TAILIEUCHUNG - Bài giảng Hệ điều hành nâng cao - Chapter 13: I/O Systems
Bài giảng Hệ điều hành nâng cao - Chapter 13: I/O systems trình bày về I/O hardware, application I/O interface, kernel I/O subsystem, transforming I/O requests to hardware operations, STREAMS, performance. | Chapter 13: I/O Systems 1 Chapter 13: I/O Systems I/O Hardware Application I/O Interface Kernel I/O Subsystem Transforming I/O Requests to Hardware Operations STREAMS Performance 2 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 3 Overview I/O management is a major component of operating system design and operation Important aspect of computer operation I/O devices vary greatly Various methods to control them Performance management New types of devices frequent Ports, busses, device controllers connect to various devices Device drivers encapsulate device details Present uniform device-access interface to I/O subsystem I/O Hardware Incredible variety of I/O devices Storage Transmission Human-interface Common concepts – signals from I/O devices interface with computer Port – connection point for device Bus - daisy chain or shared direct access Controller (host adapter) – electronics that operate port, bus, device Sometimes integrated Sometimes separate circuit board (host adapter) Contains processor, microcode, private memory, bus controller, etc Some talk to per-device controller with bus controller, microcode, memory, etc 5 A Typical PC Bus Structure 6 I/O Hardware (Cont.) I/O instructions control devices Devices usually have registers where device driver places commands, addresses, and data to write, or read data from registers after command execution Data-in register, data-out register, status register, control register Typically 1-4 bytes, or FIFO buffer Devices have addresses, used by Direct I/O instructions Memory-mapped I/O Device data and command registers mapped to processor address space Especially for large address spaces (graphics) Device I/O Port Locations on PCs (partial) 8 Polling For each byte of I/O Read busy bit from status register until 0 Host sets read or write bit and if write copies data into
đang nạp các trang xem trước
