Efficiency ? = Speed Up S / P (Number of Processors) |
Overhead fcomm = (P TP - T1) / T1 = 1/ ? - 1 |
As fcomm linear in TP, overhead effects tend to be additive |
In 2D Jacobi example fcomm = tcomm/(?n tfloat) |
While efficiency takes approximate form ? ? 1 - tcomm/(?n tfloat) valid when overhead is small |
As expected efficiency is < 1 corresponding to speedup being < P |