ECE3055 Computer Architecture and Operating Systems Lecture 2 Performance. Prof. Hsien-Hsin Sean Lee School of Electrical and Computer Engineering Georgia Institute of Technology. Performance. Measure, Report, and Summarize Make intelligent choices See through the marketing hype
ECE3055 Computer Architecture and Operating SystemsLecture 2 Performance
Prof. Hsien-Hsin Sean Lee
School of Electrical and Computer Engineering
Georgia Institute of Technology
the best performance?
Airplane Passengers Range (mi) Speed (mph)
Boeing 737-100 101 630 598
Boeing 747 470 4150 610
BAC/Sud Concorde 132 4000 1350
Douglas DC-8-50 146 8720 544
So, to improve performance (everything else being equal) you can either________ the # of required cycles for a program, or________ the clock cycle time or, said another way, ________ the clock rate.
6thHow many cycles are required for a program?
This assumption is incorrect, different instructions take different amounts of time on different machines.Why?hint: remember that these are machine instructions, not lines of C code
Source: Sun Microsystems
W1100z uses AMD Opteron
100 series CPU
Does doubling the clock rate double the performance?
Can a machine with a slower clock rate have better performance?
Execution Time After Improvement = Execution Time Unaffected +( Execution Time Affected / Amount of Improvement )
(1 - f)
(1 - f)
f / PAmdahl’s Law
Perfnew / Perfold =Exec_timeold / Exec_timenew =
How about making it 5 times faster?