University at Buffalo
The State University of New York
CCR
Center for
Computational Research
Amdahl’s Law Example
nSerial
Program
qtA = 2 minutes, tB = 98 minutes
mtserial =
tA + tB =
100 minutes
nParallel
Implementation
qParallelize
step B
mtparallel =
tA + tB/N
nSpeedup
qS = 100 min/
(2 min + 98 min/N)
Observed Speedup
N Sideal Sobs
1 1 1
2 2 2
10
10 8
50 50 25
100
100 34
1000 1000 48