Review Problems for CS 30200 / ECE 46810 Exam 2
                             Spring 2021


Version 1.0.  (In case I need to modify something.)


The exam is over Chapters 13, 15, 16.1, 18.1-18.3, 21, and 22 from the textbook.
http://pages.cs.wisc.edu/~remzi/OSTEP/
http://pages.cs.wisc.edu/~remzi/OSTEP/vm-intro.pdf
http://pages.cs.wisc.edu/~remzi/OSTEP/vm-mechanism.pdf
http://pages.cs.wisc.edu/~remzi/OSTEP/vm-segmentation.pdf
http://pages.cs.wisc.edu/~remzi/OSTEP/vm-paging.pdf
http://pages.cs.wisc.edu/~remzi/OSTEP/vm-beyondphys.pdf
http://pages.cs.wisc.edu/~remzi/OSTEP/vm-beyondphys-policy.pdf



16. This problem is about what can be done when a process is larger
than physical memory, that is, a process has more virtual pages than
there are physical page frames.

Assume that a process has four pages (numbered 0,1,2,3) in its virtual
address space but the computer has only three physical page frames
(numbered 0,1,2). The following tables show two possible sequences of
referenced virtual page numbers by the running process. Write down in
the empty slots below each page reference the virtual page that is
loaded into each of the physical page frames just after the page
reference (in other words, what does the process's page table look
like just after each page reference?). Also, write down the total
number of page hits and misses. Use the "Leased Recently Used" (LRU)
page replacement policy in both cases, so you replace the contents
of the page frame that was used the farthest back in time.

    Page Referenced:   0   1   2   3   0   1   2   3
       Page Frame 0:   0   0   0   3   3   3   2   2
       Page Frame 1:       1   1   1   0   0   0   3
       Page Frame 2:           2   2   2   1   1   1
             faults:   x   x   x   x   x   x   x   x

# of hits = 0
# of misses = 8


    Page Referenced:   0   1   0   1   2   3   2   3
       Page Frame 0:
       Page Frame 1:
       Page Frame 2:
             faults:

# of hits =
# of misses =




17. Suppose a computer has 4 physical pages frames, and a process 
references its virtual pages (page numbers 0 through 7) in the 
following order:

        0 2 1 3 5 4 6 3 7 4 7 3 3 5 5 3 1 1 1 7 2 3 4 1

   a) Suppose the kernel uses FIFO page replacement algorithm.  
        How many page faults would the process have?  
        Which page references are page faults?
   b) Suppose the kernel uses LRU as the page replacement algorithm.
        How many page faults would the process have?  
        Which page references are page faults?
   c) Suppose the kernel uses the optimal page replacement algorithm.
        How many page faults would the process have?  
        Which page references are page faults?


FIFO
Page Referenced:  0 2 1 3 5 4 6 3 7 4 7 3 3 5 5 3 1 1 1 7 2 3 4 1
   Page Frame 0:  0 0 0 0 5 5 5 5 5 5 5 3 3 3 3
   Page Frame 1:    2 2 2 2 4 4 4 4 4 4 4 4 5 5
   Page Frame 2:      1 1 1 1 6 6 6 6 6 6 6 6 6
   Page Frame 3:        3 3 3 3 3 7 7 7 7 7 7 7
         faults:  x x x x x x x   x     x   x


LRU
Page Referenced:  0 2 1 3 5 4 6 3 7 4 7 3 3 5 5 3 1 1 1 7 2 3 4 1
   Page Frame 0:
   Page Frame 1:
   Page Frame 2:
   Page Frame 3:
         faults:


Optimal
Page Referenced:  0 2 1 3 5 4 6 3 7 4 7 3 3 5 5 3 1 1 1 7 2 3 4 1
   Page Frame 0:  0 0 0 0 5 5 5 5 5 5 5 5 5 5 5 5 1 1 1 1 1 1 1 1
   Page Frame 1:    2 2 2 2 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4
   Page Frame 2:      1 1 1 1 6 6 7 7 7 7 7 7 7 7 7 7 7 7 2 2 2 2     
   Page Frame 3:        3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
         faults:  x x x x x x x   x               x       x