Fundamentals of Quantitative Design and Analysis - Computer Architecture: A Quantitative Approach - page 66

shown, the Sun Fire T2000 is clearly superior. What other factors might be important and
thus cause someone to choose the IBM x346 if it were superior in those areas?
FIGURE 1.24 Sun power/performance comparison as selectively reported by Sun .
1.7 [20/20/20/20] <1.6, 1.9> Your company's internal studies show that a single-core system is
suicient for the demand on your processing power; however, you are exploring whether
you could save power by using two cores.
a. [20] <1.9> Assume your application is 80% parallelizable. By how much could you de-
crease the frequency and get the same performance?
b. [20] <1.6> Assume that the voltage may be decreased linearly with the frequency.
Using the equation in Section 1.5 , how much dynamic power would the dual-core sys-
tem require as compared to the single-core system?
c. [20] <1.6, 1.9> Now assume the voltage may not decrease below 25% of the original
voltage. This voltage is referred to as the voltage floor? , and any voltage lower than that
will lose the state. What percent of parallelization gives you a voltage at the voltage
floor?
d. [20] <1.6, 1.9> Using the equation in Section 1.5 , how much dynamic power would the
dual-core system require as compared to the single-core system when taking into ac-
count the voltage floor?
QExercises
1.8 [10/15/15/10/10] <1.4, 1.5> One challenge for architects is that the design created today will
require several years of implementation, verification, and testing before appearing on the
market. This means that the architect must project what the technology will be like several
years in advance. Sometimes, this is difficult to do.
a. [10] <1.4> According to the trend in device scaling observed by Moore's law, the num-
ber of transistors on a chip in 2015 should be how many times the number in 2005?
b. [15] <1.5> The increase in clock rates once mirrored this trend. Had clock rates con-
tinued to climb at the same rate as in the 1990s, approximately how fast would clock
rates be in 2015?
c. [15] <1.5> At the current rate of increase, what are the clock rates now projected to be
in 2015?
d. [10] <1.4> What has limited the rate of growth of the clock rate, and what are architects
doing with the extra transistors now to increase performance?