PetscSFReduceBegin#
begin reduction of leafdata into rootdata, to be completed with call to PetscSFReduceEnd()
Synopsis#
#include "petscsf.h"
PetscErrorCode PetscSFReduceBegin(PetscSF sf, MPI_Datatype unit, const void *leafdata, void *rootdata, MPI_Op op)
Collective
Input Parameters#
sf - star forest
unit - data type
leafdata - values to reduce
op - reduction operation
Output Parameter#
rootdata - result of reduction of values from all leaves of each root
Note#
When PETSc is configured with device support, it will use its own mechanism to figure out whether the given data pointers
are host pointers or device pointers, which may incur a noticeable cost. If you already knew the info, you should
use PetscSFReduceWithMemTypeBegin() instead.
See Also#
PetscSF, PetscSFBcastBegin(), PetscSFReduceWithMemTypeBegin(), PetscSFReduceEnd()
Level#
intermediate
Location#
Examples#
src/vec/is/sf/tutorials/ex1.c
src/vec/is/sf/tutorials/ex1f.F90
Implementations#
PetscSFReduceBegin_Allgather in src/vec/is/sf/impls/basic/allgather/sfallgather.c
PetscSFReduceBegin_Allgatherv in src/vec/is/sf/impls/basic/allgatherv/sfallgatherv.c
PetscSFReduceBegin_Alltoall in src/vec/is/sf/impls/basic/alltoall/sfalltoall.c
PetscSFReduceBegin_Gather in src/vec/is/sf/impls/basic/gather/sfgather.c
PetscSFReduceBegin_Gatherv in src/vec/is/sf/impls/basic/gatherv/sfgatherv.c
PetscSFReduceBegin_Neighbor in src/vec/is/sf/impls/basic/neighbor/sfneighbor.c
PetscSFReduceBegin_Basic in src/vec/is/sf/impls/basic/sfbasic.c
PetscSFReduceBegin_Window in src/vec/is/sf/impls/window/sfwindow.c
Index of all PetscSF routines
Table of Contents for all manual pages
Index of all manual pages