PLease solve and give a full solution A designer wants to improve the overall pe

Question

PLease solve and give a full solution

A designer wants to improve the overall performance of a given machine with respect to a target benchmark suite, and is considering an enhancement X that applies to 50% of the original dynamically-executed instructions, and speeds each of them up by a factor of 3. The designer's manager has some concerns about the complexity and the cost-effectiveness of X and suggests that the designer should consider an alternative enhancement Y. Enhancement Y, if applied only to some (as yet unknown) fraction of the original dynamically-executed instructions, would make them only 75% faster. Determine what percentage of all dynamically-executed instructions should be optimized using enhancement Y in order to achieve the same overall speedup as obtained using enhancement X. (Note: Dynamically-executed instructions are those instructions that arc actually executed when running the application. You can safely assume that in this case Amdahl's Law can be applied to solve this problem. )

Explanation / Answer

We will use Amdahl’s Law for this problem. Execution time after improvement = (Execution time affected by improvement)/(Amount of Improvement) + Execution time unaffected Execution Time using X = (50)/3 + (100-50) = 66.67 The speedup is given by = (100)/66.67 = 1.5 Let the percentage of dynamically executed instructions to which Y is to be applied be x. Execution Time using Y = (x)/1.75 + (100-x) SpeedUp = (100)/(Execution Time using Y) = 1.5 Solving for x, we get x = 77.78

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