Amdahl’s Law Example
n Serial Program
q tA = 2 minutes, tB = 98 minutes
m tserial = tA + tB = 100 minutes
n Parallel Implementation
q Parallelize step B
m tparallel = tA + tB/N
n Speedup
q S = 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