UNIVERSITY OF HOUSTON Department of Computer Science COSC 6360--Operating Systems MIDTERM EXAMINATION March 28, 1994 This exam is closed book. You can have two sheets (i.e. four pages) of notes. 1. Describe the major differences between the ways MULTICS segments and UNIX files are stored on disk. You don't have to discuss UNIX special files nor UNIX access control lists. (20 points) THIS QUESTION WAS RELATED TO A PAPER THAT IS NOT ANYMORE IN THE READING LIST. IT WILL BE NOT BE ASKED AGAIN. 2. 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. IT WILL BE NOT BE ASKED AGAIN. 3. What makes a fork() system call so costly? (5 points) Which steps are taken by (a) Berkeley UNIX (5 points) and (b) MACH (5 points) to make forks less costly? 4. Which considerations motivated the introduction of a guarded command in Hoare's CSP language? (10 points) 5. What are the major issues in the passing of parameters in Remote Procedure Calls (20 points) 6. What did Birrell and Nelson do to reduce process creation costs in their remote procedure call package? (5 points) What would have been an even better solution? (5 points) 7. According to Bershad et al., what is an upcall ? (5 points) 8. Describe the exchange of messages between a client workstation and the Kerberos server at login and explain the contents of each message. (10 points)