Department of Computer Science COSC 6360--Operating Systems MIDTERM EXAMINATION March 5, 1996 This exam is closed book. You can have two sheets (i.e., four pages) of notes. 1. What is a superblock? (4 points) What does Berkeley UNIX to protect superblocks against disk failures and why? (6 points) 2. What made the UNIX toolkit approach so successful at the beginning? (5 points) Which problems does it encounter now that we are in the age of graphical and WYSIWYG applications?(5 points) (Hint: Think about applications of pipes.) 3. Describe the VMS page replacement policy (10 points) and explain which of its features made it particularly ill-suited for UNIX ( 5 points) 4. In Satyanarayanan’s Lightweight Recoverable Virtual Memory, what is ano_flush transaction? (4 points) What are their major advantage ( 3 points) and disadvantage (3 points) 5. What is inheritance in Mach? (5 points) At which level is it defined? (5 points) Explain how Mach uses it to support both regular and lightweight processes. (10 points)(Hint: Do not forget mapped files.) 6. According to Talluri et al. what is the difference between superpages and subblocks? (5 points) 7. Which events trigger upcalls in scheduler activations? (10 points) 8. In Birrell and Nelson’s implementation of remote procedure calls, what is happening when the calling process does not receive promptly a result message? (5 points) What will happen later if the result message continues to be delayed? (5 points) 9. What is the main purpose of a shuttle in the Spring Kernel? (10 points) 10. UNIVERSITY OF HOUSTON Department of Computer Science COSC 6360--Operating Systems MIDTERM EXAMINATION March 5, 1996 This exam is closed book. You can have two sheets (i.e., four pages) of notes. 1. What made the UNIX toolkit approach so successful at the beginning? (5 points) Which problems does it encounter now that we are in the age of graphical and WYSIWYG applications?(5 points) (Hint: Think about applications of pipes.) 2. What is a superblock? (4 points) What does Berkeley UNIX to protect superblocks against disk failures and why? (6 points) 3. What is a no_flush transaction in Satyanarayanan’s Lightweight Recoverable Virtual Memory,? (4 points) What are their major advantage ( 3 points) and disadvantage (3 points) 4. Describe the VMS page replacement policy (10 points) and explain which of its features made it particularly ill-suited for UNIX ( 5 points) 5. What is inheritance in Mach? (5 points) At which level is it defined? (5 points) Explain how Mach uses it to support both regular and lightweight processes. (10 points)(Hint: Do not forget mapped files.) 6. Which events trigger upcalls in scheduler activations? (10 points) 7. According to Talluri et al. what is the difference between superpages and subblocks? (5 points) 8. What is the main purpose of a shuttle in the Spring Kernel? (10 points) 9. In Birrell and Nelson’s implementation of remote procedure calls, what is happening when the calling process does not receive promptly a result message? (5 points) What will happen later if the result message continues to be delayed? (5 points)