Quiz3Soln - per program Computer 1 is now the fastest...

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CDA3101 Quiz 3 Last Name ____________________ Fall 2006 First Name ____________________ Time: 10 minutes 1. Suppose 3 computers are run through a series of benchmarks that test game, office, and scientific applications, yielding the following execution times for each benchmark: Times (in seconds) Games Office Apps Science Apps Computer 1 15 20 30 Computer 2 30 10 50 Computer 3 20 30 1 Suppose I play games 10 times as much as use office apps, and I never use Science apps. Compute the weighted average time for this usage for each computer. Which computer is fastest ? How much faster is it than the other two computers. Computer 1: (10(15) + 1(20) + 0(30)) / 11 = 170 / 11 = 15 seconds per program Computer 2: (10(30) + 1(10) + 0(50)) / 11 = 310 / 11 = 28 seconds per program Computer 3: (10(20) + 1(30) + 0(1)) / 11 = 230 / 11 = 21 seconds
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Unformatted text preview: per program Computer 1 is now the fastest according to the weighted arithmetic mean. Computer 1 is 28/15 times faster than Computer 2 or (28/15-1) * 100% = 1300/15% = 87% faster . Computer 1 is 21/15 times faster than Computer 3 or (21/15-1) * 100% = 600/15% = 40% faster . 2. Suppose a computer runs at 2GHz. This computer runs an MPEG-4 video encoder that takes 1 billion instructions, and has the following distribution of instructions. How long does it take the program to complete? 20% Floating point CPI = 3 10% Integer CPI = 1 30% Load CPI = 2 20% Store CPI = 1 15% Branches CPI = 4 5% Other CPI = 1.5 Effective CPI = 20% (3) + 10% (1) + 30% (2) + 20% (1) + 15% (4) + 5% (1.5) = 0.6 + 0.1 + 0.6 + 0.2 + 0.6 + 0.075 = 2.175 CPU Time = IC * CPI * CCT = (10 9 instr) * 2.175 * (5 x 10-10 seconds)...
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