performance - CSE 341 The Role of Performance Defining...

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CSE 341 The Role of Performance Defining Performance c How do we define performance? c If one computer outperforms another, what does that mean? h Clock Speed a CISC vs. RISC h Instructions per Second a CISC vs. RISC h Time to perform specified task(s) a Elapsed a CPU a Note dependence on task! c Consider the following example h Four (4) airplanes are being evaluated to determine which one performs the best. h Let’s consider speed… a Which plane can move 1 person from NYC to Paris the fastest? C Concorde a Which plane can move 400 people from NYC to Paris the fastest? C 747 a Which one performs the best? C Depends upon criteria! c Throughput h Amount of passengers transported over a given time c Additional Metrics h Range h Fuel Efficiency c Throughput vs. Response Time h Throughput a A system administrator may be concerned about throughput h Response Time (Execution Time) a A user may be concerned about response time Airplane Boeing 777 Boeing 747 BAC / Sud Concorde Douglas DC-8-50 Passenger Capacity 375 470 132 146 Cruising Range (miles) 4630 4150 4000 8720 Cruising Speed (mph) 610 610 1350 544 Airplane Boeing 777 Boeing 747 BAC / Sud Concorde Douglas DC-8-50 Passenger Capacity 375 470 132 146 Cruising Range (miles) 4630 4150 4000 8720 Cruising Speed (mph) Passenger Throughput (passengers mph) x 610 228,750 610 1350 544 286,700 178,200 79,424
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c Defining Performance c Relative Performance h X is n times faster than Y c When speaking about relative performance, be careful of wording… h Consider the following a X is n times faster than Y a Y is also n times slower than X h Improving performance or improving execution time usually means… a Increased performance a Decreased execution time Measuring Performance c Example h Runtimes a Computer A = 7.8 seconds a Computer B = 32.2 seconds h Performance a Computer A is 4.1 times faster than computer B c Time h The program that can perform the greatest amount of work in the least amount of time is the fastest. c Execution Time h Seconds per program h Elapsed time h Response time h Includes total time to complete task a Disk/memory accesses a I/O activities a Operating system overhead x x Time Execution 1 e Performanc = x y y x n Time Execution Time Execution e Performanc e Performanc = = x y n Time Execution Time Execution =
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c Timeshared Machines h Optimize throughput a CPU Time or CPU Execution Time C The amount of time the processor spends computing for specified task Does not include waiting for I/O or running other programs C Two components User CPU time (spent in program) System CPU time (spent in operating system) C Often difficult to differentiate between the two components a Response time experienced by user is elapsed time C NOT CPU time h System Performance a Elapsed time on an unloaded system h CPU Performance a CPU time c Unix time command h Provides a breakdown of the time required to perform a task h Output a User time a System time a Elapsed time a Percentage of elapsed time that is CPU time
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performance - CSE 341 The Role of Performance Defining...

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