# OpenMP Communication Efficiency

The OpenMP Communication Efficiency (OpenMP CE) is defined as the quotient of the Hybrid Communication Efficiency (HCE) and the MPI Communication Efficiency (MPI CE) and thereby captures the overhead induced by the OpenMP constructs, which represents threads synchronization and scheduling.

$OpenMP\_CE = \frac{HCE }{MPI\_CE}$

It can be also computed as the maximum of useful compute time (over all processes, threads) divided by the maximum runtime outside of MPI (per process).

$OpenMP\_CE = \frac{Maximum Of Useful Compute Time}{Maximum Runtime Out Of MPI}$

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