Assume a program requires the execution of 50 x 10^6 FP instructions, 110 x 10^6 INT instructions, 80 x 10^6 Load/Store (L/S) instructions and 16 x 10^6 branch instructions. The CPI for each type of instruction is 1, 1, 4 and 2, respectively. Assume that the processor has a 2 GHz clock rate. By how much must we improve the CPI of FP instructions if we want the program to run two times faster?

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

answer:

a

explanation:

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