操作系统概念ch01.ppt

Operating System Page * Process Management A process is a program in execution. It is a unit of work within the system. Program is a passive entity, process is an active entity. Process needs resources to accomplish its task CPU, memory, I/O, files Process termination requires reclaim of any reusable resources Operating System Page * Process Management Typically system has many processes, some user running concurrently on one or more CPUs Concurrency by multiplexing the CPUs among the processes / threads Single-threaded process has one program counter specifying location of next instruction to execute Process executes instructions sequentially, one at a time, until completion Multi-threaded process has one program counter per thread Operating System Page * Process Management Activities The operating system is responsible for the following activities in connection with process management: Creating and deleting both user and system processes Suspending and resuming processes Providing mechanisms for process synchronization Providing mechanisms for process communication Providing mechanisms for deadlock handling Operating System Page * Outlines for Chapter 1 What Operating Systems Do Computer-System Organization Operating-System Structure Operating-System Operations Process Management Memory Management Storage Management Protection and Security Operating System Page * Memory Management All data must be in memory before and after processing All instructions must be in memory in order to execute Memory management determines what is in memory Optimizing CPU utilization and computer response to users Memory management activities Allocating and de-allocating memory space as needed Keeping track of which parts of memory are currently being used and by whom Deciding which processes and data to move into and out of memory Operating System Page * Outlines for Chapter 1 What Operating Systems Do Computer-System Organization Operating-System Structure Operating-System Opera