12 process control blocks
- 1. Understand Process Management : Process Control Blocks HOME PREVIOUS TOPIC NEXT PREVIOUS QUESTION PAPERS FOR OS CPP TUTORIALS 1
- 2. Recap In the last class, you have learnt • Process, Process State Diagram • Sequential Process 2
- 3. Objectives On completion of this period, you would be able to know • Understand the Structure of Process Control Block 3
- 4. Process Control Block • Each process is represented in the operating system by a Process control block ( PCB ) • PCB is also called a Task Control Block • PCB contains specific information associated to a process • PCB consisting of various information is shown in next slide 4
- 5. Process Control Block ( PCB ) 5
- 6. Process Control Block ( PCB ) Process control block consists of following information: • Pointer • Process state • Process number • Program counter • CPU Register • CPU-Scheduling Information • Memory-Management Information • Accounting Information • I/O status Information 6
- 7. Process Control Block ( PCB ) Pointer • It contains the address of another process which is present in the ready queue Process State •It contains information about the state of the process i.e., •New •Ready •Running •Waiting •Halted 7
- 8. Process Control Block ( PCB ) Program counter •The address of the next instruction to be executed CPU Registers •The registers vary in no. and type depending on the type of computer architecture, they include: •Accumulators, index registers, stack pointers and general purpose registers 8
- 9. Process Control Block ( PCB ) CPU scheduling information • This information includes – Process priority – Pointer to scheduling queues – Other scheduling parameters Memory management information • This information includes – Value of base and limit registers – Page tables – Segment tables 9
- 10. Process Control Block ( PCB ) Accounting information: •This information includes •Amount of CPU and real time used •Time limits •Account numbers •Job or Process no.s etc. I/O status information •This information includes •List of I/O devices allocated to the process •List of open files, etc 10
- 11. CPU Switch from Process to Process Process 0 Process 1 executing Save state into PCB0 idle Reload state from PCB1 idle Interrupt or system call executing Save state into PCB1 idle Reload state from PCB0 executing 11
- 12. Summary In this class, you have learnt • The structure of a Process Control Block • Various pieces of information associated with a specific process • The sequence of activities that occur when CPU switches from process to process 12
- 13. Quiz 1. PCB stands for process control board a) True b) False 2.Process control block does not contain any information about process state . a) True b) False 3.The information stored in a PCB varies from process to process. a) True b) False 13
- 14. Frequently Asked Questions 1. Explain the structure of a process control block with the help of a diagram. 14
- 15. Other subject materials • Web designing • Micro processors • C++ tutorials • java home