1) What would be the execution time for a program containing 2.,000,000 instruct

Question

1) What would be the execution time for a program containing 2.,000,000 instructions if the processor clock were running at 8 MHz and each instruction took four clock cycles?

2) Asman architect reimplements a given instruction-set architecture, halving the CPI for 50% of the instructions while increasing the clock cycle time of the processor by 10%. How much faster is the new implementation, compared with the original? Assume that all instructions are equally likely to be used in determining the execution time of any program.

please help me both questions. thank you

Explanation / Answer

Answer 1 )

Execution time of program = number of instructions * average CPI for a program / CPU clock cycle

number of instructions are = 2,000,000
Average CPI(cycles per instructions) for program = 4 clock cycles
CPU clock cycle = 8 Mhz

so execution time of a program = 2,000,000 * 4 / 8,000,000

execution time = 1 second

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Answer 2)  Asman architect reimplements a given instruction-set architecture. They halved the CPI for 50% of the instructions and increased clock cycle time of the proccessor by 10%

We know that CPI =   the average number of clock cycles per instruction
so each instruction will take 2 clock cycles
hence, average CPI for a program is = 2 clock cycles

CPU clock cycle time is increased by 10%
so new clock cycle time is = 8 + 0.8
i.e. 8.8 MHz

So Execution time for newly implemented instructions-set architecture will be :

2,000,000 * 2 / 8,800,000 = 0.45 seconds

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newly implemented instructions-set architecture takes only 0.45 seconds to run the same program
Hence, it takes 0.55 less seconds to finish a task and it is faster than previous design.

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