Answer the following questions. Show your calculations to get full points. 1. Yo

Question

Answer the following questions.

Show your calculations to get full points.

1. Your favorite program runs in 12 seconds on computer X, which has a 2.2 GHz clock. We are trying to help a computer designer build a computer, Y, which will run this program in 5 seconds. The designer has determined that a substantial increase in the clock rate is possible, but this increase will affect the rest of the CPU design, causing computer Y to require 1.5 times as many clock periods as computer X for this program. What clock speed should we tell the designer to target? (2 points)

2. Suppose there are two implementations of the same instruction set architecture. Computer X has a clock cycle time of 125 ps and a CPI of 2.0, and computer Y has a clock cycle time of 200 ps and a CPI of 1.2 for the same program. Which computer is faster for this program and by how much? (2 points)

Explanation / Answer

Solution 1

(1)CPU execute timeX
= CPU clock cyclesX/ Clock rateX
= 12 sec = CPU clock cyclesX/ 2.2GHz
CPU clock cyclesX=2.2GHz x 12sec =26.4G cycles
(2)CPU execute timeY
= 1.5 x CPU clock cyclesX/ Clock rateY
= 5 sec =1.5x26.4G cycles / Clock rateY
CPU rateY= 1.5x26.4G cycles / 5sec =7.92GHz

The programmer should target 7.92GHz clock speed.

Solution 2

Lets assume instruction count = I

Execution time of X = 125ps * 2.0 * I = 250I ps

Execution time of Y = 200ps * 1.2 * I = 240I ps

We can clearly see that Execution time of X is more than that of Y.

So, Computer Y is faster than X.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.