Ubuntu Manpage: MPI_Comm_split_type - Creates new communicators based on colors and keys.

NAME

       MPI_Comm_split_type  - Creates new communicators based on colors and keys.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Comm_split_type(MPI_Comm comm, int split_type, int key,
            MPI_Info info, MPI_Comm *newcomm)

Fortran Syntax

       INCLUDE 'mpif.h'
       MPI_COMM_SPLIT_TYPE(COMM, SPLIT_TYPE, KEY, INFO, NEWCOMM, IERROR)
            INTEGER   COMM, SPLIT_TYPE, KEY, INFO, NEWCOMM, IERROR

INPUT PARAMETERS

       comm      Communicator (handle).

       split_type
                 Type of processes to be grouped together (integer).

       key       Control of rank assignment (integer).

       info      Info argument (handle).

OUTPUT PARAMETERS

       newcomm   New communicator (handle).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       This  function  partitions  the  group  associated  with  comm into disjoint subgroups, based on the type
       specied by split_type. Each subgroup contains all processes of the same type.  Within each subgroup,  the
       processes are ranked in the order defined by the value of the argument key, with ties broken according to
       their rank in the old group. A new communicator is created for each subgroup  and  returned  in  newcomm.
       This  is a collective call; all processes must provide the same split_type, but each process is permitted
       to provide different values for key. An exception to this rule is that a  process  may  supply  the  type
       value MPI_UNDEFINED, in which case newcomm returns MPI_COMM_NULL.

SPLIT TYPES

MPI_COMM_TYPE_SHARED
This type splits the communicator into subcommunicators, each of which can create a shared
memory region.

OMPI_COMM_TYPE_NODE
Synonym for MPI_COMM_TYPE_SHARED.

OMPI_COMM_TYPE_HWTHREAD
This type splits the communicator into subcommunicators, each of which belongs to the same
hardware thread.

OMPI_COMM_TYPE_CORE
This type splits the communicator into subcommunicators, each of which belongs to the same
core/processing unit.

OMPI_COMM_TYPE_L1CACHE
This type splits the communicator into subcommunicators, each of which belongs to the same L1
cache.

OMPI_COMM_TYPE_L2CACHE
This type splits the communicator into subcommunicators, each of which belongs to the same L2
cache.

OMPI_COMM_TYPE_L3CACHE
This type splits the communicator into subcommunicators, each of which belongs to the same L3
cache.

OMPI_COMM_TYPE_SOCKET
This type splits the communicator into subcommunicators, each of which belongs to the same
socket.

OMPI_COMM_TYPE_NUMA
This type splits the communicator into subcommunicators, each of which belongs to the same
NUMA-node.

OMPI_COMM_TYPE_BOARD
This type splits the communicator into subcommunicators, each of which belongs to the same
board.

OMPI_COMM_TYPE_HOST
This type splits the communicator into subcommunicators, each of which belongs to the same
host.

OMPI_COMM_TYPE_CU
This type splits the communicator into subcommunicators, each of which belongs to the same
computational unit.

OMPI_COMM_TYPE_CLUSTER
This type splits the communicator into subcommunicators, each of which belongs to the same
cluster.

NOTES

       The  communicator  keys  denoted with an OMPI_ prefix instead of an MPI_ prefix are specific to Open MPI,
       and are not part of the MPI standard.  Their use should be  protected  by  the  OPEN_MPI  C  preprocessor
       macro.

ERRORS

       Almost  all  MPI  routines  return  an  error  value; C routines as the value of the function and Fortran
       routines in the last argument.

       Before the error value is returned, the current MPI error handler  is  called.  By  default,  this  error
       handler  aborts  the  MPI  job,  except  for  I/O  function errors. The error handler may be changed with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values
       to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.