CS3421 Problem Set 4

Performance Analysis

  1. What is the cycle time, in nsec, of a machine with a clock speed of 200 MHz?

  2. What is the cycle time, in μsec, of a machine with a clock speed of 100,000 Hz?

  3. What is the cycle time, in nsec, of a machine with a clock speed of 2.5 GHz?

  4. What is the clock speed, in MHz of a machine with a cycle time of 10 nsec?

  5. What is the clock speed, in GHz of a machine with a cycle time of 0.1 nsec?

  6. Suppose two different machines execute the same program compiled by the same compiler on the same data set. If machine A has an average CPI of 2.4 and a cycle time of 0.5 nsec and machine B has an average CPI of 3.1 and a cycle time of 0.4 nsec, which machine is faster?

  7. What is the (average) CPI under the following conditions:

  8. In the above example, suppose the compiler group releases a new optimizing compiler that changes the relative frequencies of the instructions executed to the following:

    Assuming nothing else has changed, how many times faster (or slower) is the program/data set with new compiler versus the old?

  9. The processor your design group designed and your company now sells runs at 2.0 GHz. The marketing department comes to you and says your competitor will be releasing a processor with a 2.5 GHz clock speed and wants you to design a new processor with that same clock speed. Assuming the only thing you can change is the CPI, which in your current processor is 2.0, what new CPI must you get in order for your new processor to be equally fast as your current one.

  10. What is the difference between CPU time and elapsed time?