CS312_09s_CH4 - Introduction Why bother with performance?...

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Chapter 4 Performance 2 Introduction Why bother with performance? H/W performance has an overall impact on the entire system. How do we measure performance? Depends how you define performance. So, what is performance? A measure of (a) Execution or response time – How long does it take to execute a program and (b) Throughput – How many programs are executed in a given time Throughput and Response Time Response time Throughput Typically, by b Response time you B Throughput Scenario Response Time b Throughput B Both Replacing the processor in a computer with a faster version. c c c c Adding additional processors to a system that uses multiple processors for separate tasks. Performance vs Execution Time To maximize performance, must minimize execution time What does "X is n times faster than Y" mean? x x time Execution e Performanc 1 = X Y Y X time Execution time Execution n e Performanc e Performanc = = Example If machine A runs a program in 10 seconds and machine B runs the same program in 15 seconds, how much faster is A than B? A: A is 1.5 times faster than B
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This note was uploaded on 08/26/2009 for the course CS 312 taught by Professor Tornaritis,s during the Spring '08 term at Southern Illinois University Edwardsville.

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CS312_09s_CH4 - Introduction Why bother with performance?...

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