CMSC 714 Midterm (similar to prior 714 exams, but more questions)

(1)  This exam is closed book, closed notes, and closed neighbor.

(2) You have 75 minutes to complete this exam.  If you finish early, you
    may turn in your exam at the front of the room and leave.  However if
    you finish during the last ten minutes of the exam please remain seated
    until the end of the exam so you don't disturb others.
	
(3) Partial credit will be given for most questions assuming I can figure
    out what you were trying to do.
	
(4) Please write neatly. Print your answers if your handwriting is hard to
    read. If you write something, and wish to cross it out, simply put an X
    through it.

1.	Define and explain the following terms:
A.	Vector Processor
B.	Causal Ordering
C.	Reduction Operation
D.	Space Sharing

2.	Several of the parallel computers we looked at this
        semester provided globally shared memory but lacked cache
        coherence.
A.	Name one of those systems.
B.	What are the implications of having such an architecture on the
	programmer and programming model (for example which of the models
	we looked at would be well suited for this type of machine)?

3.	The Valgrind and Dyninst systems each are designed to
        modify compiled programs.  Compare and contrast how the tools work and
	their various features.

4.	Some proponents of shared memory programming models claim the major
	advantage of shared memory over message passing is that don't have
	to worry about where your data is located since all memory is
	shared. Explain why this assumption is naive if performance matters.

5.	Some data race detection systems, such as Eraser, use a lockset
	algorithm to find synchronization problems.
A.	Will the system find all races in a program (explain your answer)?
B.	Describe two examples of cases where a program can be free
	of data races but still violate the locking discipline checked by
	such systems.