Sean Barker

Processes

1

Memory

I/O

Processor Processes, scheduling, synchronization

Allocation, protection, virtual memory

Disk management, filesystems, networking

Hardware OS Services

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Process Control Block (PCB)

2

Process Control Block (PCB)

Process State

PC

CPU registers

CPU scheduling info

List of open files

...

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Context Switching

3

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Process Execution States

4

Process State

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CPU Scheduling

5

Processes

CPU

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CPU and I/O Bursts

6

Process Behavior Long CPU burst

Short CPU burst Waiting for I/O

CPU-bound process

I/O-bound process

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Multilevel Feedback Queues

7

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CPU Scheduling Summary

First Come First Serve (FCFS)

Shortest Job First (SJF)

Shortest Remaining Time First (SRTF)

Round-Robin (RR)

Multilevel Feedback Queues (MLFQ)

... more advanced schedulers ...

8

Sean Barker

Threads

9

Sean Barker

Multithreaded Processes

10

Sean Barker

Thread APIs

11

POSIX Threads (pthreads): pthread_create(&tid, NULL, my_fun, &param); // thread runs my_fun

Windows Threads:ThreadHandle = CreateThread(NULL, 0, MyFun, &Param, 0, &ThreadID);

Java Threads:Thread t = new Thread(new MyRunnable(param));t.start(); // start the thread running MyRunnable.run()

Sean Barker

User-Level Threads

12