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A computer executes a benchmark which has $25{10}^6$INT instructions, $55{10}^{6}FP$ instructions, $40x$

${10}^6\frac{L}{S}$ instructions and $10{10}^6$ Branch instructions. The CPI for each type of instruction is $4,16,12,$

and $8,$ respectively. Assume that the processor has a $2GHz$ clock rate.

a$)$ If the program has to run two times faster with the same clock rate, by how much must the CPI of

FP instructions be improved?

b$)$ What percentage of the code of a program has to be parallelizable and what percentage can be run

sequentially on a $128$ processors system to achieve a speedup of $20?$