Using type-extension to organize virtual-memory mechanisms
Using type-extension to organize virtual-memory mechanisms
复制标题
使用类型扩展来组织虚拟内存机制
DOI：
10.1145/850716.850718
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
P. Janson
中科院分区：
文献类型：
--
作者：
P. Janson
目前正致力于生产易于理解、验证和开发的计算机系统。设计这样一个系统的一般方法包括将其分解为一组结构化的模块，以便可以单独理解、验证和开发模块，并且可以从对其模块的理解/验证中派生出对系统的理解/验证。虽然计算机系统中的许多机制已经成功地分解为一组结构化的模块，但还没有提出以这种方式组织系统的虚拟内存机制的技术。本文建议为此目的使用类型扩展。虚拟内存机制由一组实现抽象信息容器的类型管理器模块组成。该机制的结构反映了所实现的容器的结构。虽然使用类型扩展来组织虚拟内存机制在概念上很简单，但在实践中很难实现。所有现有的或建议的类型扩展使用都假定存在统一可访问的信息容器，这些容器总是可以扩展并受到保护。在虚拟内存机制中使用类型扩展会引发实现问题，因为没有实现这样的容器。它们的实现正是虚拟内存机制的目标。除了解释如何在虚拟内存机制中支持类型扩展之外，本文还简要讨论了它在商业通用分时系统内核重组中的一些应用。最后，介绍了该案例研究中有关操作系统组织的一些结果。
Much effort is currently being devoted to producing computer systems that are easy to understand, to verify and to develop. The general methodology for designing such a system consists of decomposing it into a structured set of modules so that the modules can be understood, verified and developed individually, and so that the understanding/verification of the system can be derived from the understanding/verification of its modules. While many of the mechanisms in a computer system have been decomposed successfully into a structured set of modules, no technique has been proposed to organize the virtual memory mechanism of a system in such a way.The present paper proposes using type extension for that purpose. The virtaul memory mechanism consists of a set of type manager modules implementing abstract information containers. The structure of the mechanism reflects the structure of the containers that are implemented. While using type extension to organize a virtual memory mechanism is conceptually simple, it is hard to achieve in practice. All existing or proposed uses of type extension assume the existence of information containers that are uniformly accessible, can always be grown and are protected. Using type extension inside a virtual memory mechanism raises implementation problems since such containers are not implemented. Their implementation is precisely the objective of the virtual memory mechanism. In addition to explaining how type extension can be supported inside a virtual memory mechanism, the paper briefly discusses some aspects of its application to the reorganization of the kernal of a commercial, general-purpose, time-sharing system. It concludes by presenting some results of that case study concerning the organization of operating systems.