Virtual Operating System Research Articles

Computer Science for Geophysicists. Part III: Operating Systems, I/O and the Interrupt

In the last two articles, I have discussed computer systems at the level furthest removed from the average user, that of hardware and the limitations imposed by particular hardware architecture. In this article, I shall move one level closer to the user and consider operating systems, which give a computer its personality, and I/O (input/output), indicating how seismic data moves around a seismic computing system. This will include a discussion of the relative merits of virtual and nonvirtual operating systems, a perennially controversial subject in seismic computing systems. The article introduces all the most important concepts and provides a basis for the more geophysically orientated future articles.

Data management in FEM-based optimization software

A programming approach for design of software system for FEM-based optimization techniques is presented. The main emphasis of the paper is on presentation of techniques for efficient data management. General organization pf a design software system, called SADDLE, is given which utilizes the data management system presented. Main features of the SADDLE system are: modularity, efficient data management, software portability and efficiency on virtual and non-virtual machines. Numerical results are presented which show relative efficiency of the SADDLE data manager for a large structural design problem compared to the PRIMOS virtual memory operating system.

An object-based virtual operating system for the Ada programming support environment

As part of a major effort to increase programmer productivity, the U.S. Department of Defense has supported the design of an Ada Programming Support Environment (APSE) based on the Pebbleman/Stoneman sequence of documents [4]. We have recently completed the first phase of this design, incorporating a standardized re-hostable virtual operating system and a retargetable Ada compiler with appropriate support tools. To support the coexistence on this system of many large and small software development projects, a sophisticated centralized database has been proposed that incorporates the concepts of object-based architecture [5] as well as more conventional hierarchical file systems [1].

The evolution of the operating system EMAS 2900

AbstractAs a result of experiencing problems with manufacturer's software on the early 2900 machines Edinburgh University took the bold step of attempting to move the general purpose timesharing system EMAS from an ICL 4–75 to an ICL 2970 computer. This paper describes the move together with the changes made and includes some preliminary performance figures from the new system. This implementation project has produced a major time‐sharing virtual memory operating system with a fraction of the effort required to implement the original system.

A virtual operating system

Moving to a new system is costly and error-prone. The problem can be reduced through use of a virtual operating system that disentangles computing environments from their underlying operating systems. The authors report on their successful experience in doing this and achieving inter-system uniformity at all three levels of user interface: virtual machine, utilities, and command language.

MVS in the classroom

The design principles of operating systems have been isolated and comprehensively expounded in texts that have appeared in the last decade which are suitable for either an advanced undergraduate or low-level graduate course. The topics covered are those listed in the course outline for CS10, Operating Systems and Computer Architecture II in Curriculum '78 (1). Generally one of two approaches is taken. The first is that the computer architecture already decides many of the fundamental policies of the operating system which it is to support. The second is that an operating system must solve certain allocation and scheduling problems in order to provide a user with a variety of services and to manage its own resources efficiently, and that once identified, solutions to the problems must be implemented on some computer architecture. In either case the text usually culminates with a limited project in which students design and implement some type of multiprogramming operating system. This report outlines the approach taken to present IBM's Multiple Virtual Storage Operating System (MVS) in this setting.

Throughput Capacity of a Sequence of Queues with Blocking Due to Finite Waiting Room

A tandem queueing system with blocking due to finite waiting room is considered. Maximum throughput is studied by an approximation for several cases. The service time can depend on the number of customers; intermediate arrivals can also be allowed. Some special models with two stations in sequence and blocking are examined. These models are used for the performance evaluation of computer systems. In particular, the maximum throughput for a virtual memory operating system and for a node-to-node protocol in a computer network are obtained.

Minimizing Garbage Collection as a Function of Region Size

Under a virtual storage operating system, the time spent by a list processing language on garbage collection varies in a complex manner with the amount of memory allocated. This dependence is investigated and strategies for minimizing the time spent on garbage collection are given.

Multiprogramming with virtual memory—a queueing model

A multiprogramming computing system which utilizes a virtual memory operating system, with paging-on-demand, is defined in queueing-theoretic terms. The validity and possible uses of such a model are discussed. Several quantities and measures of effectiveness, such as paging time, total system response time, and memory requirements are computed. The discussion and analysis place emphasis on exact, computable results.

Firmware/hardware support for operating systems

Firmware/hardware support for operating systems is described briefly, and proposed criteria for determining which operating system functions are the best candidates for firmware/hardware implementation are listed. A selected history of the area is presented in three sections: past and current research in support for virtual machines and two sections on past and current research in support for non -- virtual machine operating system functions.

Evaluation of markov program models in virtual memory systems

AbstractA first order Markov model of program behaviour is developed from FORTRAN program instruction data. The program model is evaluated by using it to generate page references for input into a simple virtual memory operating system (VMOS) simulation model. The actual trace data are also used to drive the VMOS model. In both cases the fault probability is obtained for different replacement rules, memory sizes and page sizes. A comparison of fault probabilities is used to determine the effectiveness of the Markov program model.