Question

Suppose that we can improve the floating point instruction performance of machine by a factor of 15 (the same floating point instructions run 15 times faster on this new machine). What percent of the instructions must be floating point to achieve a Speedup of at least 4?

Answer 1

Answer to the following question is 80.36.

Explanation:

We use an Amdahl’s Law.

Let x be the percentage of a floating-point instruction.

Since, the speedup = 4,

if the program executed 100 cycles then, this program will runs 100/4 = 25 cycles

\frac{100}{4} = \frac{x}{15} + (100-x)

Solve x, we get:

x = 80.36