Question 1)a) Describe hashed page tables. Is the table size larger or smaller than inverted page table?
b) Consider a paging system with page table stored in memory
i) If memory reference takes 200 nanoseconds, how long does a paged memory reference take
ii) If we add associative registers, 75% of all page table references are found in the associative registers what is the effective memory reference time?
c) Write down the differences between user-level and kernel-level threads?
Under what situation is one type better than the other?
Question 2)a) Explain the cause of thrashing? How does the system detect thrashing? Once it detects thrashing, what can the system do to eradicate this problem?
b) Consider the following page reference string:
1, 2, 3, 4, 2, 1, 5, 6, 2, 1, 2, 3, 7, 6, 3, 2, 1, 2, 3, 6.
How many page faults would occur for the LRU replacement algorithms, assuming there are 3 page frames?
c) Suppose that a disk drive has 5000 cylinders, numbered 0 to 4999. The drive is currently serving a request at cylinder 143, and the previous request was at cylinder 125. The queue of pending requests, in FIFO order, is 86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130 Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests, for SSTF disk-scheduling algorithms?
Question 3)a) Why are monitors used? Illustrate how you obtain deadlock free solution to the dining-philosopher’s problem using monitors.
b) Show that if the wait() and signal() semaphore operations are not executed atomically, then mutual exclusion may be violated.
c) Write detail note on the stack and buffer overflow way of attacking a network
Question 4)a) Compare the different techniques for implementing the access matrix
b) Describe acyclic graph directories.
c) How is physical memory managed in the case of Linux systems?