.. Documentation for the header file dolfin/common/MPI.h
.. _programmers_reference_cpp_common_mpi:
MPI.h
=====
.. note::
The documentation on this page was automatically extracted from the
DOLFIN C++ code and may need to be edited or expanded.
.. cpp:class:: MPIInfo
.. cpp:class:: MPI
This class provides utility functions for easy communication
with MPI and handles cases when DOLFIN is not configured with
MPI.
.. cpp:class:: Comm
.. cpp:function:: Comm(MPI_Comm comm)
Duplicate communicator and wrap duplicate
.. cpp:function:: void free()
Free (destroy) communicator. Calls function 'MPI_Comm_free'.
.. cpp:function:: void reset(MPI_Comm comm)
Duplicate communivator, and free any previously created
communicator
.. cpp:function:: unsigned int rank() const
Return process rank for the communicator
.. cpp:function:: unsigned int size() const
Return size of the group (number of processes) associated
with the communicator. This function will also intialise MPI
if it hasn't already been intialised.
.. cpp:function:: void barrier() const
Set a barrier (synchronization point)
.. cpp:function:: MPI_Comm comm() const
Return the underlying MPI_Comm object
.. cpp:function:: static unsigned int rank(MPI_Comm comm)
Return process rank for the communicator
.. cpp:function:: static unsigned int size(MPI_Comm comm)
Return size of the group (number of processes) associated with
the communicator
.. cpp:function:: static bool is_broadcaster(MPI_Comm comm)
Determine whether we should broadcast (based on current
parallel policy)
.. cpp:function:: static bool is_receiver(MPI_Comm comm)
Determine whether we should receive (based on current parallel
policy)
.. cpp:function:: static void barrier(MPI_Comm comm)
Set a barrier (synchronization point)
.. cpp:function:: static void all_to_all(MPI_Comm comm, std::vector<std::vector<T>>& in_values, std::vector<std::vector<T>>& out_values)
Send in_values[p0] to process p0 and receive values from
process p1 in out_values[p1]
.. cpp:function:: static void all_to_all(MPI_Comm comm, std::vector<std::vector<T>>& in_values, std::vector<T>& out_values)
Send in_values[p0] to process p0 and receive values from
all processes in out_values
.. cpp:function:: static void broadcast(MPI_Comm comm, std::vector<T>& value, unsigned int broadcaster=0)
Broadcast vector of value from broadcaster to all processes
.. cpp:function:: static void broadcast(MPI_Comm comm, T& value, unsigned int broadcaster=0)
Broadcast single primitive from broadcaster to all processes
.. cpp:function:: static void scatter(MPI_Comm comm, const std::vector<std::vector<T>>& in_values, std::vector<T>& out_value, unsigned int sending_process=0)
Scatter vector in_values[i] to process i
.. cpp:function:: static void scatter(MPI_Comm comm, const std::vector<T>& in_values, T& out_value, unsigned int sending_process=0)
Scatter primitive in_values[i] to process i
.. cpp:function:: static void gather(MPI_Comm comm, const std::vector<T>& in_values, std::vector<T>& out_values, unsigned int receiving_process=0)
Gather values on one process
.. cpp:function:: static void gather(MPI_Comm comm, const std::string& in_values, std::vector<std::string>& out_values, unsigned int receiving_process=0)
Gather strings on one process
.. cpp:function:: static void all_gather(MPI_Comm comm, const std::vector<T>& in_values, std::vector<T>& out_values)
Gather values from all processes. Same data count from each
process (wrapper for MPI_Allgather)
.. cpp:function:: static void all_gather(MPI_Comm comm, const std::vector<T>& in_values, std::vector<std::vector<T>>& out_values)
Gather values from each process (variable count per process)
.. cpp:function:: static void all_gather(MPI_Comm comm, const T in_value, std::vector<T>& out_values)
Gather values, one primitive from each process (MPI_Allgather)
.. cpp:function:: static void all_gather(MPI_Comm comm, const std::string& in_values, std::vector<std::string>& out_values)
Gather values, one primitive from each process (MPI_Allgather).
Specialization for std::string
.. cpp:function:: static T max(MPI_Comm comm, const T& value)
Return global max value
.. cpp:function:: static T min(MPI_Comm comm, const T& value)
Return global min value
.. cpp:function:: static T sum(MPI_Comm comm, const T& value)
Sum values and return sum
.. cpp:function:: static T avg(MPI_Comm comm, const T& value)
Return average across comm; implemented only for T == Table
.. cpp:function:: static T all_reduce(MPI_Comm comm, const T& value, X op)
All reduce
.. cpp:function:: 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)
.. cpp:function:: static void send_recv(MPI_Comm comm, const std::vector<T>& send_value, unsigned int dest, int send_tag, std::vector<T>& recv_value, unsigned int source, int recv_tag)
Send-receive data between processes (blocking)
.. cpp:function:: static void send_recv(MPI_Comm comm, const std::vector<T>& send_value, unsigned int dest, std::vector<T>& recv_value, unsigned int source)
Send-receive data between processes
.. cpp:function:: static std::pair<std::int64_t, std::int64_t> local_range(MPI_Comm comm, std::int64_t N)
Return local range for local process, splitting [0, N - 1] into
size() portions of almost equal size
.. cpp:function:: static std::pair<std::int64_t, std::int64_t> local_range(MPI_Comm comm, int process, std::int64_t N)
Return local range for given process, splitting [0, N - 1] into
size() portions of almost equal size
.. cpp:function:: static std::pair<std::int64_t, std::int64_t> compute_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
.. cpp:function:: static unsigned int index_owner(MPI_Comm comm, std::size_t index, std::size_t N)
Return which process owns index (inverse of local_range)
.. cpp:function:: static MPI_Op MPI_AVG()
Return average reduction operation; recognized by
all_reduce(MPI_Comm, Table&, MPI_Op)