Lecture 04-performance - 1048 Computer Organization Lecture...

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Lecture04 - performance ([email protected]) 4-1 1048: Computer Organization 1048: Computer 1048: Computer Organization Organization Lecture 4 Lecture 4 Assessing and Assessing and Understand Performance Understand Performance
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Lecture04 - performance ([email protected]) 4-2 Performance ? Measure, Report, and Summarize Make intelligent choices See through the marketing hype Key to understanding underlying organizational motivation Why is some hardware better than others for different programs? What factors of system performance are hardware related? (e.g., Do we need a new machine, or a new operating system?) How does the machine's instruction set affect performance?
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Lecture04 - performance ([email protected]) 4-3 Why Study Performance? •C o n f l i c t i n g G o a l s –U s e r • Find the most suitable machine to get the job done at the lowest cost Application-oriented metrics –V e n d o r • Persuade you to buy their machine regardless of your needs H ardware-oriented metrics • Know the vocabulary and understand the issues, so that: – As a user/buyer, you can make better purchasing decisions – As an engineer, you can make better hardware/software design decision
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Lecture04 - performance ([email protected]) 4-4 Example: Two Airplanes Concorde: • Capacity: 100 persons • Range: 6667 km • Cruising speed: 2160 kph (Mach 2) at 60,000 ft 747-400: • Capacity: 400 persons • Range: 11,485 km • Cruising speed: 929 kph at 35,000 ft
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Lecture04 - performance ([email protected]) 4-5 Which is better? • Time to run the task (ExTime) –Ex e c u t i o n t im e , response time , latency • Tasks per day, hour, week, sec, ns … (Performance) –Th r o u gh p u t , bandwidth Plane Boeing 747 BAD/Sud Concodre Speed 610 mph 1350 mph DC to Paris 6.5 hours 3 hours Passengers 470 132 Throughput (pmph) 286,700 178,200 Response time and throughput often are in opposition
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Lecture04 - performance ([email protected]) 4-6 Concluding Remarks • Time of Concorde vs. Boeing 747: – Concord is 1350 mph / 610 mph = 2.2 times faster = 6.5 hours / 3 hours = 2.2 times better • Throughput of Concorde vs. Boeing 747: – Boeing is 286,700 pmph / 178,200 pmph = 1.6 times better • Boeing is 1.6 times (60%) faster in terms of throughput • Concord is 2.2 times (120%) faster in terms of flying time (response time) We will focus on execution time for a single job
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Lecture04 - performance ([email protected]) 4-7 • Performance according to time: => faster is better • If interested in comparing two things: “X is n times faster than Y” means time(X) execution_ 1 e(X) performanc = e(Y) performanc e(X) performanc = n Performance Definition
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Lecture04 - performance ([email protected]) 4-8 What is Time? • Straightforward definition of time: – Total time to complete a task, including disk & memory accesses, I/O activities, OS overhead, … – May include execution time of other programs in a multiprogramming environment – Too many factors involved • Alternative: the time that the processor (CPU) is working only on your program (since multiple processes running at same time)
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This note was uploaded on 08/23/2009 for the course DEE 4641 taught by Professor Cwliu during the Fall '08 term at National Chiao Tung University.

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Lecture 04-performance - 1048 Computer Organization Lecture...

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