continuous communication, control, and radar systems on the XDS Sigma 7. Both the detailed responses of such systems to specific inputs, and system performance characteristics such as signal to noise ratio, probability of error, probability of detection, mean squared error, etc. can be measured with ASSET. In general, the simulation technique is to convert the continuous-time system to a sampled-data system, and then to represent the sampled-data system blocks by ASSET statements. ASSET was designed with three goals in mind: ease of programming, measurement accuracy, and efficient Monte Carlo simulation; careful choice of measurement technique and compiler design resulted in what the authors believe to be an optimum compromise between these sometimes conflicting requirements.
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