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Nội dung Text: Bài giảng Hệ điều hành nâng cao - Chapter 1: Introduction
- Chapter 1: Introduction
Operating System Concepts – 8th Edition
Operating System Concepts – 8th Edition 1.1 Silberschatz, Galvin and Gagne ©2009
- 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
- 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
- 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
- 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
- Four Components of a Computer System
Operating System Concepts – 8th Edition 1.6 Silberschatz, Galvin and Gagne ©2009
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- Interrupt Timeline
Operating System Concepts – 8th Edition 1.15 Silberschatz, Galvin and Gagne ©2009
- 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
- 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
- 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
- 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
- Storage-Device Hierarchy
Operating System Concepts – 8th Edition 1.20 Silberschatz, Galvin and Gagne ©2009
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