BaseLib::MPI Namespace Reference

Classes
struct	Mpi
struct	Setup

Functions
template<typename T >
constexpr MPI_Datatype	mpiType ()
template<typename T >
static std::vector< T >	allgather (T const &value, Mpi const &mpi)
template<typename T >
static std::vector< T >	allgather (std::vector< T > const &vector, Mpi const &mpi)
template<typename T >
static T	allreduce (T const &value, MPI_Op const &mpi_op, Mpi const &mpi)
template<typename T >
static std::vector< T >	allreduce (std::vector< T > const &vector, MPI_Op const &mpi_op, Mpi const &mpi)
template<typename T >
static void	allreduceInplace (std::vector< T > &vector, MPI_Op const &mpi_op, Mpi const &mpi)
template<typename T >
static std::vector< int >	allgatherv (std::span< T > const send_buffer, std::vector< std::remove_const_t< T > > &receive_buffer, Mpi const &mpi)
static int	reduceMin (int const val)

Function Documentation

allgather() [1/2]

template<typename T >

static std::vector< T > BaseLib::MPI::allgather ( std::vector< T > const & vector, Mpi const & mpi )

static

Definition at line 113 of file MPI.h.

{
    std::size_t const size = vector.size();
    // Flat in memory over all ranks;
    std::vector<T> result(mpi.size * size);
 
    std::copy_n(vector.begin(), size, &result[mpi.rank * size]);
 
    MPI_Allgather(&result[mpi.rank * size], size, mpiType<T>(), result.data(),
                  size, mpiType<T>(), mpi.communicator);
 
    return result;
}

References BaseLib::MPI::Mpi::communicator, mpiType(), BaseLib::MPI::Mpi::rank, and BaseLib::MPI::Mpi::size.

allgather() [2/2]

template<typename T >

static std::vector< T > BaseLib::MPI::allgather ( T const & value, Mpi const & mpi )

static

Definition at line 100 of file MPI.h.

{
    std::vector<T> result(mpi.size);
 
    result[mpi.rank] = value;
 
    MPI_Allgather(&result[mpi.rank], 1, mpiType<T>(), result.data(), 1,
                  mpiType<T>(), mpi.communicator);
 
    return result;
}

References BaseLib::MPI::Mpi::communicator, mpiType(), BaseLib::MPI::Mpi::rank, and BaseLib::MPI::Mpi::size.

Referenced by allgatherv(), MeshLib::computeNumberOfRegularBaseNodesAtRank(), MeshLib::computeNumberOfRegularHigherOrderNodesAtRank(), MeshLib::computeRegularBaseNodeGlobalNodeIDsOfSubDomainPartition(), MeshLib::IO::getPartitionInfo(), and MeshLib::IO::NodePartitionedMeshReader::newMesh().

allgatherv()

template<typename T >

static std::vector< int > BaseLib::MPI::allgatherv ( std::span< T > const send_buffer, std::vector< std::remove_const_t< T > > & receive_buffer, Mpi const & mpi )

static

Allgather for variable data. Returns offsets in the receive buffer. The receive buffer is resized to accommodate the gathered data.

Definition at line 164 of file MPI.h.

{
    // Determine the number of elements to send
    int const size = static_cast<int>(send_buffer.size());
 
    // Gather sizes from all ranks
    std::vector<int> const sizes = allgather(size, mpi);
 
    // Compute offsets based on counts
    std::vector<int> const offsets = BaseLib::sizesToOffsets(sizes);
 
    // Resize receive buffer to hold all gathered data
    receive_buffer.resize(offsets.back());
 
    MPI_Allgatherv(send_buffer.data(), size, mpiType<T>(),
                   receive_buffer.data(), sizes.data(), offsets.data(),
                   mpiType<T>(), mpi.communicator);
 
    return offsets;
}

References allgather(), BaseLib::MPI::Mpi::communicator, mpiType(), and BaseLib::sizesToOffsets().

Referenced by MeshLib::computeGhostBaseNodeGlobalNodeIDsOfSubDomainPartition(), and MathLib::PETScVector::getGlobalVector().

allreduce() [1/2]

template<typename T >

static std::vector< T > BaseLib::MPI::allreduce ( std::vector< T > const & vector, MPI_Op const & mpi_op, Mpi const & mpi )

static

Definition at line 137 of file MPI.h.

{
    std::size_t const size = vector.size();
    std::vector<T> result(vector.size());
 
    MPI_Allreduce(vector.data(), result.data(), size, mpiType<T>(), mpi_op,
                  mpi.communicator);
    return result;
}

References BaseLib::MPI::Mpi::communicator, and mpiType().

allreduce() [2/2]

template<typename T >

static T BaseLib::MPI::allreduce ( T const & value, MPI_Op const & mpi_op, Mpi const & mpi )

static

Definition at line 128 of file MPI.h.

{
    T result{};
 
    MPI_Allreduce(&value, &result, 1, mpiType<T>(), mpi_op, mpi.communicator);
    return result;
}

References BaseLib::MPI::Mpi::communicator, and mpiType().

Referenced by MeshGeoToolsLib::BoundaryElementsAtPoint::BoundaryElementsAtPoint(), MeshLib::getNumberOfGlobalNodes(), NumLib::anonymous_namespace{DOFTableUtil.cpp}::norm1(), NumLib::anonymous_namespace{DOFTableUtil.cpp}::norm2(), NumLib::anonymous_namespace{DOFTableUtil.cpp}::normInfinity(), ProcessLib::PhaseField::PhaseFieldProcess< DisplacementDim >::postNonLinearSolverConcreteProcess(), ProcessLib::PhaseField::PhaseFieldProcess< DisplacementDim >::postTimestepConcreteProcess(), MeshLib::IO::NodePartitionedMeshReader::readProperties(), and reduceMin().

allreduceInplace()

template<typename T >

static void BaseLib::MPI::allreduceInplace ( std::vector< T > & vector, MPI_Op const & mpi_op, Mpi const & mpi )

static

Definition at line 149 of file MPI.h.

{
    MPI_Allreduce(MPI_IN_PLACE,
                  vector.data(),
                  vector.size(),
                  mpiType<T>(),
                  mpi_op,
                  mpi.communicator);
}

References BaseLib::MPI::Mpi::communicator, and mpiType().

Referenced by MeshLib::computeGhostBaseNodeGlobalNodeIDsOfSubDomainPartition().

mpiType()

template<typename T >

MPI_Datatype BaseLib::MPI::mpiType ( )

constexpr

Definition at line 66 of file MPI.h.

{
    using U = std::remove_const_t<T>;
    if constexpr (std::is_same_v<U, bool>)
    {
        return MPI_C_BOOL;
    }
    if constexpr (std::is_same_v<U, char>)
    {
        return MPI_CHAR;
    }
    if constexpr (std::is_same_v<U, double>)
    {
        return MPI_DOUBLE;
    }
    if constexpr (std::is_same_v<U, float>)
    {
        return MPI_FLOAT;
    }
    if constexpr (std::is_same_v<U, int>)
    {
        return MPI_INT;
    }
    if constexpr (std::is_same_v<U, std::size_t>)
    {
        return MPI_UNSIGNED_LONG;
    }
    if constexpr (std::is_same_v<U, unsigned int>)
    {
        return MPI_UNSIGNED;
    }
}

Referenced by allgather(), allgather(), allgatherv(), allreduce(), allreduce(), and allreduceInplace().

reduceMin()

static int BaseLib::MPI::reduceMin ( int const val )

inlinestatic

The reduction is implemented transparently for with and without MPI. In the latter case the input value is returned.

Definition at line 191 of file MPI.h.

{
#ifdef USE_PETSC
    return allreduce(val, MPI_MIN, Mpi{MPI_COMM_WORLD});
#else
    return val;
#endif
}

References allreduce().

Referenced by NumLib::NonlinearSolver< NonlinearSolverTag::Newton >::solve().