PetscSubcomm#

A decomposition of an MPI communicator into subcommunicators

Synopsis#

typedef struct _n_PetscSubcomm *PetscSubcomm;

Values#

PETSC_SUBCOMM_GENERAL - similar to MPI_Comm_split() each process sets the new communicator (color) they will belong to and the order within that communicator
PETSC_SUBCOMM_CONTIGUOUS - each new communicator contains a set of process with contiguous ranks in the original MPI communicator
PETSC_SUBCOMM_INTERLACED - each new communictor contains a set of processes equally far apart in rank from the others in that new communicator

Sample Usage#

       PetscSubcommCreate()
       PetscSubcommSetNumber()
       PetscSubcommSetType(PETSC_SUBCOMM_INTERLACED);
       ccomm = PetscSubcommChild()
       PetscSubcommDestroy()

Example#

Consider a communicator with six processes split into 3 subcommunicators.

   PETSC_SUBCOMM_CONTIGUOUS - the first communicator contains rank 0,1  the second rank 2,3 and the third rank 4,5 in the original ordering of the original communicator
   PETSC_SUBCOMM_INTERLACED - the first communicator contains rank 0,3, the second 1,4 and the third 2,5

Note#

After a call to PetscSubcommSetType(), PetscSubcommSetTypeGeneral(), or PetscSubcommSetFromOptions() one may call

     PetscSubcommChild() returns the associated subcommunicator on this process
     PetscSubcommContiguousParent() returns a parent communitor but with all child of the same subcommunicator having contiguous rank

Developer Note#

This is used in objects such as PCREDUNDANT to manage the subcommunicators on which the redundant computations are performed.

Level#

advanced

Location#

include/petscsystypes.h

Examples#

src/ksp/ksp/tutorials/ex73.c

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Index of all manual pages