Cube GUI User Guide  (CubeGUI 4.8.2, revision 7895e762)
Introduction in Cube GUI and its usage

MPI Communication Efficiency

MPI Communication Efficiency (CommE) can be evaluated directly by following formula:

\begin{eqnarray*}CommE=\frac{max(time\; in\; OpenMP + serial\; computation\; time)}{max(runtime)} \end{eqnarray*}

CommE identifies when code is inefficient because it spends a large amount of time communicating rather than performing useful computations. CommE is composed of two additional metrics that reflect two causes of excessive time within communication:

These are measured using Serialisation Efficiency and Transfer Efficiency. Combination of these two sub-metrics gives us Communication Efficiency:

CommE = Serialisation EfficiencyTransfer Efficiency

To obtain these two sub-metrics we need to perform Scalasca trace analysis which identifies serialisations and inefficient communication patterns.


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