Question

1.What are the four components of a process? What is the term that describes saving the state of one process, and restoring the state of another?

2.Draw and Explain function of Process Control Block(PCB).

3.      Explain 5 State process model, how it differ from 3 state Model. Which model is better, justify your answer

Answer 1

1)

Stack, data, text, and heap memory.

Context switching

2)

representation of a process in the operating system. It contains information associated with that process.

Process state, program counter, CPU registers, CPU-scheduling information, memory-management information, accounting information, and I/O status information.

Role of process control block

• At any instance, a process will be having various information associated with it like identifier, state, priority, program counters, memory pointers, accounting information etc. Such information are stored in a data structure called as Process Control block (PCB).
• It is an important tool that helps the OS support multiple processes and provide for multiprocessing.
• It contains sufficient information such that if an interrupt occurs, the process can begin from the point where it left later as if nothing had happened.
• The blocks are read and/or modified by every module in the OS including
  • Scheduling
  • Resource allocation
  • Interrupt processing
  • Performance monitoring and analysis
• It can be said that the process control block defines the state of OS.
• However, there comes the issue of Security; a bug in a single routine say the interrupt handler could damage the PCB which in turn can make it difficult for OS to manage the affected process.
• Changes made to the Process control block (like semantics or design changes) can affect various modules.
• 

3)

Five State Process Model

The states in the five state process models are:

1) New: The process has not yet been loaded into main memory.

2) Ready: the process is now prepared to execute when given the opportunity.

3) Running: the process is currently being executed.

4) Blocked: Process that is waiting for some event to occur.

5) Exit: Process is released from main memory because it has halted or aborted.

I suggest 5 state model rather than 3 state..model because there are more advantages

Concept of multi programming.

Clear track of process functionalities