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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* All rights reserved. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/* This example shows different data writing patterns to generate data files
* that will exhibit substantially different data read speed. The files
* contain 2-D chunk storage datasets.
* The 2 writing patterns are:
* 1. Random--chunks are wriitten in the random order.
* 2. ByRow--chunks are written by row order.
*/
#include <stdlib.h>
#include <string.h>
#include "../Perf/h5slab.h"
#include "hdf5.h"
/* Write the chunks in the row order. This provides good and bad read
* performance if the read pattern is by row and by column respectively.
*
* Created by Albert Cheng and Christian Chilan 2010/7/13.
*/
int
createfilebyrow(void)
{
hid_t file_id, dset_id, filespace, memspace, fapl, dxpl, dcpl;
hsize_t dimsf[2], count[2], offset[2], chunk_dims[2] = {CX, CY};
char *data, dataval, table[RC];
unsigned long i, j, l, cx;
fapl = H5Pcreate(H5P_FILE_ACCESS);
dcpl = H5Pcreate(H5P_DATASET_CREATE);
dxpl = H5Pcreate(H5P_DATASET_XFER);
H5Pset_chunk(dcpl, 2, chunk_dims);
fapl = dxpl = H5P_DEFAULT;
file_id = H5Fcreate("row_alloc.h5", H5F_ACC_TRUNC, H5P_DEFAULT, fapl);
dimsf[0] = NX;
dimsf[1] = NY;
filespace = H5Screate_simple(2, dimsf, NULL);
dset_id = H5Dcreate(file_id, "dataset1", H5T_NATIVE_CHAR, filespace, H5P_DEFAULT, dcpl, H5P_DEFAULT);
count[0] = CX;
count[1] = NY;
memspace = H5Screate_simple(2, count, NULL);
data = (char *)malloc(count[0] * count[1] * sizeof(char));
/* writing the whole chunked rows each time. */
for (l = 0; l < RC; l++) {
offset[0] = l * CX;
offset[1] = 0;
/* fill with values according to row number */
for (i = 0; i < count[0]; i++)
for (j = 0; j < count[1]; j++)
data[i * count[1] + j] = l;
H5Sselect_hyperslab(filespace, H5S_SELECT_SET, offset, NULL, count, NULL);
H5Dwrite(dset_id, H5T_NATIVE_CHAR, memspace, filespace, dxpl, data);
}
free(data);
H5Dclose(dset_id);
H5Sclose(filespace);
H5Sclose(memspace);
H5Pclose(dxpl);
H5Pclose(dcpl);
H5Pclose(fapl);
H5Fclose(file_id);
return 0;
}
/* Write the chunks in a random pattern. This provides a read performance
* worse than when the chunks are written and read in the same order, whether
* it is by row or by column.
*
* Created by Albert Cheng and Christian Chilan 2010/7/13.
*/
int
createfilerandom(void)
{
hid_t file_id, dset_id, filespace, memspace, fapl, dxpl, dcpl;
hsize_t dimsf[2], count[2], offset[2], chunk_dims[2] = {CX, CY};
char *data, table[RC][CC];
unsigned long i, j, cx, cy;
fapl = H5Pcreate(H5P_FILE_ACCESS);
dcpl = H5Pcreate(H5P_DATASET_CREATE);
dxpl = H5Pcreate(H5P_DATASET_XFER);
H5Pset_chunk(dcpl, 2, chunk_dims);
fapl = dxpl = H5P_DEFAULT;
file_id = H5Fcreate("random_alloc.h5", H5F_ACC_TRUNC, H5P_DEFAULT, fapl);
dimsf[0] = NX;
dimsf[1] = NY;
filespace = H5Screate_simple(2, dimsf, NULL);
dset_id = H5Dcreate(file_id, "dataset1", H5T_NATIVE_CHAR, filespace, H5P_DEFAULT, dcpl, H5P_DEFAULT);
count[0] = CX;
count[1] = CY;
memspace = H5Screate_simple(2, count, NULL);
data = (char *)malloc(count[0] * count[1] * sizeof(char));
for (i = 0; i < RC; i++)
for (j = 0; j < CC; j++)
table[i][j] = 0;
for (i = 0; i < RC * CC; i++) {
do {
cx = rand() % RC;
cy = rand() % CC;
} while (table[cx][cy]);
for (j = 0; j < count[0] * count[1]; j++) {
data[j] = cx + cy;
}
table[cx][cy] = 1;
offset[0] = cx * CX;
offset[1] = cy * CY;
H5Sselect_hyperslab(filespace, H5S_SELECT_SET, offset, NULL, count, NULL);
H5Dwrite(dset_id, H5T_NATIVE_CHAR, memspace, filespace, dxpl, data);
}
free(data);
H5Dclose(dset_id);
H5Sclose(filespace);
H5Sclose(memspace);
H5Pclose(dxpl);
H5Pclose(dcpl);
H5Pclose(fapl);
H5Fclose(file_id);
return 0;
}
int
main(int argc, char **argv)
{
createfilebyrow();
createfilerandom();
}
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