operatingsystem《操作系统》ch01-introdu.ppt
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1、Operating System,Instructor:Hou Mengbo(Dr.&Associate Prof.)Office:Institute of Information Security.Specialist Building Rm.324,Software Campus,SDU,Computer Science&Technology School of ShanDong University&Software College,Course No:0303100111,O,Introduction,Textbook:Operating System Concepts(7th Edi
2、tion)-A.Silberschatz Fri.8:00-10:00am Q&A Time:Tues.15:30-16:30pm Requirements for success:Read the book in detailDo well on the homework and experimentsDo well on the final exam Attend class and participate,Supplements,Scope:Chap.1-Chap.15 Slides Source:or from me _Reference(Bibliographies):计算机操作系统
3、 汤子赢编著 西安电子科技大学出版社出版 实用操作系统概念 Applied Operating System Concepts Higher Education Press(English Edition)Notes:All the slides used in this course is adopted from the web site with some modification,and copyright belongs to the authors of this book.,Outline of the Textbook,Only 5 parts will be covered:
4、Overview(C1-2)what it is/what it can do/how it designed and constructed/historyProcess management(C3-7)process&concurrentMemory management(C8-9)allocation/Virtual Memory Storage management(C10-13)file system/mass storage/IOProtection&security(C14-15)Distributed systems,special-purpose systems and ot
5、hers will be omitedCases Study Linux/windows2000/windows XP/FreeBSD/Mach/Nachos omited,Chapter 1:Introduction,Chapter Objectives,To provide a grand tour of the major operating systems componentsTo provide coverage of basic computer system organization,Content Overview,What Operating Systems DoComput
6、er-System OrganizationComputer-System ArchitectureOperating-System StructureOperating-System OperationsProcess ManagementMemory ManagementStorage ManagementProtection and Security,1.1 What Operating Systems Do,A program that acts as an intermediary between a user of a computer and the computer hardw
7、are.Operating system goals:Execute user programs and make solving user problems easier.Make the computer system convenient to use.Use the computer hardware in an efficient manner.,Computer System Structure,Computer system can be divided into 4 components(see Fig.below):Hardware provides basic comput
8、ing resourcesCPU,memory,I/O devicesOperating systemControls and coordinates use of hardware among various applications and usersApplication programs define the ways in which the system resources are used to solve the computing problems of the usersWord processors,compilers,web browsers,database syst
9、ems,video gamesUsersPeople,machines,other computers,Four Components of a Computer System,Roles:Two views of Operating System,User view ease of use/performance/resource utilizationSystem viewOS is a resource allocatorManages all resourcesDecides between conflicting requests for efficient and fair res
10、ource useOS is a control programControls execution of programs to prevent errors and improper use of the computer,Operating System Definition,No universally accepted definition“Everything a vendor ships when you order an operating system”is good approximation,But varies wildly“The one program runnin
11、g at all times on the computer”is the kernel.Everything else is either a system program(ships with the operating system)or an application programOur definition:Software sets:Resource management;Control programs;Convenient to users;,1.2 Computer System Organization,Basic OrganizationOne or more CPUs,
12、device controllers connect through common bus providing access to shared memoryConcurrent execution of CPUs and devices competing for memory cycles,Computer Startup,bootstrap program is loaded at power-up or rebootTypically stored in ROM or EPROM,generally known as firmwareInitializes all aspects of
13、 systemLoads operating system kernel and starts executionInterrupt drivenHardware InterruptsSoftware Interrupts(system call,or monitor call),Computer-System Operation,I/O devices and the CPU can execute concurrently.Each device controller is in charge of a particular device type.Each device controll
14、er has a local buffer.CPU moves data from/to main memory to/from local buffersI/O is from the device to local buffer of controller.Device controller informs CPU that it has finished its operation by causing an interrupt from hardware or software.,Common Functions of Interrupts,Interrupt transfers co
15、ntrol to the interrupt service routine generally,through the interrupt vector,which contains the addresses of all the service routines.Interrupt architecture must save the address of the interrupted instruction.Incoming interrupts are disabled while another interrupt is being processed to prevent a
16、lost interrupt.A trap is a software-generated interrupt caused either by an error or a user request(system call).An operating system is interrupt driven.,Interrupt Handling,The operating system preserves the state of the CPU by storing registers and the program counter.Determines which type of inter
17、rupt has occurred:pollingvectored interrupt systemSeparate segments of code determine what action should be taken for each type of interrupt,Interrupt Timeline,Storage Structure,Main memory only large storage media that the CPU can access directly.RAM(small&volatile)Secondary storage extension of ma
18、in memory that provides large nonvolatile storage capacity.such as:Magnetic disks rigid metal or glass platters covered with magnetic recording material Disk surface is logically divided into tracks,which are subdivided into sectors.The disk controller determines the logical interaction between the
19、device and the computer.,Storage Hierarchy,Storage systems organized in hierarchy(see below).SpeedCostsizeVolatilityCaching copying information into faster storage system;main memory can be viewed as a last cache for secondary storage.,Storage-Device Hierarchy,I/O Structure,Storage is only one of ma
20、ny types of I/O devices within a computer.CPU-Device Driver-Common Bus-Device Controller-Device,Direct Memory Access(DMA)Structure,Used for high-speed I/O devices able to transmit information at close to memory speeds.Device controller transfers blocks of data from buffer storage directly to main me
21、mory without CPU intervention.Only one interrupt is generated per block,rather than the one interrupt per byte.,1.3 Computer System Architecture,Single-Processor SystemsMultiprocessor Systems Terms:graceful degradation平稳退化Increased throughput Fault tolerant Economy of scale.Increased reliability(fau
22、lt tolerant)asymmetric multiprocessing(AMP)/symmetric multiprocessing(SMP)Clustered Systemscomputers share storage and are closely linked via a local-area network(LAN),to provide high-availability service,1.4 Operating System Structure,Multiprogramming needed for efficiencySingle user cannot keep CP
23、U and I/O devices busy at all timesMultiprogramming organizes jobs(code and data)so CPU always has one to executeA subset of total jobs in system is kept in memoryOne job selected from job pool on the disk and run via job schedulingWhen it has to wait(for I/O for example),OS switches to another jobT
24、imesharing(multitasking)is logical extension in which CPU switches jobs so frequently that users can interact with each job while it is running,creating interactive computingResponse time should be 1 secondEach user has at least one program executing in memory processIf several jobs ready to run at
25、the same time CPU schedulingIf processes dont fit in memory,swapping moves them in and out to runVirtual memory allows execution of processes not completely in memory,Memory Layout for Multiprogrammed System,1.5 Operating-System Operations,Interrupt driven by hardwareSoftware error or request create
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