COSC 4330                   MIDTERM                           10/20/98

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)  All interprocess communication in UNIX are done through pipes.
               
     (b)  VMS uses a variant of the Round-Robin policy.

     (c)  Making all remote procedures idempotent greatly simplifies the
          task of the RPC server.

     (d)  In a symmetric multiprocessor organization, there can be several
          copies of the kernel running at the same time.

     (e)  Windows NT uses a monolithic kernel.    
        
     (f)  In BSD UNIX, the priority of a process is function of its past
         CPU usage.

2.   Answer  in one sentence or less to each of the following questions
     (4×5 points)
     
     (a)  What does a server do when it is not processing client requests?
               
     (b)  What is the major disadvantage of non-preemptive scheduling
          policies?
     
      (c)  What is the major disadvantage of user-level threads? 

      (d)  What is the major advantage of indirect communication primitives?

3.   How  would  you  pass a  linked list to a remote  procedure?  (10
     points)

4.   What are the two events that can force a running process to return to
     the ready queue ? (2×5 points)

5.   How  would you implement the at most once semantics in  a  remote
     procedure call package? (10 points)?

6.   Consider the following system V scheduler:
 
     #ts_quantum ts_tqexp ts_slpret ts_maxwait ts_lwait LEVEL
          800       XXX       1        4000        1   #  0
          400        0        2        2000        2   #  1
          200        1        3        1000       YYY  #  2
          100        3       ZZZ        500        3   #  3
     
     (a)  How many priority levels does it have?    ________ levels
          (5 points)
          
     (b)  What are the sole reasonable values for the three missing entries
          (3×5 points)?
     
          XXX   =______           YYY=  ______               ZZZ=_____
         

--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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