In this chapter, we discuss various ways to manage memory. The memory- management algorithms vary from a primitive bare-machine approach to paging and segmentation strategies. Each approach has its own advantages and disadvantages. Selection of a memory-management method for a specific system depends on many factors, especially on the hardware design of the system. As we shall see, many algorithms require hardware support, leading many...

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Lecture Operating system concepts (Sixth ed) - Chapter 8: Deadlocks. After studying this chapter you will be able to develop a description of deadlocks, which prevent sets of concurrent processes from completing their tasks; to present a number of different methods for preventing or avoiding deadlocks in a computer system.

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In chapter 4, we introduced threads to the process model. On operating systems that support them, it is kernel-level threads not processes that are in fact being scheduled by the operating system. However, the terms "process scheduling" and "thread scheduling" are often used interchangeably. In this chapter, we use process scheduling when discussing general scheduling concepts and thread scheduling to refer to thread-specific ideas.

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The process model introduced in Chapter 4 assumed that a process was an executing program with a single thread of control. Many modern operating systems now provide features for a process to contain multiple threads of control. This chapter introduces many concepts associated with multithreaded computer systems and covers how to use Java to create and manipulate threads. We have found it especially useful to discuss how a Java thread maps to...

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Virtual memory can be a very interesting subject since it has so many different aspects: page faults, managing the backing store, page replacement, frame allocation, thrashing, page size. The objectives of this chapter are to explain these concepts and show how paging works.

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In this chapter, we begin a discussion of file systems at the lowest level: the structure of secondary storage. We first describe the physical structure of hard disks and magnetic tapes. We then describe disk-scheduling algorithms, which schedule the order of disk I/Os to maximize performance. Next, we discuss disk formatting and management of boot blocks, damaged blocks, and swap space. We conclude with an examination of the structure of...

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The role of the operating system in computer I/O is to manage and control I/O operations and I/O devices. Although related topics appear in other chapters, here we bring together the pieces to paint a complete picture of I/O. First, we describe the basics of I/O hardware. Next, we discuss the I/O services provided by the operating system and the embodiment of these services in the application I/O interface. Then, we explain how the operating...

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This chapter is primarily concerned with issues surrounding file storage and access on the most common secondary-storage medium, the disk. We explore ways to structure file use, to allocate disk space, to recover freed space, to track the locations of data, and to interface other parts of the operating system to secondary storage. Performance issues are considered throughout the chapter.

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In this chapter, we consider the various aspects of files and the major directory structures. We also discuss the semantics of sharing files among multiple processes, users, and computers. Finally, we discuss ways to handle file protection, necessary when we have multiple users and we want to control who may access files and how files may be accessed.

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Lecture Operating system concepts (Sixth ed) - Chapter 15: Network structures. The main contents of this chapter include all of the following: Background, topology, network types, communication, communication protocol, robustness, design strategies.

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Chapter 17 examines various mechanisms for process synchronization and communication, as well as methods for dealing with the deadlock problem, in a distributed environment. In addition, since a distributed system may suffer from a variety of failures that are not encountered in a centralized system, we also discuss here the issue of failure in a distributed system.

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The various processes in an operating system must be protected from one another’s activities. For that purpose, various mechanisms exist that can be used to ensure that the files, memory segments, CPU, and other resources can be operated on by only those processes that have gained proper authorization from the operating system. In this chapter, we examine the problem of protection in great detail and develop a unifying model for implementing...

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