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Diffstat (limited to 'HDF5Examples/C/H5PAR/ph5_filtered_writes.c')
| -rw-r--r-- | HDF5Examples/C/H5PAR/ph5_filtered_writes.c | 488 |
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diff --git a/HDF5Examples/C/H5PAR/ph5_filtered_writes.c b/HDF5Examples/C/H5PAR/ph5_filtered_writes.c new file mode 100644 index 0000000..104704a --- /dev/null +++ b/HDF5Examples/C/H5PAR/ph5_filtered_writes.c @@ -0,0 +1,488 @@ +/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * + * Copyright by The HDF Group. * + * All rights reserved. * + * * + * This file is part of HDF5. The full HDF5 copyright notice, including * + * terms governing use, modification, and redistribution, is contained in * + * the COPYING file, which can be found at the root of the source code * + * distribution tree, or in https://www.hdfgroup.org/licenses. * + * If you do not have access to either file, you may request a copy from * + * help@hdfgroup.org. * + * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ + +/* + * Example of using the parallel HDF5 library to write to datasets + * with filters applied to them. + * + * If the HDF5_NOCLEANUP environment variable is set, the file that + * this example creates will not be removed as the example finishes. + * + * The need of requirement of parallel file prefix is that in general + * the current working directory in which compiling is done, is not suitable + * for parallel I/O and there is no standard pathname for parallel file + * systems. In some cases, the parallel file name may even need some + * parallel file type prefix such as: "pfs:/GF/...". Therefore, this + * example parses the HDF5_PARAPREFIX environment variable for a prefix, + * if one is needed. + */ + +#include <stdlib.h> + +#include "hdf5.h" + +#if defined(H5_HAVE_PARALLEL) && defined(H5_HAVE_PARALLEL_FILTERED_WRITES) + +#define EXAMPLE_FILE "ph5_filtered_writes.h5" +#define EXAMPLE_DSET1_NAME "DSET1" +#define EXAMPLE_DSET2_NAME "DSET2" + +#define EXAMPLE_DSET_DIMS 2 +#define EXAMPLE_DSET_CHUNK_DIM_SIZE 10 + +/* Dataset datatype */ +#define HDF5_DATATYPE H5T_NATIVE_INT +typedef int C_DATATYPE; + +#ifndef PATH_MAX +#define PATH_MAX 512 +#endif + +/* Global variables */ +int mpi_rank, mpi_size; + +/* + * Routine to set an HDF5 filter on the given DCPL + */ +static void +set_filter(hid_t dcpl_id) +{ + htri_t filter_avail; + + /* + * Check if 'deflate' filter is available + */ + filter_avail = H5Zfilter_avail(H5Z_FILTER_DEFLATE); + if (filter_avail < 0) + return; + else if (filter_avail) { + /* + * Set 'deflate' filter with reasonable + * compression level on DCPL + */ + H5Pset_deflate(dcpl_id, 6); + } + else { + /* + * Set Fletcher32 checksum filter on DCPL + * since it is always available in HDF5 + */ + H5Pset_fletcher32(dcpl_id); + } +} + +/* + * Routine to fill a data buffer with data. Assumes + * dimension rank is 2 and data is stored contiguous. + */ +void +fill_databuf(hsize_t start[], hsize_t count[], hsize_t stride[], C_DATATYPE *data) +{ + C_DATATYPE *dataptr = data; + hsize_t i, j; + + /* Use MPI rank value for data */ + for (i = 0; i < count[0]; i++) { + for (j = 0; j < count[1]; j++) { + *dataptr++ = mpi_rank; + } + } +} + +/* Cleanup created file */ +static void +cleanup(char *filename) +{ + hbool_t do_cleanup = getenv(HDF5_NOCLEANUP) ? 0 : 1; + + if (do_cleanup) + MPI_File_delete(filename, MPI_INFO_NULL); +} + +/* + * Routine to write to a dataset in a fashion + * where no chunks in the dataset are written + * to by more than 1 MPI rank. This will + * generally give the best performance as the + * MPI ranks will need the least amount of + * inter-process communication. + */ +static void +write_dataset_no_overlap(hid_t file_id, hid_t dxpl_id) +{ + C_DATATYPE data[EXAMPLE_DSET_CHUNK_DIM_SIZE][4 * EXAMPLE_DSET_CHUNK_DIM_SIZE]; + hsize_t dataset_dims[EXAMPLE_DSET_DIMS]; + hsize_t chunk_dims[EXAMPLE_DSET_DIMS]; + hsize_t start[EXAMPLE_DSET_DIMS]; + hsize_t stride[EXAMPLE_DSET_DIMS]; + hsize_t count[EXAMPLE_DSET_DIMS]; + hid_t dset_id = H5I_INVALID_HID; + hid_t dcpl_id = H5I_INVALID_HID; + hid_t file_dataspace = H5I_INVALID_HID; + + /* + * ------------------------------------ + * Setup Dataset Creation Property List + * ------------------------------------ + */ + + dcpl_id = H5Pcreate(H5P_DATASET_CREATE); + + /* + * REQUIRED: Dataset chunking must be enabled to + * apply a data filter to the dataset. + * Chunks in the dataset are of size + * EXAMPLE_DSET_CHUNK_DIM_SIZE x EXAMPLE_DSET_CHUNK_DIM_SIZE. + */ + chunk_dims[0] = EXAMPLE_DSET_CHUNK_DIM_SIZE; + chunk_dims[1] = EXAMPLE_DSET_CHUNK_DIM_SIZE; + H5Pset_chunk(dcpl_id, EXAMPLE_DSET_DIMS, chunk_dims); + + /* Set filter to be applied to created datasets */ + set_filter(dcpl_id); + + /* + * ------------------------------------ + * Define the dimensions of the dataset + * and create it + * ------------------------------------ + */ + + /* + * Create a dataset composed of 4 chunks + * per MPI rank. The first dataset dimension + * scales according to the number of MPI ranks. + * The second dataset dimension stays fixed + * according to the chunk size. + */ + dataset_dims[0] = EXAMPLE_DSET_CHUNK_DIM_SIZE * mpi_size; + dataset_dims[1] = 4 * EXAMPLE_DSET_CHUNK_DIM_SIZE; + + file_dataspace = H5Screate_simple(EXAMPLE_DSET_DIMS, dataset_dims, NULL); + + /* Create the dataset */ + dset_id = H5Dcreate2(file_id, EXAMPLE_DSET1_NAME, HDF5_DATATYPE, file_dataspace, H5P_DEFAULT, dcpl_id, + H5P_DEFAULT); + + /* + * ------------------------------------ + * Setup selection in the dataset for + * each MPI rank + * ------------------------------------ + */ + + /* + * Each MPI rank's selection covers a + * single chunk in the first dataset + * dimension. Each MPI rank's selection + * covers 4 chunks in the second dataset + * dimension. This leads to each MPI rank + * writing to 4 chunks of the dataset. + */ + start[0] = mpi_rank * EXAMPLE_DSET_CHUNK_DIM_SIZE; + start[1] = 0; + stride[0] = 1; + stride[1] = 1; + count[0] = EXAMPLE_DSET_CHUNK_DIM_SIZE; + count[1] = 4 * EXAMPLE_DSET_CHUNK_DIM_SIZE; + + H5Sselect_hyperslab(file_dataspace, H5S_SELECT_SET, start, stride, count, NULL); + + /* + * -------------------------------------- + * Fill data buffer with MPI rank's rank + * value to make it easy to see which + * part of the dataset each rank wrote to + * -------------------------------------- + */ + + fill_databuf(start, count, stride, &data[0][0]); + + /* + * --------------------------------- + * Write to the dataset collectively + * --------------------------------- + */ + + H5Dwrite(dset_id, HDF5_DATATYPE, H5S_BLOCK, file_dataspace, dxpl_id, data); + + /* + * -------------- + * Close HDF5 IDs + * -------------- + */ + + H5Sclose(file_dataspace); + H5Pclose(dcpl_id); + H5Dclose(dset_id); +} + +/* + * Routine to write to a dataset in a fashion + * where every chunk in the dataset is written + * to by every MPI rank. This will generally + * give the worst performance as the MPI ranks + * will need the most amount of inter-process + * communication. + */ +static void +write_dataset_overlap(hid_t file_id, hid_t dxpl_id) +{ + C_DATATYPE *data = NULL; + hsize_t dataset_dims[EXAMPLE_DSET_DIMS]; + hsize_t chunk_dims[EXAMPLE_DSET_DIMS]; + hsize_t start[EXAMPLE_DSET_DIMS]; + hsize_t stride[EXAMPLE_DSET_DIMS]; + hsize_t count[EXAMPLE_DSET_DIMS]; + hid_t dset_id = H5I_INVALID_HID; + hid_t dcpl_id = H5I_INVALID_HID; + hid_t file_dataspace = H5I_INVALID_HID; + + /* + * ------------------------------------ + * Setup Dataset Creation Property List + * ------------------------------------ + */ + + dcpl_id = H5Pcreate(H5P_DATASET_CREATE); + + /* + * REQUIRED: Dataset chunking must be enabled to + * apply a data filter to the dataset. + * Chunks in the dataset are of size + * mpi_size x EXAMPLE_DSET_CHUNK_DIM_SIZE. + */ + chunk_dims[0] = mpi_size; + chunk_dims[1] = EXAMPLE_DSET_CHUNK_DIM_SIZE; + H5Pset_chunk(dcpl_id, EXAMPLE_DSET_DIMS, chunk_dims); + + /* Set filter to be applied to created datasets */ + set_filter(dcpl_id); + + /* + * ------------------------------------ + * Define the dimensions of the dataset + * and create it + * ------------------------------------ + */ + + /* + * Create a dataset composed of N chunks, + * where N is the number of MPI ranks. The + * first dataset dimension scales according + * to the number of MPI ranks. The second + * dataset dimension stays fixed according + * to the chunk size. + */ + dataset_dims[0] = mpi_size * chunk_dims[0]; + dataset_dims[1] = EXAMPLE_DSET_CHUNK_DIM_SIZE; + + file_dataspace = H5Screate_simple(EXAMPLE_DSET_DIMS, dataset_dims, NULL); + + /* Create the dataset */ + dset_id = H5Dcreate2(file_id, EXAMPLE_DSET2_NAME, HDF5_DATATYPE, file_dataspace, H5P_DEFAULT, dcpl_id, + H5P_DEFAULT); + + /* + * ------------------------------------ + * Setup selection in the dataset for + * each MPI rank + * ------------------------------------ + */ + + /* + * Each MPI rank's selection covers + * part of every chunk in the first + * dimension. Each MPI rank's selection + * covers all of every chunk in the + * second dimension. This leads to + * each MPI rank writing an equal + * amount of data to every chunk + * in the dataset. + */ + start[0] = mpi_rank; + start[1] = 0; + stride[0] = chunk_dims[0]; + stride[1] = 1; + count[0] = mpi_size; + count[1] = EXAMPLE_DSET_CHUNK_DIM_SIZE; + + H5Sselect_hyperslab(file_dataspace, H5S_SELECT_SET, start, stride, count, NULL); + + /* + * -------------------------------------- + * Fill data buffer with MPI rank's rank + * value to make it easy to see which + * part of the dataset each rank wrote to + * -------------------------------------- + */ + + data = malloc(mpi_size * EXAMPLE_DSET_CHUNK_DIM_SIZE * sizeof(C_DATATYPE)); + + fill_databuf(start, count, stride, data); + + /* + * --------------------------------- + * Write to the dataset collectively + * --------------------------------- + */ + + H5Dwrite(dset_id, HDF5_DATATYPE, H5S_BLOCK, file_dataspace, dxpl_id, data); + + free(data); + + /* + * -------------- + * Close HDF5 IDs + * -------------- + */ + + H5Sclose(file_dataspace); + H5Pclose(dcpl_id); + H5Dclose(dset_id); +} + +int +main(int argc, char **argv) +{ + MPI_Comm comm = MPI_COMM_WORLD; + MPI_Info info = MPI_INFO_NULL; + hid_t file_id = H5I_INVALID_HID; + hid_t fapl_id = H5I_INVALID_HID; + hid_t dxpl_id = H5I_INVALID_HID; + char *par_prefix = NULL; + char filename[PATH_MAX]; + + MPI_Init(&argc, &argv); + MPI_Comm_size(comm, &mpi_size); + MPI_Comm_rank(comm, &mpi_rank); + + /* + * ---------------------------------- + * Start parallel access to HDF5 file + * ---------------------------------- + */ + + /* Setup File Access Property List with parallel I/O access */ + fapl_id = H5Pcreate(H5P_FILE_ACCESS); + H5Pset_fapl_mpio(fapl_id, comm, info); + + /* + * OPTIONAL: Set collective metadata reads on FAPL to allow + * parallel writes to filtered datasets to perform + * better at scale. While not strictly necessary, + * this is generally recommended. + */ + H5Pset_all_coll_metadata_ops(fapl_id, true); + + /* + * OPTIONAL: Set the latest file format version for HDF5 in + * order to gain access to different dataset chunk + * index types and better data encoding methods. + * While not strictly necessary, this is generally + * recommended. + */ + H5Pset_libver_bounds(fapl_id, H5F_LIBVER_LATEST, H5F_LIBVER_LATEST); + + /* Parse any parallel prefix and create filename */ + par_prefix = getenv("HDF5_PARAPREFIX"); + + snprintf(filename, PATH_MAX, "%s%s%s", par_prefix ? par_prefix : "", par_prefix ? "/" : "", EXAMPLE_FILE); + + /* Create HDF5 file */ + file_id = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id); + + /* + * -------------------------------------- + * Setup Dataset Transfer Property List + * with collective I/O + * -------------------------------------- + */ + + dxpl_id = H5Pcreate(H5P_DATASET_XFER); + + /* + * REQUIRED: Setup collective I/O for the dataset + * write operations. Parallel writes to + * filtered datasets MUST be collective, + * even if some ranks have no data to + * contribute to the write operation. + * + * Refer to the 'ph5_filtered_writes_no_sel' + * example to see how to setup a dataset + * write when one or more MPI ranks have + * no data to contribute to the write + * operation. + */ + H5Pset_dxpl_mpio(dxpl_id, H5FD_MPIO_COLLECTIVE); + + /* + * -------------------------------- + * Create and write to each dataset + * -------------------------------- + */ + + /* + * Write to a dataset in a fashion where no + * chunks in the dataset are written to by + * more than 1 MPI rank. This will generally + * give the best performance as the MPI ranks + * will need the least amount of inter-process + * communication. + */ + write_dataset_no_overlap(file_id, dxpl_id); + + /* + * Write to a dataset in a fashion where + * every chunk in the dataset is written + * to by every MPI rank. This will generally + * give the worst performance as the MPI ranks + * will need the most amount of inter-process + * communication. + */ + write_dataset_overlap(file_id, dxpl_id); + + /* + * ------------------ + * Close all HDF5 IDs + * ------------------ + */ + + H5Pclose(dxpl_id); + H5Pclose(fapl_id); + H5Fclose(file_id); + + printf("PHDF5 example finished with no errors\n"); + + /* + * ------------------------------------ + * Cleanup created HDF5 file and finish + * ------------------------------------ + */ + + cleanup(filename); + + MPI_Finalize(); + + return 0; +} + +#else + +int +main(void) +{ + printf("HDF5 not configured with parallel support or parallel filtered writes are disabled!\n"); + return 0; +} + +#endif |