1. Process Management -Compiled for CSIT
(Ref: Modern Operating System, A.S Tannebum, Lecuture notes of Prof. Prashant Shenoy)

2. Topics to be Covered
2.1 Introduction to process 2.2 Interprocess Communication 2.3 Process Scheduling

3. What is Process Process Vs. Program? An abstraction of running process
A process is an instance of a computer program that is being executed.
Process Vs. Program?

5. Process Management
Provides ability to have (pseudo) concurrent operation even with only one CPU
Turns single CPU into Multiple Virtual CPUs
Multiprogramming achieved (not to be confused with multiprocessing)
Gives illusion of parallelism (pseudoparallelism)

6. What is Multiprogramming
Multiprogramming is a technique to execute number of programs simultaneously by a single processor.
In Multiprogramming, number of processes reside in main memory at a time.
The OS picks and begins to executes one of the jobs in the main memory.
If any I/O wait happened in a process, then CPU switches from that job to another job.
Hence CPU in not idle at any time.

7. Multiprogramming (Contd…):OS
Job 1
Job 2
Job 3
Job 4
Job 5
Figure dipicts the layout of multiprogramming system.
The main memory consists of 5 jobs at a time, the CPU executes one by one.
Advantages:
Efficient memory utilization
Throughput increases
CPU is never idle, so performance increases.

8. The Process Model
Runable software organized into number of sequential process
Process – An instance of a program, replete with registers, variables, and a program counter
Each process has it own virtual CPU
It has a program, input, output and a state
The real CPU switches back and forth from process to process
This rapid switching back and forth is called multiprogramming

9. Multiprogramming
(a) Multiprogramming of four programs. (b) Conceptual model of four independent, sequential processes. (c) Only one program is active at once.

10. Windows Snapshot

11. Process Creation Events which can cause process creation
System initialization.
Execution of a process creation system call by a running process.
A user request to create a new process.
Initiation of a batch job.

12. Process Termination Events which cause process termination:
Normal exit (voluntary).
Error exit (voluntary).
Fatal error (involuntary).
Killed by another process (involuntary).