Compiling GPU-enabled MPAS-A

Compilation of the GPU-enabled MPAS-Atmosphere code is different from compiling a standard release of MPAS-Atmosphere in only one respect: The option OPENACC=true must be added to the compilation command. For example:

make -j 4 pgi CORE=atmosphere USE_PIO2=true OPENACC=true

Through this specification in the build command, additional compiler flags will be added. At present, these include -Mnofma -acc -ta=tesla:cc70 -Minfo=accel.

As described in Supported Platforms, only PGI compilers are supported; accordingly, the use of OPENACC=true only adds additional flags for the pgi build target.

If the model is successfully compiled for execution on GPUs, the build summary should indicate that OpenACC was enabled:

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MPAS was built with default double-precision reals.
Debugging is off.
Parallel version is on.
Papi libraries are off.
TAU Hooks are off.
MPAS was built without OpenMP support.
MPAS was built with OpenACC enabled.
MPAS was built with .F files.
The native timer interface is being used
Using the PIO 2 library.
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