Question No.3: Numerical [12 Marks]

1. Consider the free memory layout shown below (the blocks are ordered from top to bottom). Draw to the what the free memory layouts would be after satisfying requests for (in order) memory blocks of size 187KB, 329KB, 486KB, 407KB and 285KB.

445K

250K

395K

600K

290K

325K

355K

1. Draw one memory layout for the Best-fit and Worst-fit.
2. Which algorithm makes the efficient use of the memory? Why
3. Is there any kind of fragmentation?

2. Given the following stream of page references by an application, calculate the number of page faults the application would incur with the following page replacement algorithms. Assume that all pages are initially free.

Reference Stream: D A B F A E A E F D A B C A C F B A F D A B F A E

Pages = 4

1. LRU page replacement.
2. OPT page replacement.