Answer:
13 Seconds
Explanation:
Let P1 denotes the performance when old compiler was used to write the C application and P2 denotes the performance when the application is compiled with the new compiler.
CPU time measures of processor performance which is the execution time from the start till end of the program application.
CPU Time of P1 = Instruction count * Average cycles per instruction * Clock cycle time
CPU Time (P1) = I * CPI * T
20 seconds = I * CPI * T
Clock cycle time (T) is also called Clock Rate. So
CPU Time of P1 = Instruction count * Average cycles per instruction * Clock Rate
ClockRate = CPU Time of P1 / Instruction count * Average cycles per instruction
Clock Rate = 20 seconds / (I * CPI )
number of instructions of application = 0.5
Increased CPI = 1.3
The performance of application when compiled with new compiler:
CPU Time of P2 = Instructions count * Cycles per instruction * Clock Rate
= I * CPI * Clock rate
= 0.5 * 1.3 * Clock rate
As Clock Rate = 20 seconds / (I * CPI ) So
CPU Time of P2 = (0.5 I ) * 1.3 CPI) * 20/ ( I * CPI)
= 0.5 * 1.3 * 20
= 13 seconds
So the execution time of application when compiled with new compiler is 13 seconds.
