lec3_proc

lec3_proc - Announcement CSE120 Principles of Operating...

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1 CSE120 Principles of Operating Systems Prof Yuanyuan (YY) Zhou Lecture 3: Process Sept 29th, 2010 9/29/2010 CSE120 - Operating Systems, Yuanyuan Zhou 2 Announcement Project groups When you have chosen groups, send your group info to Matt Review: Interrupt Vector Table 9/29/2010 CSE120 - Operating Systems, Yuanyuan Zhou 3 9/29/2010 CSE120 - Operating Systems, Yuanyuan Zhou 4 Processes This lecture starts a class segment that covers processes, threads, and synchronization These topics are perhaps the most important in CSE120 You can rest assured that they will be covered in the exams Today’s topics are processes and process management What are the units of execution? How are those units of execution represented in the OS? What are the possible execution states of a process? How does a process move from one state to another?
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2 9/29/2010 CSE120 - Operating Systems, Yuanyuan Zhou 5 Users, Programs Users have accounts on the system Users launch programs Many users may launch same program One user may launch many instances of the same program Then what is a process? 9/29/2010 CSE120 - Operating Systems, Yuanyuan Zhou 6 The Process The process is the OS abstraction for execution It is the unit of execution It is the dynamic execution context of a program A process is sometimes called a job or a task Real life analogy? 9/29/2010 CSE120 - Operating Systems, Yuanyuan Zhou 7 Analogy Program: steps for attending the lecture Step1: walk to Warren lecture Step2: enter 205 Step3: find a seat Step4: listen and take notes (or sleep) Process: attending the lecture Action You are all in the middle of a process 9/29/2010 CSE120 - Operating Systems, Yuanyuan Zhou 8 Windows Task Manager
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3 9/29/2010 CSE120 - Operating Systems, Yuanyuan Zhou 9 Unix Example: ps 9/29/2010 CSE120 - Operating Systems, Yuanyuan Zhou 10 Process State A process has an execution state that indicates what it is currently doing Running : Executing instructions on the CPU It is the process that has control of the CPU How many processes can be in the running state simultaneously? Ready : Waiting to be assigned to the CPU Ready to execute, but another process is executing on the CPU Waiting : Waiting for an event, e.g., I/O completion It cannot make progress until event is signaled (disk completes) As a process executes, it moves from state to state Unix “ps”: STAT column indicates execution state 9/29/2010 CSE120 - Operating Systems, Yuanyuan Zhou 11 Process State Graph New Ready Running Waiting Terminated Create Process Process Exit I/O, Page Fault, etc. I/O Done
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This note was uploaded on 12/09/2010 for the course CSE CSE 120 taught by Professor Yuanyuanzhou during the Spring '10 term at UCSD.

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lec3_proc - Announcement CSE120 Principles of Operating...

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