Showing papers on "Temporal isolation among virtual machines published in 1979"

Virtual Machine Technology: A Bridge From Large Mainframes To Networks Of Small Computers

Abstract: The cost effectiveness of small computers (minis and micros) makes it desirable to use networks of such machines in a manner that provides the functionality available on large systems, but takes advantage of the potentially greater reliability of a distributed system. This paper explores how traditional virtual machine concepts can be extended to networks of cooperating virtual machines running on multiple processors. Some design approaches useful in building systems of cooperating virtual machines are then discussed.

The changing virtual machine environment: interfaces to real hardware, virtual hardware, and other virtual machines

Abstract: This paper is a survey of changes to virtual machine interfaces, implementation, architecture, and simulation techniques as they affect IBM System/370 and 303X (3031, 3032, 3033) processors, the system control program to which virtual machines interface, and other virtual machines executing on the same real computing system or elsewhere. The paper seeks to summarize such changes and provide a perspective on the virtual machine environment. New uses of virtual machine subsystems are discussed as they relate to inter-virtual-machine communication.

Virtual control storage: security measures in VM/370

Abstract: The architecture of a virtual machine system has specific advantages over that of conventional operating systems because virtual machines are well separated from one another and from the control program. This structure requires that a protected, multi-user resource manager be placed in a distinct virtual machine because the protection domain and scheduling unit are one entity, the virtual machine. But cooperation between distinct virtual machines necessarily entails scheduling overhead and often delay. This paper describes an experimental extension to VM/370 whereby a distinct execution and data domain (Virtual Control Storage) is made available to virtual machines that require access to a resource manager, without requiring a change in the scheduling unit. Thus scheduling overhead and delays are avoided when transition is made between user program and resource manager. A mechanism is described for exchanging data between execution domains by means of address-space mapping.

A formal approach for communication between logically isolated virtual machines

Abstract: The growing use of the virtual machine concept has resulted in the necessity for communication between the virtual machines. The design and operation of the Virtual Machine Communication Facility is discussed as an approach to offering such communication. The facility is an interface allowing a logical connection between two or more virtual machines. Potential applications for this facility conclude the discussion.

Virtual machines and distributed processing

Abstract: This paper proposes a taxonomy for classifying networks of virtual machines in terms of the complexity of the communication mechanisms and the layering of communication functions. It shows how four currently implemented networks using (1) the virtual service machine approach, (2) embedding of communication functions in the control program, (3) a packet switching communication subnetwork and (4) a multiprocessor system fit into this framework. Implications for future developments are then discussed.

Partitioning For Virtual Machine Efficiency

Abstract: The virtual machine concept, enabling individual users to concurrently access a computer's resources, has long been accepted for business applications and utilized by software implementors. Current implementations of the virtual machine concept have been achieved almost exclusively through the use of software (e.g., virtual machine monitors) Use of the concept for high performance, application processes has been constrained by the overhead resulting from the software monitor. This includes time required for application process dispatch and communication between the associated virtual machines whenever cooperation is required to meet a system objective.

A virtual machine emulator for performance evaluation (Summary)

Abstract: Virtual machines have long been used for functional testing of operating systems and to obtain the services of multiple operating systems from a single machine They have not been used for performance evaluation however, because the timing observed by a program executing in a virtual machine is unpredictable and dependent on such factors as system load, real operating system overhead, real scheduling, etc System level performance evaluation of hardware and operating systems has typically been done by hardware prototyping and dedicated machine benchmarkingThis paper introduces the notion of virtual hardware prototyping for system performance evaluation The approach makes use of the virtual machine concept by adding timing simulation to virtual machine support The resulting virtual machines reproduce both machine timing and machine architecture They are then useful for system performance evaluation

Virtual machine dispatching under fairness constraints

Abstract: The paper analyzes the problems of low level dispatching under predictability constraints, with good responsiveness and low overhead. It is shown that nonpreemptive and/or round-robin disciplines fail for the general case. A novel algorithm is proposed based on sorting at time slice intervals. Simulation results are used to discuss the properties of the new dispatching algorithm.