CS162, Spring/1992
Midterm #2
Professor Thomas Anderson
General Information:
This is a closed book examination. You have 60 minutes to answer as many question as possible. The
number in parentheses at the beginning of each question indicates the number of points given to the question;
there are 60 points in all. Write all of your answers directly on this paper. Make your anwers as concise as
possible (you needn't cover every available nano-acre with writing).
Problem #1 (6 points)
For each of the following statements, indicate in one sentence whether the statement is true or false, and why.
(a) Binary semaphores are those that are used by no more than two threads.
Answer: False, binary semahpores contain two states 0 or 1.
(b) The Banker's algorithm is a way of preventing deadlock
Answer: True, no process is allowed into a section if deadlock is possible.
(c) A multi-level indexed file permits faster random access than a contiguously allocated file.
Answer: False, contiguous files may be easily jumped through, while the multi-level file must seek right
blocks.
Problem #2 (8 points)
For each of the following items, write a sentence definition:
(a) Atomic
Answer: An atomic function or command cannot be interrupted in between.
(b) Deadlock
Answer: A state where all threads are waiting for a resource held by another and nothing can therefore finish.
(c) Disk cylinder
Answer: The same track on all platters in a disk pack.
(d) Doubly indirect block
Answer: A block of pointers to blocks of pointers which in turn point to file blocks.
CS162, Midterm #2, Spring/1992
CS162, Spring/1992 Midterm #2 Professor Thomas Anderson 1
