lecture_4 - Lecture 4 • Accessing and Understanding...

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Unformatted text preview: Lecture 4 • Accessing and Understanding Performance 1 Performance ¡ Why do we care about performance evaluation? ¢ Purchasing perspective ¡ given a collection of machines, which has the ¢ best performance ? ¢ least cost ? ¢ best performance / cost ? ¢ Design perspective ¡ faced with design options, which has the est performance improvement ? ¢ best performance improvement ? ¢ least cost ? ¢ best performance / cost ? ¡ How to measure, report, and summarize performance? ¢ Performance metric enchmark 2 ¢ Benchmark Which of these airplanes has the best performance? Airplane Passenger Cruising range Cruising speed Passenger throughput Capacity (miles) (m.p.h.) (passengers x m.p.h.) Boeing 777 375 4630 610 228,750 Boeing 747 470 4150 610 286,700 BAC/Sud Concorde 132 4000 1350 178,200 hat metric defines performance? Douglas DC-8-50 146 8720 544 79,424 • What metric defines performance? • Capacity, cruising range, or speed? • peed Speed • Taking one passenger from one point to another in the least time 3 • Transporting 450 passengers from one point to another Two Notions of “ Performance ” ¡ Response Time (latency) — How long does it take for my job to run? ow long does it take to execute a job? — How long does it take to execute a job? — How long must I wait for the database query? hroughput ¡ Throughput — How many jobs can the machine run at once? — What is the average execution rate? — How much work is getting done? ¡ If we upgrade a machine with a new processor what do we increase? ¡ If we add a new machine to the lab what do we increase ? 4 efinitions Definitions ¡ Performance is in units of things-per-second ¢ bigger is better we are primarily concerned with response time ¡ If we are primarily concerned with response time ¢ performance (x) = 1 execution time(x) _ " X is n times faster than Y" means X is n times faster than Y means Performance(X) Execution_Time (Y) n = ---------------------- = ------------------------- Performance(Y) Execution_Time (X) 5 hich one is faster? Concorde or Boeing 747 W c s s ? c d g • Response Time of Concorde vs. Boeing 747? • Concord is 1350 mph / 610 mph = 2.2 times faster • Throughput of Concorde vs. Boeing 747 ? oeing is 286 700 pmph / 178 200 pmph = 1 6 “ mes faster ” • Boeing is 286,700 pmph / 178,200 pmph = 1.6 times faster • Boeing is 1.6 times ( “ 60% ” ) faster in terms of throughput • Concord is 2.2 times ( “ 120% ” ) faster in terms of flying time 6 Example of Relative Performance ¡ If computer A runs a program in 10 seconds and computer B runs the same program in 15 seconds, how uch faster is A than B? much faster is A than B? ) Performance erformance = (1) Performance A /Performance B n (2) Performance ratio: 15/10 = 1.5 ) A is 1 5 times faster than B (3) A is 1.5 times faster than B We will focus primarily on execution time for a single job !...
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lecture_4 - Lecture 4 • Accessing and Understanding...

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