dolfinx::MPI Class Reference

This class provides utility functions for easy communication with MPI and handles cases when DOLFINx is not configured with MPI. More...

#include <MPI.h>

Classes
class	Comm
	A duplicate MPI communicator and manage lifetime of the communicator. More...
struct	dependent_false

Static Public Member Functions
static int	rank (MPI_Comm comm)
	Return process rank for the communicator.
static int	size (MPI_Comm comm)
	Return size of the group (number of processes) associated with the communicator.
template<typename T >
static graph::AdjacencyList< T >	all_to_all (MPI_Comm comm, const graph::AdjacencyList< T > &send_data)
	Send in_values[p0] to process p0 and receive values from process p1 in out_values[p1].
static std::vector< int >	compute_graph_edges (MPI_Comm comm, const std::set< int > &edges)
template<typename T >
static graph::AdjacencyList< T >	neighbor_all_to_all (MPI_Comm neighbor_comm, const graph::AdjacencyList< T > &send_data)
	Neighborhood all-to-all. Send data to neighbors. Send in_values[n0] to neighbor process n0 and receive values from neighbor process n1 in out_values[n1].
static std::tuple< std::vector< int >, std::vector< int > >	neighbors (MPI_Comm neighbor_comm)
static std::size_t	global_offset (MPI_Comm comm, std::size_t range, bool exclusive)
	Find global offset (index) (wrapper for MPI_(Ex)Scan with MPI_SUM as reduction op)
static std::array< std::int64_t, 2 >	local_range (int process, std::int64_t N, int size)
	Return local range for given process, splitting [0, N - 1] into size() portions of almost equal size.
static int	index_owner (int size, std::size_t index, std::size_t N)
	Return which process owns index (inverse of local_range) More...
template<typename T >
static MPI_Datatype	mpi_type ()
	MPI Type.

Detailed Description

This class provides utility functions for easy communication with MPI and handles cases when DOLFINx is not configured with MPI.

Member Function Documentation

compute_graph_edges()

std::vector< int > dolfinx::MPI::compute_graph_edges ( MPI_Comm  comm, const std::set< int > &  edges  )

static

Todo:

Experimental. Maybe be moved or removed.

Compute communication graph edges. The caller provides edges that it can define, and will receive edges to it that are defined by other ranks.

Note

This function involves global communication

Parameters

[in]	comm	The MPI communicator
[in]	edges	Communication edges between the caller and the ranks in edges.

Returns

Ranks that have defined edges from them to this rank

index_owner()

int dolfinx::MPI::index_owner ( int  size, std::size_t  index, std::size_t  N  )

static

Return which process owns index (inverse of local_range)

Parameters

[in]	size	Number of MPI ranks
[in]	index	The index to determine owning rank
[in]	N	Total number of indices

Returns

The rank of the owning process

neighbors()

std::tuple< std::vector< int >, std::vector< int > > dolfinx::MPI::neighbors ( MPI_Comm  neighbor_comm )

static

Todo:

Clarify directions

Return list of neighbors for a neighborhood communicator

Parameters

[in]

neighbor_comm

Neighborhood communicator

Returns

source ranks, destination ranks

---

The documentation for this class was generated from the following files:

• /__w/dolfinx/dolfinx/cpp/dolfinx/common/MPI.h
• /__w/dolfinx/dolfinx/cpp/dolfinx/common/MPI.cpp