S=(1−α)P+α Gustafson's law states that the speed up, S, of a computation on P processors is given by the equation where α is a known constant related to the parallelizability. Which of the following expressions equals the increase in the number of processors needed for the speedup to increase by 1? Choose 1 answer:(A) 1−α(B) α−1α(C) 1−α1(D) α
Q. S=(1−α)P+α Gustafson's law states that the speed up, S, of a computation on P processors is given by the equation where α is a known constant related to the parallelizability. Which of the following expressions equals the increase in the number of processors needed for the speedup to increase by 1? Choose 1 answer:(A) 1−α(B) α−1α(C) 1−α1(D) α
Given Gustafson's Law: We are given Gustafson's law in the form S=(1−α)P+α. We want to find the increase in the number of processors (ΔP) needed for the speedup (S) to increase by 1. Let's denote the initial speedup as S1 and the increased speedup as S2, where S2=S1+1.
Expressing Speedups: First, we express S1 and S2 using Gustafson's law. S1=(1−α)P+α and S2=(1−α)(P+ΔP)+α.
Simplifying Equation: Since S2 is 1 greater than S1, we can write S2=S1+1. Substituting the expressions for S1 and S2, we get (1−α)(P+ΔP)+α=(1−α)P+α+1.
Distributing Terms: Now, we simplify the equation. The α terms on both sides cancel out, leaving us with (1−α)(P+ΔP)=(1−α)P+1.
Canceling Terms: We distribute (1−α) on the left side of the equation: (1−α)P+(1−α)ΔP=(1−α)P+1.
Finding ΔP: The (1−α)P terms on both sides of the equation cancel out, leaving us with (1−α)ΔP=1.
Matching Answer Choice: To find ΔP, we divide both sides of the equation by (1−α): ΔP=(1−α)1.
Matching Answer Choice: To find ΔP, we divide both sides of the equation by (1−α): ΔP=(1−α)1.We look at the answer choices to find the one that matches our expression for ΔP. The correct answer is (C) (1−α)1.
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