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/* Copyright 2020 Axel Huebl
*
* This file is part of WarpX.
*
* License: BSD-3-Clause-LBNL
*/
#include "MPIInitHelpers.H"
#include <AMReX_Config.H>
#include <AMReX_ParallelDescriptor.H>
#include <AMReX_Print.H>
#if defined(AMREX_USE_MPI)
# include <mpi.h>
#endif
#include <string>
#include <utility>
namespace utils
{
std::pair< int, int >
warpx_mpi_init (int argc, char* argv[])
{
int thread_required = -1;
int thread_provided = -1;
#ifdef AMREX_USE_MPI
thread_required = MPI_THREAD_SINGLE; // equiv. to MPI_Init
# ifdef AMREX_USE_OMP
thread_required = MPI_THREAD_FUNNELED;
# endif
# ifdef AMREX_MPI_THREAD_MULTIPLE // i.e. for async_io
thread_required = MPI_THREAD_MULTIPLE;
# endif
MPI_Init_thread(&argc, &argv, thread_required, &thread_provided);
#else
amrex::ignore_unused(argc, argv);
#endif
return std::make_pair(thread_required, thread_provided);
}
void
warpx_check_mpi_thread_level (std::pair< int, int > const mpi_thread_levels)
{
#ifdef AMREX_USE_MPI
auto const thread_required = mpi_thread_levels.first;
auto const thread_provided = mpi_thread_levels.second;
auto mtn = amrex::ParallelDescriptor::mpi_level_to_string;
if( thread_provided < thread_required )
amrex::Print() << "WARNING: Provided MPI thread safety level ("
<< mtn(thread_provided) << ") is LOWER than requested "
<< mtn(thread_required) << "). This might lead to undefined "
<< "results in asynchronous operations (e.g. async_io).";
if( thread_provided > thread_required )
amrex::Print() << "NOTE: Provided MPI thread safety level ("
<< mtn(thread_provided) << ") is stricter than requested "
<< mtn(thread_required) << "). This might reduce multi-node "
<< "communication performance.";
#else
amrex::ignore_unused(mpi_thread_levels);
#endif
}
} // namespace utils
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