TRIBHUVAN UNIVERSITY
INSTITUTE OF SCIENCE AND TECHNOLOGY
2082 B.S.
Candidates are required to give their answers in their own words as far as practicable.
Group A
Long Answer QuestionsAttempt any Two questions.
- 1Explain the differences between deadlock, livelock and starvation. A system has four processes and five allocated resources. Given the following current allocation and maximum needs, find the smallest value of x for which this is a safe state.
- 2How are files implemented using linked list allocation? How many disk operations are needed to fetch the i-node for a file with the path name /usr/ast/courses/os/handout.t? Assume that the i-node for the root directory is in memory, but nothing else along the path is in memory. Also assume that all directories fit in one disk block.
- 3If a disk has double interleaving, does it also need cylinder skew in order to avoid missing data when making a track-to-track seek? Justify your answer. Consider a disk queue with requests for I/O to blocks on cylinders 24, 90, 133, 43, 188. The head is initially at cylinder number 100 and the cylinders are numbered from 0 to 199. Calculate the total head movement for servicing the request using FCFS, SSTF and CSCAN.
Group B
Short Answer QuestionsAttempt any Eight questions.
- 4List and describe two main functions of an operating system.
- 5Define segmentation. Why do we need multiple queues in process scheduling?
- 6What do you mean by open source operating systems? Why do you think the designers of Linux made it impossible for a process to send a signal to another process that is not in its process group?
- 7During implementing mutual exclusion, how can you solve the problem of busy wait? Explain.
- 8What is race condition? Explain how time quantum value and context switching time affect each other in a round-robin scheduling algorithm.
- 9Five batch jobs A, B, C, D and E, with estimated running times 10, 6, 2, 4 and 8 minutes respectively, arrived at the same time. Determine the average turnaround time for the scheduling algorithms FCFS and SJF.
- 10Given the page reference string: 1, 2, 3, 4, 2, 1, 5, 6, 2, 1, 2, 3, 7, 6, 3, 2, 1, 2, 3, 6, compute the number of page faults for FIFO page replacement algorithm.
- 11What is Belady's anomaly? For the decimal virtual addresses 20000, 32768, 60000, compute the virtual page number and offset for a 4-KB page and for an 8-KB page.
- 12Differentiate between: a) Preemptive and non-preemptive scheduling. b) Physical address and logical address.