Question

assume for arithmetic, load/store, and branch instructions, a processor has CPIs of 1, 12, and 5, respectively. Also assume that on a single processor a program requires the execution of 2.56E9 arithmetic instructions, 1.28E9 load/store instructions, and 256 million branch instructions. Assume that each processor has a 2 GHz clock frequency. Assume that, as the program is parallelized to run over multiple cores, the number of arithmetic and load/store instructions per processor is divided by 0.7 × p (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 this program on 1, 2, 4, and 8 processors, and show the relative speedup of the 2, 4, and 8 processors result relative to the single processor result.

Answer 1

Answer:

1 PROCESSOR :

(1 × 2.56 × 10^9) + (12 × 1.28 × 10^9) + (5 × 2.56 × 10^8) / 2 GHz = 9.6 s

2 PROCESSORS :

(1×2.56×10^9)+(12×1.28×10^9)/0.7×2 + (5 × 2.56 × 10^8) / 2 GHz = 7.04 s

Speed -up is 1.36

4 PROCESSORS :

(1×2.56×10^9)+(12×1.28×10^9)/0.7×4 + (5 × 2.56 × 10^8) / 2 GHz = 3.84 s

Speed -up is 2.5

5 PROCESSORS :

(1×2.56×10^9)+(12×1.28×10^9)/0.7×8 + (5 × 2.56 × 10^8) / 2 GHz = 2.24 s

Speed -up is 4.29

Explanation:  

The following formula is used in this answer:

EXECUTION TIME = CLOCK CYCLES / CLOCK RATE

Execution Time is equal to the clock cycle per clock rate