上海交通大学：《操作系统 Operating System》课程教学资源（课件讲稿）OS-process_Lec5

OPERATING SYSTEMS 1 龚玲 lgong@sjtu.edu.cn

OPERATING SYSTEMS 龚玲 lgong@sjtu.edu.cn 1

CHAPTER 3:PROCESSES Operating System Concepts with Java-7th Edition,Nov 15,2006 Silberschatz,Galvin and Gagne 2007

Operating System Concepts with Java – 7 th Edition, Nov 15, 2006 Silberschatz, Galvin and Gagne ©2007 CHAPTER 3: PROCESSES

CHAPTER 3:PROCESSES o Process Concept o Process Scheduling o Operations on Processes o Cooperating Processes o Inter process Communication o Communication in Client-Server Systems

CHAPTER 3: PROCESSES  Process Concept  Process Scheduling  Operations on Processes  Cooperating Processes  Inter process Communication  Communication in Client-Server Systems

REVIEW o Process o Process vs.Program o http://wenku.baidu.com/course/study/77fldcccda38376ba flfae94#665ea0c7aa00b52acfc7ca94

REVIEW  Process  Process vs. Program  http://wenku.baidu.com/course/study/77f1dcccda38376ba f1fae94#665ea0c7aa00b52acfc7ca94

PROCESS CONCEPT o An operating system executes a variety of programs: ·Batch system-jobs Time-shared systems-user programs or tasks o Textbook uses the terms job and process almost interchangeably o Process-a program in execution;process execution must progress in sequential fashion o A process includes: Information related to process ·stack ·data section ·text section 。heap

PROCESS CONCEPT  An operating system executes a variety of programs:  Batch system – jobs  Time-shared systems – user programs or tasks  Textbook uses the terms job and process almost interchangeably  Process – a program in execution; process execution must progress in sequential fashion  A process includes:  Information related to process  stack  data section  text section  heap

PROCESS IN MEMORY max stack heap data text 0

PROCESS IN MEMORY

GOALS FOR TODAY o Process o Operations on processes

GOALS FOR TODAY  Process  Operations on processes

PROCESS STATE o As a process executes,it changes state ● new:The process is being created running:Instructions are being executed waiting:The process is waiting for some event to occur ● ready:The process is waiting to be assigned to a process ● terminated:The process has finished execution

PROCESS STATE  As a process executes, it changes state  new: The process is being created  running: Instructions are being executed  waiting: The process is waiting for some event to occur  ready: The process is waiting to be assigned to a process  terminated: The process has finished execution

DIAGRAM OF PROCESS STATE new admitted interrupt exit terminated ready running 1/O or event completion scheduler dispatch 1/O or event wait waiting

DIAGRAM OF PROCESS STATE

Created Terminated Main Memory Running Ready Blocked Swapped out and waiting Swapped out and blocked Page file/swap space THE VARIOUS PROCESS STATES,DISPLAYED IN A STATE DIAGRAM,WITH ARROWS INDICATING POSSIBLE TRANSITIONS BETWEEN STATES -AS CAN BE SEEN.SOME PROCESSES ARE STORED IN MAIN MEMORY,AND SOME ARE STORED IN SECONDARY (VIRTUAL)MEMORY. Reference from http://en.wikipedia.org/wiki/Process_states

THE VARIOUS PROCESS STATES, DISPLAYED IN A STATE DIAGRAM, WITH ARROWS INDICATING POSSIBLE TRANSITIONS BETWEEN STATES - AS CAN BE SEEN, SOME PROCESSES ARE STORED IN MAIN MEMORY, AND SOME ARE STORED IN SECONDARY (VIRTUAL) MEMORY. Ready Reference from http://en.wikipedia.org/wiki/Process_states