CIS5930midterm08 - HPC Midterm Exam Fall 2008(Please print Name Put the answers on these sheets Use additional sheets when necessary You can

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HPC Midterm Exam - Fall 2008 Name: (Please print) Put the answers on these sheets. Use additional sheets when necessary. You can collect 100 points in total for this exam. 1. Amdahl’s law determines the speedup S P = P/ (1 + ( P - 1) f ) of a parallel application that has a sequential fraction 0 f 1 . Suppose we have f = 1 5 and P = 6 . (a) What is the speedup of this parallel application? (5 points) (b) What is the parallel efficiency? (5 points) 2. Consider a perfectly parallelizable program with computation time t comp = t/P , where t = 100 seconds. Suppose the communication time of this program linearly increases with increasing number of processors t comm = 0 . 01 · P seconds. (a) Determine all P 1 such that t comp t comm , that is, the range of P for which the computation time dominates the communication time. (6 points) (b) Assuming that the sequential program runs in the same time as t comp for P = 1 , that is t s = t/P = 100 / 1 seconds, what is the speedup S P and parallel efficiency E P when t comp = t comm ? (6 points) 1
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3. Consider the following machine instruction sequence:
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CIS5930midterm08 - HPC Midterm Exam Fall 2008(Please print Name Put the answers on these sheets Use additional sheets when necessary You can

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