8 Questions - Midterm Examination Fall 2000 | CPSC 614, Exams of Computer Science

Download 8 Questions - Midterm Examination Fall 2000 | CPSC 614 and more Exams Computer Science in PDF only on Docsity! Midterm Exam CPSC 614 Spring 2000 Name________________________________________________ Student ID____________________________________________ This exam is 50 minutes, closed book. Show your work for partial credit. 1. Assume that we make an enhancement to a computer that improves some mode of execution (e.g. floating- point instructions) by a factor of 10. Enhanced mode (e.g. floating-point) is used 50% of the time, measured as a percentage of the execution time when the enhanced mode is in use. Recall that Amdahl's Law depends on the fraction of the original, unenhanced execution time that could make use of enhanced mode. Thus, we cannot directly use this 50% measurement to compute speedup with Amdahl's Law. a. (10pts) What is the speedup we have obtained from enhanced mode? b. (5pts) What percentage of the original execution time has been converted to enhanced mode? 2. (10pts) Identify all the data hazards in the following code fragment, along with the type of each hazard identified. You can mark them appropriately on the code fragment and use acronyms to specify the hazard type. ADD R1, R2, R3 SUB R4, R1, R5 AND R2, R4, R7 XOR R10, R2, R11 OR R2, R12, R13 3. (15pts) What are the dependencies between S1 and S2 in the loop below? Is this loop parallel (i.e. can the loop iterations be executed in parallel)? If not, show how to make it parallel. for (I = 1; I <=100; I++) { A[I] = A[I] + B[I]; /* S1 */ B[I+1] = C[I] + D[I]; /* S2 */ }