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Diffstat (limited to 'src/H5FDmpio.h')
| -rw-r--r-- | src/H5FDmpio.h | 225 |
1 files changed, 224 insertions, 1 deletions
diff --git a/src/H5FDmpio.h b/src/H5FDmpio.h index 79b52c7..8caf11c 100644 --- a/src/H5FDmpio.h +++ b/src/H5FDmpio.h @@ -44,14 +44,237 @@ H5_DLLVAR hbool_t H5FD_mpi_opt_types_g; #ifdef __cplusplus extern "C" { #endif -H5_DLL hid_t H5FD_mpio_init(void); +H5_DLL hid_t H5FD_mpio_init(void); + +/** + * \ingroup FAPL + * + * \brief Stores MPI IO communicator information to the file access property list + * + * \fapl_id + * \param[in] comm MPI-2 communicator + * \param[in] info MPI-2 info object + * \returns \herr_t + * + * \details H5Pset_fapl_mpio() stores the user-supplied MPI IO parameters \p + * comm, for communicator, and \p info, for information, in the file + * access property list \p fapl_id. That property list can then be used + * to create and/or open a file. + * + * H5Pset_fapl_mpio() is available only in the parallel HDF5 library + * and is not a collective function. + * + * \p comm is the MPI communicator to be used for file open, as defined + * in \c MPI_File_open of MPI-2. This function makes a duplicate of the + * communicator, so modifications to \p comm after this function call + * returns have no effect on the file access property list. + * + * \p info is the MPI Info object to be used for file open, as defined + * in MPI_File_open() of MPI-2. This function makes a duplicate copy of + * the Info object, so modifications to the Info object after this + * function call returns will have no effect on the file access + * property list. + * + * If the file access property list already contains previously-set + * communicator and Info values, those values will be replaced and the + * old communicator and Info object will be freed. + * + * \note Raw dataset chunk caching is not currently supported when using this + * file driver in read/write mode. All calls to H5Dread() and H5Dwrite() + * will access the disk directly, and H5Pset_cache() and + * H5Pset_chunk_cache() will have no effect on performance.\n + * Raw dataset chunk caching is supported when this driver is used in + * read-only mode. + * + * \version 1.4.5 Handling of the MPI Communicator and Info object changed at + * this release. A duplicate of each of these is now stored in the property + * list instead of pointers to each. + * \since 1.4.0 + * + */ H5_DLL herr_t H5Pset_fapl_mpio(hid_t fapl_id, MPI_Comm comm, MPI_Info info); + +/** + * \ingroup FAPL + * + * \brief Returns MPI IO communicator information + * + * \fapl_id + * \param[out] comm MPI-2 communicator + * \param[out] info MPI-2 info object + * \returns \herr_t + * + * \details If the file access property list is set to the #H5FD_MPIO driver, + * H5Pget_fapl_mpio() returns duplicates of the stored MPI communicator + * and Info object through the \p comm and \p info pointers, if those + * values are non-null. + * + * Since the MPI communicator and Info object are duplicates of the + * stored information, future modifications to the access property list + * will not affect them. It is the responsibility of the application to + * free these objects. + * + * \version 1.4.5 Handling of the MPI Communicator and Info object changed at + * this release. A duplicate of each of these is now stored in the + * property list instead of pointers to each. + * \since 1.4.0 + * + */ H5_DLL herr_t H5Pget_fapl_mpio(hid_t fapl_id, MPI_Comm *comm /*out*/, MPI_Info *info /*out*/); + +/** + * \ingroup DXPL + * + * \brief Sets data transfer mode + * + * \dxpl_id + * \param[in] xfer_mode Transfer mode + * \returns \herr_t + * + * \details H5Pset_dxpl_mpio() sets the data transfer property list \p dxpl_id + * to use transfer mode \p xfer_mode. The property list can then be + * used to control the I/O transfer mode during data I/O operations. + * + * Valid transfer modes are #H5FD_MPIO_INDEPENDENT (default) and + * #H5FD_MPIO_COLLECTIVE. + * + * \since 1.4.0 + * + */ H5_DLL herr_t H5Pset_dxpl_mpio(hid_t dxpl_id, H5FD_mpio_xfer_t xfer_mode); + +/** + * \ingroup DXPL + * + * \brief Returns the data transfer mode + * + * \dxpl_id + * \param[out] xfer_mode Transfer mode + * \returns \herr_t + * + * \details H5Pget_dxpl_mpio() queries the data transfer mode currently set in + * the data transfer property list \p dxpl_id. + * + * Upon return, \p xfer_mode contains the data transfer mode, if it is + * non-null. + * + * H5Pget_dxpl_mpio() is not a collective function. + * + * \since 1.4.0 + * + */ H5_DLL herr_t H5Pget_dxpl_mpio(hid_t dxpl_id, H5FD_mpio_xfer_t *xfer_mode /*out*/); + +/** + * \ingroup DXPL + * + * \brief Sets data transfer mode + * + * \dxpl_id + * \param[in] opt_mode Transfer mode + * \returns \herr_t + * + * \details H5Pset_dxpl_mpio() sets the data transfer property list \p dxpl_id + * to use transfer mode xfer_mode. The property list can then be used + * to control the I/O transfer mode during data I/O operations. + * + * Valid transfer modes are #H5FD_MPIO_INDEPENDENT (default) and + * #H5FD_MPIO_COLLECTIVE. + * + * \since 1.4.0 + * + */ H5_DLL herr_t H5Pset_dxpl_mpio_collective_opt(hid_t dxpl_id, H5FD_mpio_collective_opt_t opt_mode); + +/** + * \ingroup DXPL + * + * \brief Sets a flag specifying linked-chunk I/O or multi-chunk I/O + * + * \dxpl_id + * \param[in] opt_mode Transfer mode + * \returns \herr_t + * + * \details H5Pset_dxpl_mpio_chunk_opt() specifies whether I/O is to be + * performed as linked-chunk I/O or as multi-chunk I/O. This function + * overrides the HDF5 library's internal algorithm for determining + * which mechanism to use. + * + * When an application uses collective I/O with chunked storage, the + * HDF5 library normally uses an internal algorithm to determine + * whether that I/O activity should be conducted as one linked-chunk + * I/O or as multi-chunk I/O. H5Pset_dxpl_mpio_chunk_opt() is provided + * so that an application can override the library's algorithm in + * circumstances where the library might lack the information needed to + * make an optimal decision. + * + * H5Pset_dxpl_mpio_chunk_opt() works by setting one of the following + * flags in the parameter \p opt_mode: + * - #H5FD_MPIO_CHUNK_ONE_IO - Do one-link chunked I/O + * - #H5FD_MPIO_CHUNK_MULTI_IO - Do multi-chunked I/O + * + * This function works by setting a corresponding property in the + * dataset transfer property list \p dxpl_id. + * + * The library performs I/O in the specified manner unless it + * determines that the low-level MPI IO package does not support the + * requested behavior; in such cases, the HDF5 library will internally + * use independent I/O. + * + * Use of this function is optional. + * + * \todo Add missing version information + * + */ H5_DLL herr_t H5Pset_dxpl_mpio_chunk_opt(hid_t dxpl_id, H5FD_mpio_chunk_opt_t opt_mode); + +/** + * \ingroup DXPL + * + * \brief Sets a numeric threshold for linked-chunk I/O + * + * \dxpl_id + * \param[in] num_chunk_per_proc + * \returns \herr_t + * + * \details H5Pset_dxpl_mpio_chunk_opt_num() sets a numeric threshold for the + * use of linked-chunk I/O. + * + * The library will calculate the average number of chunks selected by + * each process when doing collective access with chunked storage. If + * the number is greater than the threshold set in \p + * num_chunk_per_proc, the library will use linked-chunk I/O; + * otherwise, a separate I/O process will be invoked for each chunk + * (multi-chunk I/O). + * + * \todo Add missing version information + * + */ H5_DLL herr_t H5Pset_dxpl_mpio_chunk_opt_num(hid_t dxpl_id, unsigned num_chunk_per_proc); + +/** + * \ingroup DXPL + * + * \brief Sets a ratio threshold for collective I/O + * + * \dxpl_id + * \param[in] percent_num_proc_per_chunk + * \returns \herr_t + * + * \details H5Pset_dxpl_mpio_chunk_opt_ratio() sets a threshold for the use of + * collective I/O based on the ratio of processes with collective + * access to a dataset with chunked storage. The decision whether to + * use collective I/O is made on a per-chunk basis. + * + * The library will calculate the percentage of the total number of + * processes, the ratio, that hold selections in each chunk. If that + * percentage is greater than the threshold set in \p + * percent_proc_per_chunk, the library will do collective I/O for this + * chunk; otherwise, independent I/O will be done for the chunk. + * + * \todo Add missing version information + * + */ H5_DLL herr_t H5Pset_dxpl_mpio_chunk_opt_ratio(hid_t dxpl_id, unsigned percent_num_proc_per_chunk); #ifdef __cplusplus } |