操作系统原理ppt课件

,Click to edit Master title style,3.,1,Operating System,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,Chapter 3:Operating-System Structures,System Components,Operating System Services,System Calls,System Programs,System Structure,Virtual Machines,System Design and Implementation,System Generation,Operating System,Chapter 3:Operating-System S,Common System Components,Process Management,Main Memory Management,File Management,I/O System Management,Secondary Management,Networking,Protection System,Command-Interpreter System,Operating System,Common System ComponentsProces,Process Management,A,process,is a program in execution.A process needs certain resources,including CPU time,memory,files,and I/O devices,to accomplish its task.,The operating system is responsible for the following activities in connection with process management.,Process creation and deletion.,process suspension and resumption.,Provision of mechanisms for:,process synchronization,process communication,Operating System,Process ManagementA process is,Main-Memory Management,Memory is a large array of words or bytes,each with its own address.It is a repository of quickly accessible data shared by the CPU and I/O devices.,Main memory is a volatile storage device.It loses its contents in the case of system failure.,Operating System,Main-Memory ManagementMemory i,The operating system is responsible for the following activities in connections with memory management:,Keep track of which parts of memory are currently being used and by whom.,Decide which processes to load when memory space becomes available.,Allocate and deallocate memory space as needed.,Operating System,The operating system is respon,File Management,A file is a collection of related information defined by its creator.Commonly,files represent programs(both source and object forms)and data.,The operating system is responsible for the following activities in connections with file management:,File creation and deletion.,Directory creation and deletion.,Support of primitives for manipulating files and directories.,Mapping files onto secondary storage.,File backup on stable(nonvolatile)storage media.,Operating System,File ManagementA file is a col,I/O System Management,The I/O system consists of:,A buffer-caching system,A general device-driver interface,Drivers for specific hardware devices,Operating System,I/O System ManagementThe I/O s,Secondary-Storage Management,Since main memory(,primary storage,)is volatile and too small to accommodate all data and programs permanently,the computer system must provide,secondary storage,to back up main memory.,Operating System,Secondary-Storage ManagementSi,Most modern computer systems use disks as the principle on-line storage medium,for both programs and data.,The operating system is responsible for the following activities in connection with disk management:,Free space management,Storage allocation,Disk scheduling,Operating System,Most modern computer systems u,Command-Interpreter System,Many commands are given to the operating system by control statements which deal with:,process creation and management,I/O handling,secondary-storage management,main-memory management,file-system access,protection,networking,Operating System,Command-Interpreter SystemMany,Command-Interpreter System(Cont.),The program that reads and interprets control statements is called variously:,command-line interpreter,shell(in UNIX),Its function is to get and execute the next command statement.,Operating System,Command-Interpreter System(Co,Operating System Services,Program execution system capability to load a program into memory and to run it.,I/O operations since user programs cannot execute I/O operations directly,the operating system must provide some means to perform I/O.,File-system manipulation program capability to read,write,create,and delete files.,Operating System,Operating System ServicesProgr,Communications exchange of information between processes executing either on the same computer or on different systems tied together by a network.Implemented via,shared memory,or,message passing,.,Error detection ensure correct computing by detecting errors in the CPU and memory hardware,in I/O devices,or in user programs.,Operating System,Communications exchange of i,Additional Operating System Functions,Additional functions exist not for helping the user,but rather for ensuring efficient system operations.,Resource allocation allocating resources to multiple users or multiple jobs running at the same time.,Accounting keep track of and record which users use how much and what kinds of computer resources for account billing or for accumulating usage statistics.,Protection ensuring that all access to system resources is controlled.,Operating System,Additional Operating System Fu,System Calls,System calls provide the interface between a running program and the operating system.,Generally available as assembly-language instructions.,Languages