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Bài giảng Hệ điều hành nâng cao - Chapter 1: Introduction

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Bài giảng Hệ điều hành nâng cao - Chapter 1: Introduction

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  1. Chapter 1: Introduction Operating System Concepts – 8th Edition Operating System Concepts – 8th Edition 1.1 Silberschatz, Galvin and Gagne ©2009
  2. Chapter 1: Introduction s What Operating Systems Do s Computer-System Organization s Computer-System Architecture s Operating-System Structure s Operating-System Operations s Process Management s Memory Management s Storage Management s Protection and Security s Distributed Systems s Special-Purpose Systems s Computing Environments s Open-Source Operating Systems Operating System Concepts – 8th Edition 1.2 Silberschatz, Galvin and Gagne ©2009
  3. Objectives s To provide a grand tour of the major operating systems components s To provide coverage of basic computer system organization Operating System Concepts – 8th Edition 1.3 Silberschatz, Galvin and Gagne ©2009
  4. What is an Operating System? s A program that acts as an intermediary between a user of a computer and the computer hardware s Operating system goals: q Execute user programs and make solving user problems easier q Make the computer system convenient to use q Use the computer hardware in an efficient manner Operating System Concepts – 8th Edition 1.4 Silberschatz, Galvin and Gagne ©2009
  5. Computer System Structure s Computer system can be divided into four components: q Hardware – provides basic computing resources 4 CPU, memory, I/O devices q Operating system 4 Controls and coordinates use of hardware among various applications and users q Application programs – define the ways in which the system resources are used to solve the computing problems of the users 4 Word processors, compilers, web browsers, database systems, video games q Users 4 People, machines, other computers Operating System Concepts – 8th Edition 1.5 Silberschatz, Galvin and Gagne ©2009
  6. Four Components of a Computer System Operating System Concepts – 8th Edition 1.6 Silberschatz, Galvin and Gagne ©2009
  7. What Operating Systems Do s Depends on the point of view s Users want convenience, ease of use q Don’t care about resource utilization s But shared computer such as mainframe or minicomputer must keep all users happy s Users of dedicate systems such as workstations have dedicated resources but frequently use shared resources from servers s Handheld computers are resource poor, optimized for usability and battery life s Some computers have little or no user interface, such as embedded computers in devices and automobiles Operating System Concepts – 8th Edition 1.7 Silberschatz, Galvin and Gagne ©2009
  8. Operating System Definition s OS is a resource allocator q Manages all resources q Decides between conflicting requests for efficient and fair resource use s OS is a control program q Controls execution of programs to prevent errors and improper use of the computer Operating System Concepts – 8th Edition 1.8 Silberschatz, Galvin and Gagne ©2009
  9. Operating System Definition (Cont.) s No universally accepted definition s “Everything a vendor ships when you order an operating system” is good approximation q But varies wildly s “The one program running at all times on the computer” is the kernel. Everything else is either a system program (ships with the operating system) or an application program. Operating System Concepts – 8th Edition 1.9 Silberschatz, Galvin and Gagne ©2009
  10. Computer Startup s bootstrap program is loaded at power-up or reboot q Typically stored in ROM or EPROM, generally known as firmware q Initializes all aspects of system q Loads operating system kernel and starts execution Operating System Concepts – 8th Edition 1.10 Silberschatz, Galvin and Gagne ©2009
  11. Computer System Organization s Computer-system operation q One or more CPUs, device controllers connect through common bus providing access to shared memory q Concurrent execution of CPUs and devices competing for memory cycles Operating System Concepts – 8th Edition 1.11 Silberschatz, Galvin and Gagne ©2009
  12. Computer-System Operation s I/O devices and the CPU can execute concurrently s Each device controller is in charge of a particular device type s Each device controller has a local buffer s CPU moves data from/to main memory to/from local buffers s I/O is from the device to local buffer of controller s Device controller informs CPU that it has finished its operation by causing an interrupt Operating System Concepts – 8th Edition 1.12 Silberschatz, Galvin and Gagne ©2009
  13. Common Functions of Interrupts s Interrupt transfers control to the interrupt service routine generally, through the interrupt vector, which contains the addresses of all the service routines s Interrupt architecture must save the address of the interrupted instruction s Incoming interrupts are disabled while another interrupt is being processed to prevent a lost interrupt s A trap is a software-generated interrupt caused either by an error or a user request s An operating system is interrupt driven Operating System Concepts – 8th Edition 1.13 Silberschatz, Galvin and Gagne ©2009
  14. Interrupt Handling s The operating system preserves the state of the CPU by storing registers and the program counter s Determines which type of interrupt has occurred: q polling q vectored interrupt system s Separate segments of code determine what action should be taken for each type of interrupt Operating System Concepts – 8th Edition 1.14 Silberschatz, Galvin and Gagne ©2009
  15. Interrupt Timeline Operating System Concepts – 8th Edition 1.15 Silberschatz, Galvin and Gagne ©2009
  16. I/O Structure s After I/O starts, control returns to user program only upon I/O completion q Wait instruction idles the CPU until the next interrupt q Wait loop (contention for memory access) q At most one I/O request is outstanding at a time, no simultaneous I/O processing s After I/O starts, control returns to user program without waiting for I/O completion q System call – request to the operating system to allow user to wait for I/O completion q Device-status table contains entry for each I/O device indicating its type, address, and state q Operating system indexes into I/O device table to determine device status and to modify table entry to include interrupt Operating System Concepts – 8th Edition 1.16 Silberschatz, Galvin and Gagne ©2009
  17. Direct Memory Access Structure s Used for high-speed I/O devices able to transmit information at close to memory speeds s Device controller transfers blocks of data from buffer storage directly to main memory without CPU intervention s Only one interrupt is generated per block, rather than the one interrupt per byte Operating System Concepts – 8th Edition 1.17 Silberschatz, Galvin and Gagne ©2009
  18. Storage Structure s Main memory – only large storage media that the CPU can access directly q Random access q Typically volatile s Secondary storage – extension of main memory that provides large nonvolatile storage capacity s Magnetic disks – rigid metal or glass platters covered with magnetic recording material q Disk surface is logically divided into tracks, which are subdivided into sectors q The disk controller determines the logical interaction between the device and the computer Operating System Concepts – 8th Edition 1.18 Silberschatz, Galvin and Gagne ©2009
  19. Storage Hierarchy s Storage systems organized in hierarchy q Speed q Cost q Volatility s Caching – copying information into faster storage system; main memory can be viewed as a cache for secondary storage Operating System Concepts – 8th Edition 1.19 Silberschatz, Galvin and Gagne ©2009
  20. Storage-Device Hierarchy Operating System Concepts – 8th Edition 1.20 Silberschatz, Galvin and Gagne ©2009
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