PROCESSES AND THREADS

11.What is schedulers?

A process migrates between the various scheduling queues through out its life time. The OS must select processes from these queues in some fashion. This selection process is carried out by a scheduler.

12.What are the use of job queues, ready queues and device queues?

As a process enters a system they are put in to a job queue. This queues consist of all jobs in the system. The processes that are residing in main memory and are ready and waiting to execute are kept on a list called ready queue. The list of processes waiting for a particular I/O devices kept in the device queue.

13.What is meant by context switch?

Switching the CPU to another process requires saving the state of the old process and loading the saved state for the new process. This task is known as context switch.

14.What is independent process?

A process is independent it cannot affect Or be affected by the other processes executing in the system. Any process does not share data with other process is a independent process.

15.What is co-operative process?

A process is co-operating if it can affect or be affected by the other processes executing in the system. Any process that share data with other process is a co-operating process.

16. What are the benefits OS co-operating process?

**Information sharing. 

** Computation speed up. **Modularity. 

**Convenience.

17.How can a user program  disturb the normal operation of the system?

**Issuing illegal I/O operation.

**By accessing memory locations with in the OS itself. **Refusing to relinquish the CPU.

18.State the advantage of multiprocessor system?

#Increased throughput. #Economy of scale. #Increased reliability.

19. What is the use of inter process communication.

Inter process communication provides a mechanism to allow the co-operating process to

communicate with each other and synchronies their actions without sharing the same address space. It is provided a message passing system.

20.What is a thread?

A thread otherwise called a lightweight process (LWP) is a basic unit of CPU utilization, it comprises of a thread id, a program counter, a register set and a stack. It shares with other threads belonging to the same process its code section, data section, and operating system resources such as open files and signals.