OpenMP Region Efficiency

OpenMP Region Efficiency indicates inefficiencies within threads, and can be computed as follows:

$\begin{eqnarray*}OpenMP\; Region\; Efficiency=\frac{avg(time\; in\; useful\; computation\; within\; OpenMP ) + avg( serial\; computation ) }{avg( time\; in\; OpenMP ) + avg( serial\; computation )} \end{eqnarray*}$

Where average time in OpenMP and average serial computation are computed as weighted arithmetic mean. If number of threads is equal across processes average time in OpenMP and average serial computation can be computed as ordinary arithmetic mean.