The ppt is about process concept in operating system. Process states and process control block, along with context switching has been discussed in details.

1. Process Concepts
Dr. Kaushik Ghosh
University of Petroleum and Energy Studies

2. Process Definition
• Process is a program in execution
• Process execution must progress in sequential fashion
• Textbook uses the terms job and process almost interchangeably
• Batch system –> jobs
• Time-shared systems – >user programs or tasks

3. Schematic Representation of Process
Stack
Heap
Data
Text
Temporary Variables
Global Variables

4. Process State
• As a process executes, it changes state
• new: The process is being created.
• running: Instructions are being executed.
• waiting: The process is waiting for some event to occur.
• ready: The process is waiting to be assigned to a process.
• terminated: The process has finished execution.

5. Process State Diagram

6. Process Control Block (PCB)
Information associated with each process.
• Process state
• Program counter
• CPU registers
• CPU scheduling information
• Memory-management information
• Accounting information
• I/O status information
Manifestation of a process in operating system

7. Process Control Block (PCB)

8. CPU Switch From Process to Process

9. Process Scheduling Queues
• Job queue – set of all processes in the system.
• Ready queue – set of all processes residing in main memory,
ready and waiting to execute.
• Device queues – set of processes waiting for an I/O device.
• Process migration between the various queues.

10. Ready Queue and Various I/O Device Queues

11. Representation of Process Scheduling

12. Questions??
kghosh@ddn.upes.ac.in
Text: Operating System Principles (Silberschatz, Galvin and Gagne)