UNIVERSITY OF HOUSTON Department of Computer Science COSC 6360--Operating Systems MIDTERM EXAMINATION March 8, 1996 This exam is closed book. You can have two sheets (i.e., four pages) of notes. 1. What are clustered page tables? (5 points) What is their major advantages over the traditional page table organizations? (2×5 points) How do they interact with the TLB miss handling software? (5 points) 2. What was the major reason for introducing symbolic links in Berkeley UNIX? (5 points) 3. Describe the organization of Mach's address map? (10 points) 4. What is the major purpose of Mach external pagers? (5 points) 5. What are the major functions of the two following MULTICS data structures: a) active segment table (5 points)? b) known segment table? (5 points) THIS QUESTION WAS RELATED TO A PAPER THAT IS NOT ANYMORE IN THE READING LIST. IT WILL BE NOT BE ASKED AGAIN. 6. What did Babaoglu and Joy do to overcome the lack of a page referenced bit on the VAX? (5 points) What was then the major drawback of their approach? (5 points) Is this issue still important today? (5 points) 7. How does MULTICS implement intersegment linking? (5 points) What was the special problem raised by the linking of procedure segments? (5 points) THIS QUESTION WAS RELATED TO A PAPER THAT IS NOT ANYMORE IN THE READING LIST. IT WILL BE NOT BE ASKED AGAIN. 8. According to Satyanarayanan et al., what was the main reason for insulating the recoverable virtual memory from the virtual memory subsystem? (5 points) What price did they have to pay for this decision? (5 points) 9. According to Anderson et al., what are the two significant inherent costs to managing threads in the kernel? (2×5 points) 10. What are the purpose of the alternative command in CSP? (5 points)?