CS6401 OS 2marks 16marks, Operating Systems Question Bank, OS Short Answers – IT 4th SEM Anna University


Anna University Regulation 2013 Information Technology (IT) CS6401 OS 2marks & 16marks for all 5 units are provided below. Download link for IT 4th SEM CS6401 Operating Systems Short answers, Question Bank are listed down for students to make perfect utilization and score maximum marks with our study materials.

CS6401- Operating System




1. Define process?
A process is more than a program code, which is sometime known as the text section. IT also includes the current activity, as represented by the value of the program counter and the processor’s registers.
2. What is meant by the state of the process?
The state of the process is defined in part by the current activity of that process. Each process may be in one of the following states.
x New: The process is being created.
x Running: Instruction are being executed
x Waiting: The process is waiting for some event to occur.
x Ready: The process is waiting to be assigned to a processor
x Terminated: The process has finished execution
3. Define process control block contain?
Each process is represented in the operating system by a process control block (PCB) – also called as task control block. The PCB simply serves as the repository for any information that may vary from process to process.
4. What does PCB contain?
x Process state
x Program counter
x CPU registers
x CPU scheduling information
x Memory management information
x Accounting information
5. What are the 3 different types of scheduling queues?
x Job Queue: As process enters the system they are put into job queue.
x Ready Queue: The processes that are residing in the main memory and are ready and waiting to execute are kept in the queue
x Device Queue: The list of processes waiting for particular I/O device is called a device queue.
6. Define schedulers?
A process migrates between the various scheduling throughout its lifetime. The operating system must select, for scheduling purposes, processes from these queues in some fashion. The selection process is carried out by the appropriate scheduler.
7. What are the types of scheduler?
Long term scheduler or job scheduler selects processes from the pool and load them into the memory for execution. Short term scheduler or CPU scheduler, select among the processes that are ready to execute and allocates the CPU to one of them.
8. Define critical section?
If a system consist on n processes {P0, P1,……., Pn-1}.Each process has a segment of code called a critical section, in which the process may be changing common variables, updating a table , writing a file. The important feature of this system is that, when one process is in its critical section, no other process is to be allowed to execute in its critical section.
9. What requirement is to be satisfied for a solution of a critical section problem?
A solution to the critical section problem must satisfy the following 3 requirements.
x Mutual exclusion: If process P1 is executing in its critical section, then no other processes can be executing in their critical sections.
x Progress: If no process is executing in its critical section and some processes wish to enter their critical sections, then only those processes that are not executing in their remainder section can participate in the decision on which will enter its critical section next, and this selection cannot be postponed indefinitely.

x Bounded waiting: There exists a bound on the number of times that other processes are allowed to enter their critical section after a process has made a request to enter its critical section and before that request is granted.
10. Define semaphores.
Semaphore is a synchronization toll. A semaphore S is an integer variable that apart from initialization is accessed only through 2 standard atomic operations.
x Wait
x Signal
CS6401 OS Unit 1 2marks & 16marks – Download Here
CS6401 OS Unit 2 2marks & 16marks – Download Here
CS6401 OS Unit 3 2marks & 16marks – Download Here
CS6401 OS Unit 4 2marks & 16marks – Download Here
CS6401 OS Unit 5 2marks & 16marks – Download Here
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Related Links
For CS6401 OS Previous Year Question Papers – Click here
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For CS6401 OS Lecture Notes – Click here
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