# MPI Communication Efficiency

The MPI Communication Efficiency (MPI CE) describes the loss of efficiency in MPI processes communication only considering time outside MPI.

$MPI\_CE = \frac{Maximum Time Outside MPI}{Total Runtime} = \frac{Max(OutMPI_{1,1}, \cdots, OutMPI_{P,1})}{Total Runtime}$

In order to fully understand the formulas, you may also visit the glossary of the metrics terms.