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Operating Systems MCQs

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1. Supervisor call :-




2. Round-robin scheduling is essentially the preemptive version of :-




3. FIFO scheduling is :-




4. In real time operating system,which of the following is the most suitable scheduling algorithms




5. In round-robin CPU scheduling, as the time quantum is increased , the average turn around time




6. Preemptive scheduling is the strategy of temporarily suspending a running process




7. Which of the following statements is true? 1. Shortest remaining time first scheduling may cause starvation 2.Preemptive scheduling may cause starvation 3. Round robin is better than FCFS in terms




8. Function of operating system :-




9. In which state, a process goes to the CPU




10. If a process require a input/output then process goes to




11. Which of the following statements are true?




12. At particular time, the value of a counting semaphore is 10. It will become 7 after




13. At particular time, the value of a counting semaphore is 4. It will become 7 after




14. At particular time, the value of a counting semaphore is 10. It will become 9 after




15. At particular time of computation the value of a counting semaphore in 7. Then 20P operation and X V operation were performed on this semaphore. If the final value of semaphore is 5, X will be -




16. Value of Counting semaphore is -




17. A critical region




18. A thread -




19. which one is a high level abstraction over semaphore ?




20. A binary semaphore




21. A threads is a




22. Consider The following statements with respect to user clever threads and kernel supported threads: a. context switch is faster with kernel supported threads b. for user level threads, a system call




23. Necessary condition for deadlock




24. Method of handling deadlock ?




25. Banker algorithms is a example of




26. Mutual exclusion is a problem occurs between




27. A system has 3 processes sharing 4 resources. If a each process need maximum of 2 units, then




28. With a single resource, deadlock occurs




29. Processes wait for infinite time in




30. A state is safe if the system call allocate resources to each process(upto its maximum) in same order and still avoid deadlock. Then




31. Resources are allocated to a process on non-shareable basic in




32. The method of dealing with deadlock problem is




33. Which of the following is NOT a valid deadlock prevention scheme?




34. Consider a virtual memory system with FIFO page replacement policy. For an arbitrary page access pattern, increasing the number of page frames in main memory will




35. Which of the following requires a device driver?




36. Consider three CPU-intensive processes, which require 10, 20 and 30 time units and arrive at times 0, 2 and 6, respectively. How many context switches are needed if the operating system implements a s




37. A CPU generates 32-bit virtual addresses. The page size is 4 KB. The processor has a translation look-aside buffer (TLB) which can hold a total of 128 page table entries and is 4-way set associative.




38. In which one of the following page replacement policies, Belady’s anomaly may occur?




39. The essential content(s) in each entry of a page table is / are




40. Consider a disk system with 100 cylinders. The requests to access the cylinders occur in following sequence: 4, 34, 10, 7, 19, 73, 2, 15, 6, 20 Assuming that the head is currently at cylinder 50, wh




41. A process executes the code fork(); fork(); fork(); The total number of child processes created is




42. Total number of child processes created by following program is for(i=0;i<3;i++) fork();




43. Total number of child processes created by following program is for(i=0;i<4;i++) fork();




44. Total number of child processes created by following program is for(i=0;i<1;i++) fork();




45. Total number of child processes created by following program is x for(i=0;i<8;i++) fork(); then x-250= ?




46. A file system with 300 GByte uses a file descriptor with 8 direct block address. 1 indirect block address and 1 doubly indirect block address. The size of each disk block is 128 Bytes and the size of




47. A multilevel page table is preferred in comparison to a single level page table for translating virtual address to physical address because




48. Consider a machine with 64 MB physical memory and a 32-bit virtual address space. If the page size is 4KB, what is the approximate size of the page table?




49. A system uses FIFO policy for page replacement. It has 4 page frames with no pages loaded to begin with. The system first accesses 100 distinct pages in some order and then accesses the same 100 pages




50. Memory protection is of no use in




51. In which of the following page replacement policies Belady anomaly may occur ?




52. A page fault occurs




53. Virtual memory is commonly implemented by -




54. The mechanism that bring a page into memory only when it is needed is called-




55. Which of the following statement is false?




56. The first fit best fit and worst fit algorithm can be used for-




57. The essential contents in each entry of a page table is -




58. A file is




59. The simplest directly structure is -




60. Disadvantage of single level directory is -




61. Solution of name collision problem is




62. which structure prohibits sharing of file and directory




63. There are no cycle in which of the directory -




64. The lowest level of I/O control consists of -




65. Access time is the highest in case of




66. What is the shell ?




67. If the disk head located initially at 32, find the no of disk moves required with FCFS if the disk queue of I/O block requests are 98,37,14,124,65,67




68. Magnetic tape can serve as




69. Supervisor state is




70. The operating systems manages




71. PCB is stands for -




72. Which of the following file name extension suggests that the file is backup copy of another file ?




73. Which is not the state of the process ?




74. Which is the state of process ?




75. The problem of thrashing is effected by scientifically by-




76. The number of processes completed per unit time is known as




77. What is the memory from 1k to 640k called ?




78. Process state is a part of




79. A program at time of execution is called ?




80. A thread is a ?




81. The state of process after it encounters an I/O instruction is




82. The major problem with priority scheduling is ?




83. ______ OS pays more attention on the meeting of the the time limit




84. A process said to be in ______ state if it was waiting for an event that will never occur




85. The operating system of a computer serve as a software between the user and the




86. The removal of process from active contention of CPU and reintroduce them into memory later is known as




87. _______ allocates the largest hole available in the memory




88. A binary semaphore -




89. The hardware mechanism that enable a device to notify the CPU is called




90. The banker algorithms is used




91. Which data structure are used for process scheduling ?




92. _______ is a high level abstraction over semaphore




93. How many page faults occur for optimal page replacement following reference string, with four page frames ? 1,2,3,4,5,3,4,1,6,7,8,7,8,9,7,8,9,5,4,5,4,2




94. If you dont know which version of MS-DOS you are working with, which command will you use after booting your operating system ?




95. How many page faults occur in LRU replacement following reference string, with four page frames ? 7,0,1,2,0,3,0,4,2,3,0,3,2,1,2,0,1




96. Which scheduling policy is most suitable for a time sharing operating systems ?




97. A processor needs software interrupts to




98. Which of the following does not interrupt a running process




99. System calla are usually invoked by using