Q1➡| NET June 2023 Consider the following table of arrival time and burst time for three processes P0.P1 P2:
The pre-emptive shortest job first scheduling algorithm is used. Scheduling is carried out only at arrival or completion of a process. What is the average waiting time for the three processes?
i ➥ 3 ms
ii ➥ 3.67 ms
iii ➥ 4.47 ms
iv ➥ 4 ms
Best Explanation: Answer: (ii) Explanation: Upload Soon
Q2➡| NET June 2023 Consider the following statements: S1: LRU page replacement algorithm suffers from the belady’s anomaly S2: Shortest remaining time first scheduling may cause starvations S3: Stack is shared by all threads in a process
i ➥ S1, S2 and S3 are true
ii ➥ S1, S3 false and S2 is true
iii ➥ S1, S2 are false and S3 is true
iv ➥ S1, S2 and S3 are false
Best Explanation: Answer: (ii) Explanation: Upload Soon
Q3➡|NET June 2023 Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. 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 requirement to the Kernel. In the light of the above statements, choose the correct answer from the options given below.
i ➥ Both A and R are true and R is the correct explanation of A
ii ➥ Both A and R are true but R is NOT the correct explanation of A
iii ➥ A is true but R is false
iv ➥ A is false but R is true
Best Explanation: Answer: (ii) Explanation: Upload Soon
Q4➡|NET June 2023 Given below are two statements: Which of the following statement/s is/are correct with respect to virtual memory
Statement I: Address translation is performed for every logical address used during the execution of a program. Statement II: A program can execute only when all of its components are loaded in the memory.
In the light of the above statements, choose the most appropriate answer from the options given below.
i ➥ Both Statement I and Statement II are correct
ii ➥ Both Statement I and Statement II are incorrect
iii ➥ Statement I is correct but Statement II is incorrect
iv ➥ Statement I is incorrect but Statement II is correct
Best Explanation: Answer: (iii) Explanation: Upload Soon
Q5➡|NET June 2023 At a particular time of computation, the value of a counting semaphore is 7. Then 20 p operations and ‘x’ V operations were completed on this semaphore. If the final value of semaphore is 5. x will be ?
i ➥ 15
ii ➥ 22
iii ➥ 18
iv ➥ 14
Best Explanation: Answer: (iii) Explanation: Upload Soon
Q7➡|NET June 2023 Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. A virtual memory system uses first-in first-out page replacement policy and allocates a fixed number of frames to a process Assertion A: Increasing number of page frames allocated to a process sometimes increases the page fault rate. Reason R: Some programs do not exhibit locality of reference.
In the light of the above statements, choose the correct answer from the options given below
i ➥ Both A and R are true and R is the correct explanation of A
ii ➥ Both A and R are true but R is NOT the correct explanation of A
iii ➥ A is true but R is false
iv ➥ A is false but R is true
Best Explanation: Answer: (ii) Explanation: Upload Soon
Q1➡| NET December 2022 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.
i ➥ Fork()
ii ➥ Clone()
iii ➥ Pthread()
iv ➥ Thread()
Best Explanation: Answer: (ii) Explanation: Upload Soon
Q2➡| NET December 2022 The main function of the microkernel is to provide a communication facility between the _______ program and the various _______ that are also running in user space .
i ➥ Virtual, processes
ii ➥ System, processes
iii ➥ Client, services
iv ➥ Virtual, services
Best Explanation: Answer: (iii) Explanation: Upload Soon
Q3➡| NET December 2022 Consider an operating system capable of loading and executing a single sequential user process at a time. The disk head scheduling algorithm used is first come first served (FCFS) . if FCFS is replaced by shorted seek time first (SSTF) and the vendor claims 50% better benchmark results. What is the expected improvement in the I/O performance of user programs?
i ➥ 50%
ii ➥ 100%
iii ➥ 25%
iv ➥ 0%
Best Explanation: Answer: (iv) Explanation: Upload Soon
Q4➡| NET December 2022 For the following set of processes scheduled using FCFS policy, determine the average waiting time. Assume that the processes arrived in the order P1, P2, P3, P4.
i ➥ 8
ii ➥ 16
iii ➥ 32
iv ➥ 48
Best Explanation: Answer: (ii) Explanation: Upload Soon
Q6➡| NET December 2022 Which of the following statements are true? (A) Shortest remaining time first scheduling may cause starvation (B) Preemptive scheduling may cause starvation (C) Round robin is better than FCFS in term of response time Choose the correct answer from the options given below:
i ➥ A only
ii ➥ B, C only
iii ➥ A, B only
iv ➥ A, B, C
Best Explanation: Answer: (iv) Explanation: Upload Soon
Q7➡| NET December 2022 In design protocol of critical section problem, each process must ask permission to enter critical section in ……… code, it then executes in the critical section; once it, finishes executes in the critical section it enters the …….. code. The process then enters the……..code.
i ➥ entry section, remainder section, exit section
ii ➥ entry section, exit section, remainder section
iii ➥ remainder section, entry section, exit section
iv ➥ remainder section, exit section, entry section
Best Explanation: Answer: (ii) Explanation: Upload Soon
Q9➡| NET December 2022 Select the correct order of events after power is initialized on a system: (A) Bootstrap loader is loaded from the disk (B) Kernel is loaded onto the memory (C) Firmware ROM loads boot block Choose the correct answer from the options given below:
i ➥ B, C, A
ii ➥ C, A, B
iii ➥ A, B, C
iv ➥ A, C, B
Best Explanation: Answer: (ii) Explanation: Upload Soon
Q10➡| NET December 2022 An OS follows round robin scheduling with time quantum of 4 ms. Assuming that the CPU is free now and there are 20 processes waiting in the ready queue, the maximum amount of time that a process waits before getting into the CPU is………….
i ➥ 80 ms
ii ➥ 76 ms
iii ➥ 84 ms
iv ➥ None of the above
Best Explanation: Answer: (ii) Explanation: Upload Soon
Q11➡| NET June 2022 If an operating system does not allow a child process to exist when the parent process has been terminated, this phenomenon is called as –
i ➥ Threading
ii ➥ Cascading termination
iii ➥ Zombie termination
iv ➥ Process killing
Best Explanation: Answer: (ii) Explanation: Upload Soon
Q12➡| NET June 2022 For the following page reference string 4, 3, 2, 1, 4, 3, 5, 4, 3, 2, 1, 5 the number of page faults that occur in Least Recently Used (LRU) page replacement algorithm with frame size 3 is
i ➥ 6
ii ➥ 8
iii ➥ 10
iv ➥ 12
Best Explanation: Answer: (iii) Explanation: Upload Soon
Q1➡| NET June 2021 Given memory access time as p nanoseconds and additional q nanoseconds for handling the page fault. What is the effective memory access time if a page fault occurs once for every 100 instructions?
Q2➡| NET June 2021 In a file allocation system, the following allocation schemes are used: A. Contiguous B. Indexed C. Linked allocation Which of the allocation scheme(s) given above will not suffer from external fragmentation? Choose the correct answer from the options given below:
Q4➡| NET June 2021 Consider the following 3 processes with the length of the CPU burst time given in milliseconds: What is the average waiting time for these processes if they are scheduled using preemptive shortest job first scheduling algorithm?
Q5➡| NET June 2021 Comprehension: Q5 to Q9 Read the following and answer the questions: Consider a machine with 16 GB main memory and 32-bits virtual address space, with page size as 4KB. Frame size and page size is same for the given machine. If a process of size 34KB is to be executed on this machine, then what will be the size of internal fragmentation for this process?
Q6➡| NET June 2021 Comprehension: Q5 to Q9 Read the following and answer the questions: Consider a machine with 16 GB main memory and 32-bits virtual address space, with page size as 4KB. Frame size and page size is same for the given machine. What is the size of page table for handling the given virtual address space, given that each page table entry is of size 2 bytes?
Q7➡| NET June 2021 Comprehension: Q5 to Q9 Read the following and answer the questions: Consider a machine with 16 GB main memory and 32-bits virtual address space, with page size as 4KB. Frame size and page size is same for the given machine. What is the minimum number of bits needed for the physical address?
Q8➡| NET June 2021 Comprehension: Q5 to Q9 Read the following and answer the questions: Consider a machine with 16 GB main memory and 32-bits virtual address space, with page size as 4KB. Frame size and page size is same for the given machine. The number of bits reserved for the frame offset is __________.
Q9➡| NET June 2021 Comprehension: Q5 to Q9 Read the following and answer the questions: Consider a machine with 16 GB main memory and 32-bits virtual address space, with page size as 4KB. Frame size and page size is same for the given machine. Find number of pages required for the given virtual address space?
Q10➡| UGC NET November 2020 Suppose you have a Linux file system where the block size is 2K bytes, a disk address is 32 bits, and i-node contains the disk addresses of the first 12 direct blocks of file, a single indirect block, and a double indirect block. Approximately, what is the largest file that can be represented by an i-node?
Q11➡| UGC NET November 2020 Which of the following cloud concept/s is/are related to pooling and sharing of resources? A) Virtual Memory B) Service C) Virtualization Choose the correct answer from the options given below:
Q12➡| UGC NET November 2020 Assuming that the system call fork () never fails, consider the following C programs P1 and P2 executed on a UNIX/ Linux system: Statement I: P1 displays “Happy” 8 times. Statement II: P2 displays “Happy” 12 times. In the light of the above statements, choose the correct answer from the options given below:
i ➥ Both Statement I and Statement II are true
ii ➥ Both Statement I and Statement II are false
iii ➥ Statement I is correct but Statement II is false
iv ➥ Statement I is incorrect but Statement II is true
Show Answer With Best Explanation
Answer: III Explanation: Fork is the primary method of process creation on Unix-like operating systems. Fork system call is used for creating a new process, which is called child process, which runs concurrently with the process that makes the fork() call (parent process).When fork() is called, parent & child process is run concurrently & complete program is executed for both parent process & child process. For P1:
Q13➡| UGC NET November 2020 Consider a hypothetical machine with 3 pages of physical memory, 5 pages of virtual memory, and < A,B,C,D,A,B,E,A,B,C,D,E,B,A,B> as the stream of page reference by an application. if P and Q are the number of page faults that the application would incur with FIFO and LRU page replacement algorithms respectively, then (P,Q)=_________(Assuming enough space for storing 3 page frames)
Q14➡| UGC NET November 2020 Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6 and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to adjacent one and Shortest Seek Time First (SSTF) algorithm is used?
Q15➡|UGC NET November 2020 Which of the following statements with respect to the multiprocessor system are true? A) Multiprocessor system is controlled by one operating system. B) In a Multiprocessor system, multiple computers are connected by means of communication lines. C) Multiprocessor system is classified as multiple instruction streams and multiple data stream systems.
Choose the correct answer from the options given below
i➥ (A) only
ii ➥ (A) and (B) Only
iii ➥(A) and (C) only
iv ➥ (B) and (C) only
Show Answer With Best Explanation
Answer: III Explanation:
Multiprocessor System: a multiprocessor is a computer system having two or more processing units (multiple processors) each sharing main memory and peripherals, in order to simultaneously process programs. (A) True : Multiprocessor system is controlled by one operating system. (B) False: In a Multiprocessor system, single computer (or Operating system) have multiple processor. (C) True: Multiprocessor system is classified as multiple instruction streams and multiple data stream systems.
Q17➡| UGC NET December 2019 Suppose a system has 12 magnetic tape drives and at time t0, three processes are allotted tape drives out of their need as given below: At time t0, the system is in safe state. Which of the following is safe sequence so that deadlock is avoided?
Q18➡| UGC NET December 2019 Identify the circumstances under which preemptive CPU scheduling is used : (a) A process switches from Running state to Ready state (b) A process switches from Waiting state to Ready state (c) A process completes its execution (d) A process switches from Ready to Waiting state Choose the correct option:
Q20➡| UGC NET December 2019 A counting semaphore is initialized to 8. 3 wait() operations and 4 signal() operations are applied. Find the current value of semaphore variable
Q21➡| UGC NET December 2019 Consider the following statements : (a) Windows Azure is a cloud-based operating system. (b) Google App Engine is an integrated set of online services for consumers to communicate and share with others. (c) Amazon Cloud Front is a web service for content delivery. Which of the statements is (are) correct?
Q24➡| UGC NET June 2019 A computer has six tapes drives with n processes competing for them. Each process may need two drives. What is the maximum value of n for the system to be deadlock free?
Q26➡| UGC NET June 2019 Consider a disk system with 100 cylinders. The requests to access the cylinders occur in the following sequence: 4,34,10,7,19,73,2,15,6,20 Assuming that the head is current at cylinder 50, what is the time taken to satisfy all requests if it takes 1ms to move from the cylinder to adjacent one and the shortest seek time first policy is used?
Q27➡| UGC NET June 2019 At a particular time of computation, the value of a counting semaphore is 7. Then 20 P(wait) operations and 15 V(signal) operations are completed on this semaphore. What is the resulting value of the semaphore?
Q28➡| UGC NET June 2019 Consider three intensive processes, which requires 10,20 and 30 units of time and arrive at times 0,2 and 6 respectively. how many context switches are needed if the operating system implements a shortest remaining time first scheduling algorithm? Do not count the context switches at time zero ad at the end
Q29➡| UGC NET June 2019 Consider that a process has been allocated 3 frames and has a sequence of page referencing 1,2,1,3,7,4,5,6,3,1 What shall be the difference i page faults for the above string using the algorithm of LRU and Optimal page replacement for referencing the string?
Q31➡| UGC NET June 2019 A processor can support a maximum memory of 4 GB where memory is word addressable and a word is 2 bytes. What will be the size of the address bus of the processor?
Q32➡| UGC NET June 2019 Which of the following UNIX/Linux pipes will count the number of lines in all the files having .c and .h as their extension in the current working directory?
Q33➡| UGC NET June 2019 Which of the following are not shared by the threads of the same process? (a) Stack (b) Registers (c) Address Space (d) Message Queue
Q34➡| UGC NET December 2018 Suppose a system has 12 instances of some resources with n processes competing for that resource. Each process may require 4 instances of the resource. The maximum value of n for which the system never enters into deadlock is
Q35➡| UGC NET December 2018 Suppose P,Q and R are co-operating processes satisfying Mutual Exclusion condition. Then if the process Q is executing in its critical section then
i ➥ ‘P’ executes in critical section
ii ➥ ‘R’ executes in critical section
iii ➥ Neither ‘P’ nor ‘R’ executes in their critical section
iv ➥ Both ‘P’ and ‘R’ executes in critical section
Q36➡| UGC NET December 2018 A Computer uses a memory unit with 256K word of 32 bits each. A binary instruction code is stored in one word of memory. The instruction has four parts: an indirect bit, an operation code and a register code part to specify one of 64 registers and an address part. How many bits are there in operation code, the register code part and the address part?
Q37➡| UGC NET December 2018 Consider the following set of processes and the length of CPU burst time given in milliseconds: Assume that processes being scheduled with Round-Robin Scheduling Algorithm with Time Quantum 4ms. Then The waiting time for P4 is_______ms.
Q38➡| UGC NET December 2018 Consider a system with 2 level cache. Access times of Level 1, Level 2 cache and main memory are 0.5 ns, 5 ns and 100 ns respectively. The hit rates of Level1 and Level2 caches are 0.7 and 0.8 respectively. What is the average access time of the system ignoring the search time within cache?
Q39➡| UGC NET December 2018 Consider a disk pack with 32 surfaces, 64 tracks and 512 sectors per pack. 256 bytes of data are stored in a bit serial manner in a sector. The number of bits required to specify a particular sector in the disk is
Q42➡| UGC NET December 2018 Suppose for a process P, reference to pages in order are 1, 2, 4, 5,2,1,2,4. Assume that main memory can accommodate 3 pages and the main memory has already pages 1 and 2 in the order 1 – first, 2- second. At this moment, assume FIFO Page Replacement Algorithm is used then the number of page faults that occur to complete the execution of process P is
Q45➡| UGC NET June 2018 At a particular time of computation, the value of a counting semaphore is 10. Then 12 P operations and “x” V operations were performed on this semaphore. If the final value of semaphore is 7, x will be :
Q46➡| UGC NET June 2018 In a paged memory, the page hit ratio is 0.40. The time required to access a page in secondary memory is equal to 120 ns. The time required to access a page in primary memory is 15 ns. The average time required to access a page is
Q47➡| UGC NET June 2018 In a multi-user operating system, 30 requests are made to use a particular resource per hour, on an average. The probability that no requests are made in 40 minutes, when arrival pattern is a poisson distribution, is __
Q48➡| UGC NET June 2018 Normally user programs are prevented from handling I/O directly by I/O instructions in them. For CPUs having explicit I/O instructions, such I/O protection is ensured by having the I/O instructions privileged. In a CPU with memory mapped I/O, there is no explicit I/O instruction. Which one of the following is true for a CPU with memory mapped I/O ?
i ➥ I/O protection is ensured by operating system routines.
ii ➥ I/O protection is ensured by a hardware trap.
iii ➥ I/O protection is ensured during system configuration.
Q50➡| UGC NET June 2018 Which of the following statements are true ? (i) External Fragmentation exists when there is enough total memory space to satisfy a request but the available space is contiguous. (ii) Memory Fragmentation can be internal as well as external. (iii) One solution to external Fragmentation is compaction. Code:
Q52➡| UGC NET June 2018 Consider a virtual page reference string 1, 2, 3, 2, 4, 2, 5, 2, 3, 4. Suppose LRU page replacement algorithm is implemented with 3 page frames in main memory. Then the number of page faults are .
Q53➡| UGC NET June 2018 Consider the following three processes with the arrival time and CPU burst time given in milliseconds : The Gantt Chart for preemptive SJF scheduling algorithm is
