COSC 4330                          MIDTERM                         3/4/99

Closed Book.   You can have one sheet of notes.

1.   For  each  of  the  statements below, indicate  in  one  sentence
     whether the statement is true or false (2 points), and why (3 points).
     
     (a)  It makes no sense to have memory protection on a single user
          system.
   
     (b)  A process waiting on a semaphore is in the suspended state.

     (c)  Shortest Job First always provides the absolute minimum waiting
          time for very short CPU requests.

     (d)  Processes often interrupt themselves.

2.   Explain why some applications are better implemented with virtual
     circuits and others with datagrams.  Give at least one example of
     both. (10 points)
  
3.   Answer   in  one  sentence  or less  to  each  of  the  following
     questions (4×5 points)
     
     (a)  Under which conditions can a running process return to the
          ready state?

      (b)  What is the major advantage of microkernels?

      (c)  What is the major advantage of non-blocking sends?

     (d)  What is the major benefit of adding more RAM to a computer?

4.   Explain  why  it is easier to write a multithreaded  file  server
     using kernel-level threads than user-level threads? (10 points)

5.   What would be the consequences of much faster context switches on
     (a) kernel organizations, (b) lightweight process support and (c)
     scheduling policies?  (3×5 points)

6.   How  many  lines  will  be printed by the following  program?  (5
     points)
          main()  {
               fork();
               printf("One!\n");
               fork();
               printf("Two!\n");
          }
                                   It will print exactly ____ lines.


7.   Consider the following system V scheduler:

          #ts_quantum ts_tqexp ts_slpret ts_maxwait ts_lwait LEVEL
               800        0        1        4000        1   #  0
               400        0        2        2000        2   #  1
               200        1        3        1000        1   #  2
               100        2        4         500        3   #  3
     
     What  are  the  two incorrect parameters?  What  would  be  their
     correct values?  (4×5 points)
     
     On level ____ parameter ______________ should be set to _______

     On level ____ parameter ______________ should be set to _______
--IMPORTANT----IMPORTANT----IMPORTANT----IMPORTANT----IMPORTANT--
Please do not try to answer these questions by yourself BEFORE
having a clear idea of what's on the test for which you are
studying.

Materials covered in each test DO VARY from semester to semester
because the pace of the course can change, some materials are be
added and other deleted almost every semester.
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