Operating Systems - May 2012

Computer Engineering (Semester 5)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks. 1(a) What are the main advantages for an operating system designer of using virtual machine architecture? What are the main advantages for a user. (10 marks) 1(b) Consider the following snapshot of the system:

Answer the following using banker's algorithm:
i) Determine the total amount of resource of each type
ii) What is the content of need matrix
iii) Determine if the system is in safe state using safety algorithm
iv) If a request from process p1 arrives for (0,4,2,0) can the request be granted immediately?(10 marks) 2(a) On a disk with 1,000 cylinders, numbered 0 to 999, compute the number of tracks the disk arm must move to satisfy all the requests in the disk queue. Assume that the last request serviced was at track 345 and head is moving towards track 0,. The queue in FIFO order contains requests for the following tracks: 123, 874, 692, 475, 105, 376. Perform the computation for following disk scheduling algorithms: i) FIFO ii)SSTF iii)SCAN(10 marks) 2(b) What is RTOS? Give the classification of RTOS and comparison of any two RTOS.(10 marks) 3(a) Consider the following snapshot of the process to be executed. Draw the gantt chart and determine the average waiting time and average turnover time for FCFS, SJF (pre-emptive), SJF (non- pre-emptive) and round robin(quantum=2) scheduling algorithms.
(10 marks) 3(b) Describe Inode and FAT structure. (10 marks) 4(a) On a simple paging system with 224 bytes of physical memory 256 pages of logical address space and page size of 210 bytes.i) Determine the no. of bits in physical address that specify the page frameii)How many entries are present in the page table?iii) How many bits are in logical address space?(10 marks) 4(b) Suggest an implementation of binary semaphores that avoids busy waiting.(10 marks) 5(a) What is kernel? Describe briefly the approaches of designing kernel(10 marks) 5(b) Consider the following page traces in a demand paging system with 3 page frames. 2, 3, 1, 1, 2, 3, 4, 6, 2, 3, 4, 3, 1, 2, 3.Determine the number of page faults and hit ratio using FIFO and LRU page replacement algorithms. (10 marks) 6(a) Describe programmed I/O and DMA(10 marks) 6(b) Consider a disk having 8 surfaces. Each surfaces having an outer diameter of 16cm and inner of 6cm and inner track space is 0.2mm. There are 32 sectors in each track. If disk address for reading a byte or sector on any surface track of disk is 27 bits. What is sector size in bytes if disk rotates at 3600rpm.What is effective data transfer rates in bytes/sec? (10 marks)

Write short notes on the following:-

7(a) Monitor(5 marks) 7(b) Distributed O.S. (5 marks) 7(c ) Network O.S. (5 marks) 7(d) Symbian O.S. (5 marks)