Problem $4$:

Assume that multiply instructions take $12$ cycles and account for $15\%$ of the instructions in a typical program, and

that the other $85\%$ of the instructions require an average of $2$ cycles for each instruction. Your hardware engineering

team has indicated that it would be possible to reduce the number of cycles required for multiplication to $6,$ but that

this reduction will require a $20\%$ increase in the cycle time. Nothing else would be affected by the change.

a$.$ Before reducing the CPI of multiplication instructions, what percentage of time does the CPU spend doing

multiplication?

b$.$ Should the hardware engineers proceed with the suggested modification? To answer this question,

compute the speedup achieved by implementing the suggested modification using the CPU performance

equation.

c$.$ Show that the same result can be obtained using Amdahl's law.