Assume for arithmetic, load/store, and branch instructions, a processor has CPIs for 1, 12, and 5
respectively. Also assume that on a single processor a program requires the execution of 2.56*10^9
arithmetic instructions, 1.28*10^9 load/store instructions, and 256 million branch instructions. Assume
that each processor has a 2GHz clock frequency. Assume that, as the program is parallelized to run over
multiple cores, the number of arithmetic and load/store instruction per processor is divided by 0.7xp
(where p is the number of processors) but the number of branch instructions per processor remains the
same.
a- Find the total execution time for the program on 1,2,4, and 8 processors, and show the relative
speedup of the 2,4, and 8 processor result relative to single processor result.
b- If the CPI of the arithmetic instruction was doubled, what would be the impact be on the
execution time of the program on 1,2,4, and 8 processors?
c- To what should the CPI of load/store instructions be reduced in order for a single processor to
match the performance of four processors using the original CPI?