UNIVERSITY OF HOUSTON Department of Computer Science COSC 6360-Operating Systems MIDTERM November 5, 1990 Be concise but complete. 1. Explain the function and the purpose of the set user-ID bit in UNIX. (10 points) 2. What makes the choice of an optimal block size so compli- cated in UNIX. (4 points) How is Berkeley UNIX solving the problem? (6 points) 3. What is the difference between stream sockets and datagram sockets in Berkeley UNIX? (10 points). 4. Describe and compare the page replacement policies of VMS and Mach. (20 points) 5. Explain how Berkeley UNIX implements the page-referenced bit (7 points) and give the major limitation of that approach (3 points) 6. Which steps are taken by the MULTICS supervisor when it activates a segment? (10 points) THIS QUESTION WAS RELATED TO A PAPER THAT IS NOT ANYMORE IN THE READING LIST. 7. What is the purpose of the MULTICS linkage segment? (4 points) Could this information have been stored in the pro- cedure segment? (6 points) THIS QUESTION WAS RELATED TO A PAPER THAT IS NOT ANYMORE IN THE READING LIST. 8. Contrast the advantages and disadvantages of shared-memory vs. message-based IPC? (14 points) What steps can be taken to improve the applicability-or the performance-of either of them? (6 points)