PetscBuildTwoSidedType#

algorithm for setting up two-sided communication for use with PetscSF

Synopsis#

typedef enum {
  PETSC_BUILDTWOSIDED_NOTSET     = -1,
  PETSC_BUILDTWOSIDED_ALLREDUCE  = 0,
  PETSC_BUILDTWOSIDED_IBARRIER   = 1,
  PETSC_BUILDTWOSIDED_REDSCATTER = 2
  /* Updates here must be accompanied by updates in finclude/petscsys.h and the string array in mpits.c */
} PetscBuildTwoSidedType;

Values#

  • PETSC_BUILDTWOSIDED_ALLREDUCE - classical algorithm using an MPI_Allreduce() with a buffer of length equal to the communicator size. Not memory-scalable due to the large reduction size. Requires only an MPI-1 implementation.

  • PETSC_BUILDTWOSIDED_IBARRIER - nonblocking algorithm based on MPI_Issend() and MPI_Ibarrier(). Proved communication-optimal in Hoefler, Siebert, and Lumsdaine (2010). Requires an MPI-3 implementation.

  • PETSC_BUILDTWOSIDED_REDSCATTER - similar to above, but use more optimized function that only communicates the part of the reduction that is necessary. Requires an MPI-2 implementation.

See Also#

PetscCommBuildTwoSided(), PetscCommBuildTwoSidedSetType(), PetscCommBuildTwoSidedGetType()

Level#

developer

Location#

include/petscsystypes.h

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