Answer:
We can not improve CPI of FP instructions when we run the program two times faster because it would be negative.
Explanation:
Processor clock rate = 2 GHz
Execution Time = ∑
Clock cycles can be determined using following formula
Clock cycles = ( x No. FP instructions )+ (
x No. INT instructions) + (
x No. L/S instructions ) + (
x No. branch instructions)
Clock cycles = ( 50 x x 1) + ( 110 x
x 1) + ( 80 x
x 4) + ( 16 x
x 2)
Clock cycles = 512 x 10⁶
So,Initial Execution time for FP instructions is,
=
Initial execution Time = 256 x 10⁻³
For 16 processors ,
clock cycle = 512 x 10⁶
Execution Time = 256 x 10⁻³
To run the program two times faster, half the number of clock cycles
( )= (
x No. FP instructions )+ (
x No. INT instructions) + (
x No. L/S instructions ) + (
x No. branch instructions)
x No. FP instructions = (
) -[ (
x No. INT instructions) + (
x No. L/S instructions ) + (
x No. branch instructions)]
x 50 x
= (
) - [ ( 110 x
x 1) + ( 80 x
x 4) + ( 16 x
x 2)]
x 50 x
= - 206 x
= - 206 x
/ 50 x
= - 4.12 < 0