DerekChiou_EE360N_Spring2010_Lecture24

DerekChiou_EE360N_Sp - Lecture 24 Performance Evaluation and Parallel Computing Evaluation and Parallel Computing(I Prof Derek Chiou University of

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Lecture 24: Performance valuation and Parallel Computing Evaluation and Parallel Computing (I) Prof. Derek Chiou University of Texas at Austin © Derek Chiou 1
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Test of size nnouncements Announcements z No office hours today or tomorrow et me know if anyone is interested in office hours Wednesday z Let me know if anyone is interested in office hours Wednesday after class z Exam 2 is graded z TAs have the exams 4/26/2010 © Derek Chiou: EE360N: Lecture 24 2
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Test of size ecap and Outline Recap and Outline z Recap inish up branch prediction z Finish up branch prediction z Started on vector machines z Outline z Finish up vector machines z Performance measurement 4/26/2010 © Derek Chiou: EE360N: Lecture 24 3
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Test of size ad Ways to Compare Performance Bad Ways to Compare Performance z Apples and Oranges z Lightly loaded machine versus production machine z Sometimes hard to avoid z Who gets the credit z Too many variables (changed compiler, algorithm, micro- rchitecture) architecture) z Bad/varying base-line z Compare against bad case (unoptimized code, bad algorithm for machine) z Changing the base-line through the paper z Choice of benchmarks z “embarrassing parallel” versus “pleasingly parallel” z Overstates importance of some set of features z No branches, no floating point, etc. z Small 4/26/2010 © Derek Chiou: EE360N: Lecture 24 4 z Small footprint, fit in cache
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Test of size Single Comparable Performance Number A Single Comparable Performance Number z Want a single performance number for a machine z Run several benchmarks ow are the results aggregated together? z How are the results aggregated together? z Averaging speedups? ew Machine runs A in 1 second B in 2 seconds z New Machine runs A in 1 second, B in 2 seconds z Reference Machine runs A in 2 seconds, B in 1 second z Speedup for A is 2/1 and for B is ½ z What is overall performance of New Machine? z Does average speedup give a number that can be compared? 4/26/2010 © Derek Chiou: EE360N: Lecture 24 5
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Test of size Single Comparable Performance Number A Single Comparable Performance Number z Want a single performance number for a machine z Run several benchmarks ow are the results aggregated together? z How are the results aggregated together? z Averaging speedups? ew Machine runs A in 1 second B in 2 seconds z New Machine runs A in 1 second, B in 2 seconds z Reference Machine runs A in 2 seconds, B in 1 second z Speedup for A is 2/1 and for B is ½ z What is overall performance of New Machine? z Does average speedup give a number that can be compared? (2 + ½) = 1 25 Average speedup of old machine is 1 4/26/2010 © Derek Chiou: EE360N: Lecture 24 6 z ½(2 + ½) = 1.25! Average speedup of old machine is 1.
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Test of size ggregating Performance Numbers Aggregating Performance Numbers rithmetic Mean a N i Which one to use?
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This note was uploaded on 09/23/2010 for the course EE 360n taught by Professor Staff during the Spring '08 term at University of Texas at Austin.

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DerekChiou_EE360N_Sp - Lecture 24 Performance Evaluation and Parallel Computing Evaluation and Parallel Computing(I Prof Derek Chiou University of

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