OPERATING SYSTEM

A process is moved to the ready state when its time quantum expires.
(i) Blocked
(ii) New
(iii) Running
(iv) Suspended

Which of the following is also called job scheduler?
(i) DMA controller
(ii) Short-term scheduler
(iii) CPU scheduler
(iv) Long-term scheduler

Scheduling a process from ready Queue to CPU is done by
(i) Short term scheduler
(ii) Midle term scheduler
(iii) Long term scheduler
(iv) Dispatcher

Define jacketing.

Which process can be affected by other processes executing in the system?
(i) Independent process
(ii) Co-operative process
(iii) Dependent Process
(iv) child process

______ is a technique of improving the priority of process waiting in queue for CPU allocation.
(i) starvation
(ii) Ageing
(iii) Revocation
(iv) Relocation

The processes that are residing in main memory and are ready and waiting to execute are kept on a list called
(i) job queue
(ii) ready queue
(iii) execution queue
(iv) process queue

Fork is used to
(i) dispatch a task
(ii) create a new job
(iii) create a new process
(iv) increase the priority of a task

When the event for which a thread is blocked occurs?
(i) Thread moves to the ready queue
(ii) Thread remains blocked
(iii) Thread completes
(iv) A new thread is provided

Waiting Time is calculated as
(i) Turnaround Time - Burst Time
(ii) Turnaround Time - Arrival Time
(iii) Completion Time - Arrival Time
(iv) Completion Time - Burst Time

Define Thread? List some of the benefits of multithreading. Demonstrate the three methods to implement Threads.

Explain the concept of a process. With the help of a state transition diagram, discuss the various process states.

What is process control block?

Explain the difference among short-term, medium-term and long-term scheduling.

Describe the differences among short term, medium-term, and long-term scheduling.

Assume the following workload in a system:

Process	Arrival Time	Burst Time
P0	1	3
P1	0	6
P2	3	2
P3	4	7
P4	2	8
P5	6	5

Illustrating the execution of these job using Round Robin Scheduling algorithm calculate when given Time Quantum=3 :
(i) Average Turn Around Time
(ii) Average Waiting Time

Consider the following process:

Process	Arrival Time	Burst Time
P1	0.0	7
P2	2.0	4
P3	4.0	1
P4	5.0	4

Considering non-preemptive and preemptive SJF algorithm, find out average waiting time and average turnaround time in both cases.

Differentiate between:
(i) User level Thread and Kernel level Thread.
(ii) Preemptive scheduling and Non-preemptive scheduling
(iii) Contiguous and Indexed allocation method

Including the initial parent process, how many processes are created by the program shown below?

#include<stdio.h>
#include<unistd.h>
int main()
{
    /*fork a child process */
    fork();
    /* fork another child process*/
    fork();
    /* and fork another*/
    fork();
    return 0;
}

Describe the differences among short-term, medium-term, and long-term scheduling.

What are the differences between user-level threads and kernel-level threads? Under what circumstances is one type better than the other?

An airline reservation system, using a centralized database service, processes user requests concurrently. Is it preferable to use threads rather than processes in this system? Give reasons for your answer.

What resources are used when a thread is created? How do they differ from those used when a process is created?

Consider a system running ten I/O-bound tasks and one CPU-bound task. Assume that the I/O-bound tasks issue an I/O operation once for every millisecond of CPU computing and that each I/O operation takes 10 milliseconds to complete. Also assume that the context-switching overhead is 0.1 millisecond and that all processes are long-running tasks. Describe the CPU utilization for round-robin scheduler when:
(i) the time quantum is 1 millisecond;
(ii) the time quantum is 10 milli-seconds.

Describe the actions taken by a kernel to context switch between kernel-level threads.

Five batch jobs, A through E, arrive at a computer center at essentially the same time. They have an estimated running time of 15, 9, 3, 6 and 12 minutes, respectively. Their (externally defined) priorities are 6, 3, 7, 9 and 4, respectively, with a lower value corresponding to a higher priority.
For each of the following scheduling algorithms, determine the waiting time for each process and the average waiting for all jobs. Ignore process switching overhead. Explain how you arrived at your answers. In the last three cases, assume that only one job at a time runs until it finishes and that all jobs are completely processor bound:
(a) Priority scheduling
(b) FCFS (run in order 15, 9, 3, 6 and 12)
(c) Shortest job first

What is a thread?

How is thread different from a process?

What resources are used when a thread is created?

Write short note on: Process Control Block