UGC NET · PAPER 2
UGC NET Paper 2 Computer Science – Operating Systems PYQ: I/O Systems, Device Management & Threads
Q1.
Arrange the following levels of interrupt protection within the Linux Kernel in order of increasing priority:
(A) user mode programs
(B) bottom half interrupt handlers
(C) kernel system service routines
(D) top half interrupt handlers
(A) user mode programs
(B) bottom half interrupt handlers
(C) kernel system service routines
(D) top half interrupt handlers
- (A) (A), (B), (D), (C)
- (B) (A), (C), (B), (D)
- (C) (A), (C), (D), (B)
- (D) (D), (A), (C), (B)
Q2.
Given below are two statements:
Statement (I): A thread is a dispatchable unit of work that does not execute sequentially and is not interruptible.
Statement (II): It is not possible to alter the behaviour of a thread by altering its context when the thread is suspended.
In light of the above statements, choose the most appropriate answer.
Statement (I): A thread is a dispatchable unit of work that does not execute sequentially and is not interruptible.
Statement (II): It is not possible to alter the behaviour of a thread by altering its context when the thread is suspended.
In light of the above statements, choose the most appropriate answer.
- (A) Both Statement I and Statement II are correct
- (B) Both Statement I and Statement II are incorrect
- (C) Statement I is correct but Statement II is incorrect
- (D) Statement I is incorrect but Statement II is correct
Q3.
Given below are an Assertion (A) and a Reason (R):
Assertion (A): I/O protection is ensured by a hardware trap.
Reason (R): I/O interrupts are caused by conditions such as I/O completion and device malfunction occurring within I/O devices.
In light of the above, choose the correct answer.
Assertion (A): I/O protection is ensured by a hardware trap.
Reason (R): I/O interrupts are caused by conditions such as I/O completion and device malfunction occurring within I/O devices.
In light of the above, choose the correct answer.
- (A) Both A and R are true and R is the correct explanation of A
- (B) Both A and R are true but R is NOT the correct explanation of A
- (C) A is true but R is false
- (D) A is false but R is true
Q4.
Given below are two statements:
Assertion A: A process involves a library function to create a thread.
Reason R: The threads make system calls to convey their resource and I/O requirements to the Kernel.
Assertion A: A process involves a library function to create a thread.
Reason R: The threads make system calls to convey their resource and I/O requirements to the Kernel.
- (A) Both A and R are true and R is the correct explanation of A
- (B) Both A and R are true but R is NOT the correct explanation of A
- (C) A is true but R is false
- (D) A is false but R is true
Q5.
In a multi-user operating system, requests for a particular resource arrive at an average rate of 20 per hour (a Poisson arrival process). What is the probability that no request is made in a 45-minute interval?
- (A) e^(-15)
- (B) e^(-5)
- (C) 1 - e^(-5)
- (D) 1 - e^(-10)
Q6.
Given below are two statements:
Assertion A: A process involves a library function to create a thread.
Reason R: The threads make system calls to convey their resource and I/O requirements to the Kernel.
Assertion A: A process involves a library function to create a thread.
Reason R: The threads make system calls to convey their resource and I/O requirements to the Kernel.
- (A) Both A and R are true and R is the correct explanation of A
- (B) Both A and R are true but R is NOT the correct explanation of A
- (C) A is true but R is false
- (D) A is false but R is true
Q7.
In Linux Operating system, when ________ is invoked, it is passed a set of flags that determine how much sharing is to take place between the parent and child tasks.
- (A) fork()
- (B) clone()
- (C) pthread()
- (D) thread()
Q8.
User level threads are threads that are visible to the programmer and are unknown to the kernel. The operating system kernel supports and manages kernel level threads. Three different models relate user and kernel level threads:
Statement (A): (i) The many-to-one model maps many user threads to one kernel thread. (ii) The one-to-one model maps one user thread to one kernel thread. (iii) The many-to-many model maps many user threads to a smaller or equal number of kernel threads.
Statement (B): (i) The many-to-one model maps many kernel threads to one user thread. (ii) The one-to-one model maps one kernel thread to one user thread. (iii) The many-to-many model maps many kernel threads to a smaller or equal number of user threads.
Which of the following is true?
Statement (A): (i) The many-to-one model maps many user threads to one kernel thread. (ii) The one-to-one model maps one user thread to one kernel thread. (iii) The many-to-many model maps many user threads to a smaller or equal number of kernel threads.
Statement (B): (i) The many-to-one model maps many kernel threads to one user thread. (ii) The one-to-one model maps one kernel thread to one user thread. (iii) The many-to-many model maps many kernel threads to a smaller or equal number of user threads.
Which of the following is true?
- (A) (A) is true; (B) is false
- (B) (A) is false; (B) is true
- (C) Both (A) and (B) are true
- (D) Both (A) and (B) are false
Q9.
One of the disadvantages of user-level threads compared to kernel-level threads is:
- (A) If a user-level thread executes a system call, all threads in that process are blocked.
- (B) Scheduling is application dependent.
- (C) Thread switching doesn't require kernel mode privileges.
- (D) Library procedures for thread management are local procedures.
Q10.
Match List I with List II regarding operating system I/O management.
List I: (a) Device controller (b) Device driver (c) Interrupt handler (d) Kernel I/O subsystem
List II: (i) Extracts information from the controller's registers and stores it in a data buffer (ii) Performs I/O scheduling (iii) Performs the actual data transfer between the device and memory (iv) Processes/initiates the I/O request
Choose the correct answer from the options given below.
List I: (a) Device controller (b) Device driver (c) Interrupt handler (d) Kernel I/O subsystem
List II: (i) Extracts information from the controller's registers and stores it in a data buffer (ii) Performs I/O scheduling (iii) Performs the actual data transfer between the device and memory (iv) Processes/initiates the I/O request
Choose the correct answer from the options given below.
- (A) (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
- (B) (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
- (C) (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
- (D) (a)-(i), (b)-(iii), (c)-(iv), (d)-(ii)