Skip to content
Snippets Groups Projects
Commit 068e9098 authored by Stefania Ciliberti's avatar Stefania Ciliberti
Browse files

add MPI3 option

parent 8b512a73
No related branches found
No related tags found
No related merge requests found
......@@ -265,6 +265,13 @@ The data exchanges between processors are required at the very place where
lateral domain boundary conditions are set in the mono-domain computation:
the \rou{lbc\_lnk} routine (found in \mdl{lbclnk} module) which manages such conditions is interfaced with
routines found in \mdl{lib\_mpp} module.
From the NEMO4.2 release, a new communication strategy has been introduced to preserve performance efficiency
by reducing communication time, namely the MPI3 neighborhood collective communications.
It provides a way to have sub-communicators used to perform collective communications only among neighborhood.
A single MPI message is needed to be built for all neighbours instead of 4 different messages before calling the collective.
The new communication approach can be selected by setting the value of \np{nn_comm}{nn\_comm} parameter, defined in \nam{mpp}{mpp} namelist.
\np{nn_comm}{nn\_comm}=1 activates the point to point communications.
Any value other than 1 (usually \np{nn_comm}{nn\_comm}=2) can be used to select the collective communications.
The output file \textit{communication\_report.txt} provides the list of which routines do how
many communications during 1 time step of the model.\\
......
0% Loading or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment