PetscViewerHDF5SetCollective#
Use collective MPI-IO transfer mode for HDF5 reads and writes.
Synopsis#
#include "petscviewerhdf5.h" 
PetscErrorCode PetscViewerHDF5SetCollective(PetscViewer viewer, PetscBool flg)
Logically Collective; flg must contain common value
Input Parameters#
- viewer - the - PetscViewer; if it is not- PETSCVIEWERHDF5then this command is ignored
- flg - - PETSC_TRUEfor collective mode;- PETSC_FALSEfor independent mode (default)
Options Database Key#
- -viewer_hdf5_collective - turns on (true) or off (false) collective transfers 
Note#
Collective mode gives the MPI-IO layer underneath HDF5 a chance to do some additional collective optimizations and hence can perform better. However, this works correctly only since HDF5 1.10.3 and if HDF5 is installed for MPI; hence, we ignore this setting for older versions.
Developer Notes#
In the HDF5 layer, PETSC_TRUE / PETSC_FALSE means H5Pset_dxpl_mpio() is called with H5FD_MPIO_COLLECTIVE / H5FD_MPIO_INDEPENDENT, respectively.
This in turn means use of MPI_File_{read,write}all /  MPI_File{read,write} in the MPI-IO layer, respectively.
See HDF5 documentation and MPI-IO documentation for details.
See Also#
Viewers: Looking at PETSc Objects, PETSCVIEWERHDF5, PetscViewerHDF5GetCollective(), PetscViewerCreate(), PetscViewerSetType(), PetscViewerHDF5Open()
Level#
intermediate
Location#
Implementations#
PetscViewerHDF5SetCollective_HDF5() in src/sys/classes/viewer/impls/hdf5/hdf5v.c
Index of all Viewer routines
Table of Contents for all manual pages
Index of all manual pages