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Self-test 1.3

26 March, 2015 - 14:18

Program X has the following characteristics:

  • 20% of the instructions are memory operations;
  • 50% of the instructions are performing integer calculations;
  • 30% of the instructions are performing floating-point calculations.

Program X is compiled and run on machine A with the following characteristics:

  • CPI of memory operations = 2;
  • CPI of integer operations = 1;
  • CPI of floating-point operations = 4.
  1. Calculate the average CPI of the program X.
  2. Calculate the CPU time of program X if X has 150 million instructions and machine A has a 200 MHz processor.

Now assume that a floating-point co-processor has been added to the system, and the CPI of floating-point operations is reduced to 2. Next:

  1. Calculate the performance improvement (in percentages) of the floating-point operations.
  2. Calculate the performance improvement (in percentages) of program X.
  3. What is the clock rate required in order for the system to execute program X without the float-point co-processor and achieve the same performance?