CMSC 714 Midterm (Fall 2008)


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


(2)     You have 70 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)     Write all answers in the supplied exam booklet. Start each new problem (but not sub-problem) on a new page.


(4)     Partial credit will be given for most questions assuming I can figure out what you were doing.


(5)     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. (25 points) Define and explain the following terms:

A. Data Parallelism

B. Space Sharing vs. Time Sharing

C. Multi-Grid

D. Owner Computes

2. (20 points)  Scheduling

A. Explain why co-scheduling is important, and how it can be obtained explicitly or implicitly.

B. What is symbiotic space sharing and how can it improve system performance?

3. (20 points)  Compare and contrast fat tree and 3-d torus networks in their ability to handle different types of message passing operations including: nearest neighbor, reduction, and all-to-all communication.

4.(20 points)  Explain three issues that must be overcome when programming the Cell processor that are not present (or as significant) on a cluster of commodity workstations using MPI.

5.(15 points)  Explain how Terra’s MTA is able to achieve good performance without caches.