TAILIEUCHUNG - Bài giảng Hệ điều hành nâng cao (Operating System-OS): Chương 8 - Phan Vĩnh Thuần
Chương 8 - process synchronization. Bài giảng gồm có những nội dung chính sau: Multiprocessors, multicomputers, distributed systems, multiprocessor systems, multiprocessor hardware, multiprocessor OS types,. | Chapter 3. IO Management OBJECTIVES • Explore the structure of an operating system's I/O subsystem. • Discuss the principles of I/O hardware and its complexity. • Provide details of the performance aspects of I/O hardware and software. 1. I/O System . Overview The control of devices connected to the computer is a major concern of operating-system designers. I/O devices vary so widely in their function and speed (consider a mouse, a hard disk, and a CD-ROM jukebox), varied methods are needed to control them. These methods form the I/O subsystem of the kernel, which separates the rest of the kernel from the complexities of managing I/O devices. The basic I/O hardware elements, such as ports, buses, and device controllers To encapsulate the details and oddities of different devices, the kernel of an operating system is structured to use device-driver modules. The device drivers present a uniform device access interface to the I/O subsystem, much as system calls provide a standard interface between the application and the operating system. . I/O Hardware Computers operate a great many kinds of devices. Most fit into the general categories of storage devices (disks, tapes), transmission devices (network cards, modems), and human-interface devices (screen, keyboard, mouse). Despite the incredible variety of I/O devices, though, we need only a few concepts to understand how the devices are attached and how the software can control the hardware. The device communicates with the machine via a connection point (or port)—for example, a serial port. A bus is a set of wires and a rigidly defined protocol that specifies a set of messages that can be sent on the wires. A controller is a collection of electronics that can operate a port, a bus, or a device. How can the processor give commands and data to a controller to accomplish an I/O transfer? The short answer is that the controller has one or more registers for data and control signals. The processor communicates with .
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