Lect07 - Heike Jagode jagode@eecs.utk.edu With slides from...

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Unformatted text preview: Heike Jagode jagode@eecs.utk.edu With slides from Karl Fuerlinger, Andreas Knuepfer, Shirley Moore, Sameer Shende, Felix Wolf and others. 2/24/10 2/24/10 2 2/24/10 3 Think carefully about the prevalent idea that only delivering results counts as acceptable performance If you don’t reach the objectives, maybe you have not performed well enough? The idea that the design of software consists of is NOT simply implementing it Instead, it consists of designing its functional aspects first, then implementing, and finally trying to improve the low-quality product of this procedure Simply, getting a job done? Producing results that you aimed at? Nothing else matters? Basically, solving a problem themed: “hack now, fix later”? As long as we don’t know what Performance is, it will produce confusion and frustration 2/24/10 4 • Domenico Ferrari (1986): “The study of performance evaluation as an independent subject has sometimes caused researchers in the area to lose contact with reality.” • Why is it that performance evaluation is by no means an integrated and natural part of software development? o The primary duty of software developers is to create functionally correct programs! o Performance evaluation tends to be optional Some people compare it to the freestyle event in ice-skating o Raj Jain (1991) “Contrary to common belief, performance evaluation is an art. ... Like artist, each analyst has a unique style. Given the sample problem, two analysts may choose different performance metrics and evaluation methodologies.” … but even they need tools! 2/24/10 5 Performance Analysis is important: • Large investments in HPC systems o Procurement costs: ~$40 Mio o Operational costs: ~$5 Mio per year o Electricity costs: 1 MW / year ~$1 Mio • Efficient usage is important because of expensive and limited resources • Scalability is important to achieve next bigger simulation • Performance analysis: Get highest performance for a given cost • „Performance Analyst“: Anyone who is associated with computer systems, • i.e. system engineers, computer scientists, application delevopers and of course users 2/24/10 6 2/24/10 7 Performance Optimization cycle: Measure & Analyze: • Have an optimization phase • just like testing & debugging phase • Do profiling and tracing • Use tools! • avoid do-it-yourself with printf solutions • … seriously! Usage / Production Measure Analyze Modify / Tune functionally complete and correct program complete, correct and well-performing program Instrumentation Code Development 2/24/10 8 Profiling • Records aggregated information of performance metrics • Number of times a routine was invoked • Exclusive, inclusive time/counts spent executing it • Number of instrumented child routines invoked, etc....
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Lect07 - Heike Jagode jagode@eecs.utk.edu With slides from...

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