petsc-3.4.2 2013-07-02

# PetscBuildTwoSidedType

algorithm for setting up two-sided communication

### Synopsis

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

     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 MPI-1.

     PETSC_BUILDTWOSIDED_IBARRIER - nonblocking algorithm based on MPI_Issend and MPI_Ibarrier.

         Proved communication-optimal in Hoefler, Siebert, and Lumsdaine (2010). Requires MPI-3.

### See Also

PetscCommBuildTwoSided(), PetscCommBuildTwoSidedSetType(), PetscCommBuildTwoSidedGetType()

Level:developer
Location: include/petscsys.h
Index of all Sys routines
Table of Contents for all manual pages
Index of all manual pages