02_OS_Structures

02_OS_Structures - CSC 4103 - Operating Systems Fall 2009...

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1 CSC 4103 - Operating Systems Fall 2009 Tevfik Ko ! ar Louisiana State University August 27 th , 2009 Lecture - II OS Structures Announcements • TA Changed. New TA: Praveenkumar Kondikoppa Email: pkondi1@lsu.edu • All of you should be now in the class mailing list. Let me know if you haven’t received any messages yet. • Lecture notes are available on the course web site. 2 3 Roadmap • Major OS Components Corresponding OS Responsibilities • OS Design and Implementation Different Design Approaches • OS API System Calls Dual Mode of Operation 4 Computer System Organization • Computer-system operation One or more CPUs, device controllers connect through common bus providing access to shared memory Concurrent execution of CPUs and devices competing for memory cycles 5 Major OS Components ! Processes ! Memory management ! CPU Scheduling ! I/O Management 6 Processes " A process is the activity of executing a program Pasta for six boil 1 quart salty water stir in the pasta cook on medium until “al dente” serve Program Process CPU input data thread of execution
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7 Processes " It can be interrupted to let the CPU execute a higher-priority process Program Process First aid – Get the first aid kit – Check pulse – Clean wound with alcohol – Apply band aid CPU (changes hat to “doctor”) input data thread of execution 8 Processes " . . . and then resumed exactly where the CPU left off Pasta for six boil 1 quart salty water stir in the pasta cook on medium until “al dente” serve Program Process CPU (back to “chef”) input data thread of execution hmm. .. now where was I? 9 Processes job 1 job 2 job 3 job 1 . . . . . . job 3 job 1 . . . . . . job 4 job 1 " Multitasking gives the illusion of parallel processing (independent virtual program counters) on one CPU (a) Multitasking from the CPU’s viewpoint Pseudoparallelism in multitasking job 3 job 1 job 4 (b) Multitasking from the processes’ viewpoint = 4 virtual program counters process 1 process 2 process 3 process 4 Processes 10 Timesharing is logical extension in which CPU switches jobs so frequently that users can interact with each job while it is running, creating interactive computing Response time should be < 1 second Each user has at least one program loaded in memory and executing ! process 11 Processes " Operating System Responsibilities: The O/S is responsible for managing processes # the O/S creates & deletes processes # the O/S suspends & resumes processes # the O/S provides mechanisms for process synchronization # the O/S provides mechanisms for interprocess communication # the O/S provides mechanisms for deadlock handling 12 Memory Management " Main memory The storage hierarchy " # large array of words or bytes, each with its own address # repository of quickly accessible data shared by the CPU and I/O devices # volatile storage that loses its contents in case of system failure
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13 Performance of Various Levels of Storage • Movement between levels of storage hierarchy can be
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02_OS_Structures - CSC 4103 - Operating Systems Fall 2009...

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