Exercise 1.13 Suppose that we are developing a new version of the AMD Barcelona processor with a 4 GHz clock rate. We have added some additional instructions to the instruction set in such a way that the number of instructions has been reduced by 15% from the values shown for each benchmark in Exercise 1.12. The execution times obtained are shown in the following table.

Name Execution time (seconds) Reference time (seconds) SPECratio

a. perl 450 9770 21.7

b. mcf 1150 9120 7.9 1.13.1 [10] <1.8> Find the new CPI.

1.13.2 [10] <1.8> In general, these CPI values are larger than those obtained in previous exercises for the same benchmarks. This is due mainly to the clock rate used in both cases, 3 GHz and 4 GHz. Determine whether the increase in the CPI is similar to that of the clock rate. If they are dissimilar, why?

1.13.3 [5] <1.8>By how much has the CPU time been reduced?

The following table shows data for further benchmarks.

Name Execution time (seconds) CPI Clock rate

a. sjeng 820 0.96 3 GHz

b. omnetpp 580 2.94 3 GHz 1.13.4 [10] <1.8> If the execution time is reduced by an additional 10% without affecting the CPI and with a clock rate of 4 GHz, determine the number of instructions.
1.13.5 [10] <1.8> Determine the clock rate required to give a further 10% reduction in CPU time while maintaining the number of instructions and CPI unchanged.
1.13.6 [10] <1.8> Determine the clock rate if the CPI is reduced by 15% and the CPU time by 20% while the number of instructions is unchanged.