Topology¶

Located in file: MEL.hpp

void MEL::TopoCartesianMakeDims(const int numProcs, const int numdims, int *dims)¶

Compute the ‘ideal’ dimensions for a topolgy over n-processes.

See

MPI_Dims_create

Parameters

• numProcs -

  The number of processes in the topology

• numdims -

  The number of dimensions in the topology

• dims -

  Pointer to an (already allocated) array of length numdims

void MEL::TopoCartesianMakeDims(const Comm &comm, const int numdims, int *dims)¶

Compute the ‘ideal’ dimensions for a topolgy over n-processes.

Parameters

• comm -

  The comm object the topology should represent

• numdims -

  The number of dimensions in the topology

• dims -

  Pointer to an (already allocated) array of length numdims

std::vector<int> MEL::TopoCartesianMakeDims(const int numProcs, const int numdims)¶

Compute the ‘ideal’ dimensions for a topolgy over n-processes.

Return

Returns a std::vector of dimension sizes

Parameters

• numProcs -

  The number of processes in the topology

• numdims -

  The number of dimensions in the topology

std::vector<int> MEL::TopoCartesianMakeDims(const Comm &comm, const int numdims)¶

Compute the ‘ideal’ dimensions for a topolgy over n-processes.

Return

Returns a std::vector of dimension sizes

Parameters

• comm -

  The comm object the topology should represent

• numdims -

  The number of dimensions in the topology

Comm MEL::TopoCartesianCreate(const Comm &comm, int numdims, const int *dims, const int *periods)¶

Create a cartesian topology over a comm world.

See

MPI_Cart_create

Return

Returns a Comm world with an attached topology

Parameters

• comm -

  The comm object the topology should represent

• numdims -

  The number of dimensions in the topology

• dims -

  Pointer to an array of sizes of each dimension

• periods -

  Pointer to an array of logicals representing if each dimension is periodic or not

Comm MEL::TopoCartesianCreate(const Comm &comm, const std::vector<TopoCartesian_Dim> &dims)¶

Create a cartesian topology over a comm world.

Return

Returns a Comm world with an attached topology

Parameters

• comm -

  The comm object the topology should represent

• dims -

  A std::vector of pairs representing dimension sizes and whether dimensions are periodic

int MEL::TopoCartesianNumDims(const Comm &comm)¶

Get the number of dimensions in an attached cartesian topology of a comm world.

See

MPI_Cartdim_get

Return

Returns the number of dimensions in the attached cartesian topology

Parameters

• comm -

  The comm object the topology is attached to

int MEL::TopoCartesianRank(const Comm &comm, const int *coords)¶

Get the rank within the attached cartesian topology of a comm world.

See

MPI_Cart_rank

Return

Returns the rank in the attached cartesian topology

Parameters

• comm -

  The comm object the topology is attached to

• coords -

  Pointer to an array representing the n-dim coordinates in the topology

int MEL::TopoCartesianRank(const Comm &comm, const std::vector<int> coords)¶

Get the rank within the attached cartesian topology of a comm world.

Return

Returns the rank in the attached cartesian topology

Parameters

• comm -

  The comm object the topology is attached to

• coords -

  A std::vector representing the n-dim coordinates in the topology

void MEL::TopoCartesianCoords(const Comm &comm, const int rank, int numdims, int *coords)¶

Get the n-dim coordinates within the attached cartesian topology of a comm world.

See

MPI_Cart_coords

Parameters

• comm -

  The comm object the topology is attached to

• rank -

  The rank within comm

• numdims -

  The number of dimensions in the topology

• coords -

  Pointer to an array of numdims ints representing the coordinates

std::vector<int> MEL::TopoCartesianCoords(const Comm &comm, const int rank, int numdims)¶

Get the n-dim coordinates within the attached cartesian topology of a comm world.

Return

Returns a std::vector representing the n-dim coordinates

Parameters

• comm -

  The comm object the topology is attached to

• rank -

  The rank within comm

• numdims -

  The number of dimensions in the topology

std::vector<int> MEL::TopoCartesianCoords(const Comm &comm, const int rank)¶

Get the n-dim coordinates within the attached cartesian topology of a comm world.

Return

Returns a std::vector representing the n-dim coordinates

Parameters

• comm -

  The comm object the topology is attached to

• rank -

  The rank within comm

std::vector<int> MEL::TopoCartesianCoords(const Comm &comm)¶

Get the n-dim coordinates within the attached cartesian topology of a comm world.

Return

Returns a std::vector representing the n-dim coordinates

Parameters

• comm -

  The comm object the topology is attached to

void MEL::TopoCartesianGet(const Comm &comm, int numdims, int *dims, int *periods, int *coords)¶

Get the properties of an attached cartesian topology of a comm world.

See

MPI_Cart_get

Parameters

• comm -

  The comm object the topology is attached to

• numdims -

  The number of dimensions in the topology

• dims -

  Pointer to an array of n-dims size representing the sizes of each dimension

• periods -

  Pointer to an array of n-dims size representing whether each dimension is periodic

• coords -

  Pointer to an array of n-dims size representing the coordinate in each dimension

std::pair<std::vector<int>, std::vector<TopoCartesian_Dim>> MEL::TopoCartesianGet(const Comm &comm)¶

Get the properties of an attached cartesian topology of a comm world.

Return

Returns a std::pair of a std::vector representing the process coordinates, and a std::vector of pairs representing the dimension sizes and periods

Parameters

• comm -

  The comm object the topology is attached to

void MEL::TopoCartesianShift(const Comm &comm, int direction, int disp, int &rank_prev, int &rank_next)¶

Compute the ranks of a left and right shifted neighbor for a given dimension within a topology.

See

MPI_Cart_shift

Parameters

• comm -

  The comm object the topology is attached to

• direction -

  The dimension to shift in

• disp -

  How much to shift by

• rank_prev -

  The left neighbour

• rank_next -

  The right neighbour

std::pair<int, int> MEL::TopoCartesianShift(const Comm &comm, int direction, int disp)¶

Compute the ranks of a left and right shifted neighbor for a given dimension within a topology.

Return

Returns a std::pair representing the ranks of the left and right neighbour

Parameters

• comm -

  The comm object the topology is attached to

• direction -

  The dimension to shift in

• disp -

  How much to shift by

CartesianStencil2D5P MEL::TopoCartesianStencil2D5P(const Comm &comm)¶

Create a 2D 5-point stencil of ranks representing the neighbouring processes.

Return

Returns a 2D 5-point stencil of comm ranks

Parameters

• comm -

  The comm object the topology is attached to

CartesianStencil2D9P MEL::TopoCartesianStencil2D9P(const Comm &comm)¶

Create a 2D 9-point stencil of ranks representing the neighbouring processes.

Return

Returns a 2D 9-point stencil of comm ranks

Parameters

• comm -

  The comm object the topology is attached to