csse232_hw2_soln - Fall 2016-2017 CSSE 232 CSSE 232...

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Fall 2016-2017CSSE 232CSSE 232 – Computer Architecture IRose-Hulman Institute of TechnologyComputer Science and Software Engineering DepartmentHomework 2 Solutions1. (20 points) In this exercise, we’ll examine quantitatively the pros and cons of addingan addressing mode toMIPSthat allows arithmetic instructions to directly accessmemory, as is found on the IA-32. The primary benefit is that fewer instructions willbe executed because we won’t have to first load a register. The primary disadvantageis that the cycle time will have to increase to account for the additional time to readmemory. Consider adding a new instruction:addm $t2, 100($t3)# $t2 = $t2 + Memory[$t3+100]Assume that the new instruction will cause the cycle time to increase by 10%. Use theinstruction frequencies for the SPEC2006int from Figure 2.45 on page 163 and assumethat 2/3 of the data transfers are loads and the rest are stores. Assume that the newinstruction affects only the clock speed, not the average CPI of the machine. Whatpercentage of the loads must be eliminated for the machine with the new instructionto have at least the same performance?
5 September 2016Page 1
Fall 2016-2017CSSE 232

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