netcdf-c/nc_perf/tst_compress.c

/*
  Copyright 2021, UCAR/Unidata See COPYRIGHT file for copying and
  redistribution conditions.

  This program tests and benchmarks netcdf-4 I/O doing compression.

  This is a sequential version of tst_compress_par.c.

  Also see the file gfs_sample.cdl to see what is being produced by
  this program.

  Ed Hartnett, 11/27/21
*/

#include <config.h>
#include <nc_tests.h>
#include <time.h>
#include <sys/time.h> /* Extra high precision time info. */
#include "err_macros.h"
#include <H5public.h>

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <netcdf.h>
#include <netcdf_par.h>
#include <netcdf_meta.h>

#define TEST_NAME "tst_compress"
#define NUM_META_VARS 7
#define NUM_META_TRIES 2
#define NDIM2 2
#define NDIM4 4
#define NDIM5 5
#define NUM_PROC 4
#define NUM_SHUFFLE_SETTINGS 1
/* #define NUM_DEFLATE_LEVELS 3 */
#define NUM_DEFLATE_LEVELS 1
#define NUM_UNLIM_TRIES 1
#define NUM_NSD_SETTINGS 2
#define THOUSAND 1000
#define NUM_DATA_VARS 3
#define ERR_AWFUL 1
#define NUM_TRIES 2

#define USE_SMALL 1

#ifdef USE_SMALL
#define GRID_XT_LEN 8
#define GRID_YT_LEN 4
#define PFULL_LEN 4
#define PHALF_LEN 5
#else
#define GRID_XT_LEN 3072
#define GRID_YT_LEN 1536
#define PFULL_LEN 127
#define PHALF_LEN 128
#endif /* USE_SMALL */
#define TIME_LEN 1

#define MAX_COMPRESSION_FILTERS 4
char compression_filter_name[MAX_COMPRESSION_FILTERS][NC_MAX_NAME + 1];
int deflate_level[MAX_COMPRESSION_FILTERS][NUM_DEFLATE_LEVELS];
int nsd[NUM_NSD_SETTINGS] = {0, 4};

char dim_name[NDIM5][NC_MAX_NAME + 1] = {"grid_xt", "grid_yt", "pfull",
    "phalf", "time"};
char var_name[NUM_META_VARS][NC_MAX_NAME + 1] = {"grid_xt", "lon", "grid_yt",
    "lat", "pfull", "phalf", "time"};
int var_type[NUM_META_VARS] = {NC_DOUBLE, NC_DOUBLE, NC_DOUBLE, NC_DOUBLE,
    NC_FLOAT, NC_FLOAT, NC_DOUBLE};
int dim_len[NDIM5] = {GRID_XT_LEN, GRID_YT_LEN, PFULL_LEN, PHALF_LEN,
    TIME_LEN};

/* Prototype from tst_utils.c. */
int nc4_timeval_subtract(struct timeval *result, struct timeval *x,
                         struct timeval *y);

/* Get the size of a file in bytes. */
int
get_file_size(char *filename, size_t *file_size)
{
    FILE *fp;
    assert(filename && file_size);

    fp = NCfopen(filename, "r");
    if (fp)
    {
        fseek(fp, 0 , SEEK_END);
        *file_size = ftell(fp);
        fclose(fp);
    }
    return 0;
}

/* Check all the metadata, including coordinate variable data. */
int
check_meta(int ncid, int *data_varid, int s, int f, int deflate, int u,
           size_t phalf_size, size_t phalf_start, float *phalf, size_t *data_start,
           size_t *data_count, size_t pfull_start, size_t pfull_size, float *pfull,
           size_t grid_xt_start, size_t grid_xt_size, double *grid_xt, size_t grid_yt_start,
           size_t grid_yt_size, double *grid_yt, size_t *latlon_start,
           size_t *latlon_count, double *lat, double *lon)
{
    int ndims, nvars, natts, unlimdimid;
    char name_in[NC_MAX_NAME + 1];
    int xtype_in;
    int ndims_in;
    int dimids_in[NDIM4];
    size_t len_in;
    double *grid_xt_in, *grid_yt_in;
    double *lat_in, *lon_in;
    float *phalf_in, *pfull_in;
    int d, v, i;

    /* Check number of dims, vars, atts. */
    if (nc_inq(ncid, &ndims, &nvars, &natts, &unlimdimid)) ERR;
    if (ndims != NDIM5 || nvars != NUM_META_VARS + NUM_DATA_VARS ||
        natts != 0) ERR;
    if (unlimdimid != (u ? 4 : -1)) ERR;

    /* Check the dimensions. */
    for (d = 0; d < NDIM5; d++)
    {
        if (nc_inq_dim(ncid, d, name_in, &len_in)) ERR;
        if (strcmp(name_in, dim_name[d]) || len_in != dim_len[d]) ERR;
    }

    /* Check metadata vars. */
    for (v = 0; v < NUM_META_VARS; v++)
    {
        if (nc_inq_var(ncid, v, name_in, &xtype_in, &ndims_in, dimids_in,
                       &natts)) ERR;
        if (strcmp(name_in, var_name[v]) || xtype_in != var_type[v]) ERR;
    }

    /* Check the values for grid_xt. */
    if (!(grid_xt_in = malloc(grid_xt_size * sizeof(double)))) ERR;
    if (nc_get_vara_double(ncid, 0, &grid_xt_start, &grid_xt_size, grid_xt_in)) ERR;
    for (i = 0; i < grid_xt_size; i++)
        if (grid_xt_in[i] != grid_xt[i]) ERR;
    free(grid_xt_in);

    /* Check the values for lon. */
    if (!(lon_in = malloc(latlon_count[0] * latlon_count[1] * sizeof(double)))) ERR;
    if (nc_get_vara_double(ncid, 1, latlon_start, latlon_count, lon_in)) ERR;
    for (i = 0; i < latlon_count[0] * latlon_count[1]; i++)
        if (lon_in[i] != lon[i]) ERR;
    free(lon_in);

    /* Check the values for grid_yt. */
    if (!(grid_yt_in = malloc(grid_yt_size * sizeof(double)))) ERR;
    if (nc_get_vara_double(ncid, 2, &grid_yt_start, &grid_yt_size, grid_yt_in)) ERR;
    for (i = 0; i < grid_yt_size; i++)
        if (grid_yt_in[i] != grid_yt[i]) ERR;
    free(grid_yt_in);

    /* Check the values for lat. */
    if (!(lat_in = malloc(latlon_count[0] * latlon_count[1] * sizeof(double)))) ERR;
    if (nc_get_vara_double(ncid, 1, latlon_start, latlon_count, lat_in)) ERR;
    for (i = 0; i < latlon_count[0] * latlon_count[1]; i++)
        if (lat_in[i] != lat[i]) ERR;
    free(lat_in);

    /* Check the values for pfull. */
    if (!(pfull_in = malloc(pfull_size * sizeof(float)))) ERR;
    if (nc_get_vara_float(ncid, 4, &pfull_start, &pfull_size, pfull_in)) ERR;
    for (i = 0; i < pfull_size; i++)
        if (pfull_in[i] != pfull[i]) ERR;
    free(pfull_in);

    /* Check the values for phalf. */
    if (!(phalf_in = malloc(phalf_size * sizeof(float)))) ERR;
    if (nc_get_vara_float(ncid, 5, &phalf_start, &phalf_size, phalf_in)) ERR;
    for (i = 0; i < phalf_size; i++)
        if (phalf_in[i] != phalf[i]) ERR;
    free(phalf_in);

    return 0;
}

/* Write all the metadata, including coordinate variable data. */
int
write_meta(int ncid, int *data_varid, int s, int f, int nsd, int deflate, int u,
           size_t phalf_size, size_t phalf_start, float *phalf, size_t *data_start,
           size_t *data_count, size_t pfull_start, size_t pfull_size, float *pfull,
           size_t grid_xt_start, size_t grid_xt_size, double *grid_xt, size_t grid_yt_start,
           size_t grid_yt_size, double *grid_yt, size_t *latlon_start,
           size_t *latlon_count, double *lat, double *lon)
{
    int dimid[NDIM5];
    int dimid_data[NDIM4];
    int varid[NUM_META_VARS];
    double value_time = 2.0;
    int dv;

    /* Turn off fill mode. */
    if (nc_set_fill(ncid, NC_NOFILL, NULL)) ERR;

    /* Define dimension grid_xt. */
    if (nc_def_dim(ncid, dim_name[0], dim_len[0], &dimid[0])) ERR;

    /* Define dimension grid_yt. */
    if (nc_def_dim(ncid, dim_name[1], dim_len[1], &dimid[1])) ERR;

    /* Define variable grid_xt. */
    if (nc_def_var(ncid, var_name[0], var_type[0], 1, &dimid[0], &varid[0])) ERR;

    /* Define variable lon. */
    if (nc_def_var(ncid, var_name[1], var_type[1], 2, dimid, &varid[1])) ERR;
    if (nc_put_att_text(ncid, varid[1], "long_name", strlen("T-cell longitude"), "T-cell longitude")) ERR;
    if (nc_put_att_text(ncid, varid[1], "units", strlen("degrees_E"), "degrees_E")) ERR;

    if (nc_put_att_text(ncid, varid[0], "cartesian_axis", strlen("X"), "X")) ERR;

    /* Define variable grid_yt. */
    if (nc_def_var(ncid, var_name[2], var_type[2], 1, &dimid[1], &varid[2])) ERR;

    /* Define variable lat. */
    if (nc_def_var(ncid, var_name[3], var_type[3], 2, dimid, &varid[3])) ERR;
    if (nc_put_att_text(ncid, varid[3], "long_name", strlen("T-cell latitude"), "T-cell latitude")) ERR;
    if (nc_put_att_text(ncid, varid[3], "units", strlen("degrees_N"), "degrees_N")) ERR;

    if (nc_put_att_text(ncid, varid[2], "cartesian_axis", strlen("Y"), "Y")) ERR;

    /* Define dimension pfull. */
    if (nc_def_dim(ncid, dim_name[2], dim_len[2], &dimid[2])) ERR;

    /* Define variable pfull and write data. */
    if (nc_def_var(ncid, var_name[4], var_type[4], 1, &dimid[2], &varid[4])) ERR;
    if (nc_enddef(ncid)) ERR;
    if (nc_put_vara_float(ncid, varid[4], &pfull_start, &pfull_size, pfull)) ERR;
    if (nc_redef(ncid)) ERR;

    /* Define dimension phalf. This dim is only used by the phalf coord var. */
    if (nc_def_dim(ncid, dim_name[3], dim_len[3], &dimid[3])) ERR;

    /* Define coord variable phalf and write data. */
    if (nc_def_var(ncid, var_name[5], var_type[5], 1, &dimid[3], &varid[5])) ERR;
    if (nc_enddef(ncid)) ERR;
    if (nc_put_vara_float(ncid, varid[5], &phalf_start, &phalf_size, phalf)) ERR;
    if (nc_redef(ncid)) ERR;

    /* Define dimension time, sometimes the unlimited dimension,
     * sometimes a fixed dim of 1. */
    if (nc_def_dim(ncid, dim_name[4], (u ? NC_UNLIMITED : 1), &dimid[4])) ERR;

    /* Define variable time and write data. */
    if (nc_def_var(ncid, var_name[6], var_type[6], 1, &dimid[4], &varid[6])) ERR;
    if (nc_enddef(ncid)) ERR;

    /* In NOAA code, do all processors write the single time value? */
    if (nc_put_var_double(ncid, varid[6], &value_time)) ERR;;
    if (nc_redef(ncid)) ERR;

    /* Write variable grid_xt data. */
    if (nc_enddef(ncid)) ERR;
    if (nc_put_vara_double(ncid, varid[0], &grid_xt_start, &grid_xt_size, grid_xt)) ERR;
    if (nc_redef(ncid)) ERR;

    /* Write lon data. */
    if (nc_enddef(ncid)) ERR;
    if (nc_put_vara_double(ncid, varid[1], latlon_start, latlon_count, lon)) ERR;
    if (nc_redef(ncid)) ERR;

    /* Write grid_yt data. */
    if (nc_enddef(ncid)) ERR;
    if (nc_put_vara_double(ncid, varid[2], &grid_yt_start, &grid_yt_size, grid_yt)) ERR;
    if (nc_redef(ncid)) ERR;

    /* Write lat data. */
    if (nc_enddef(ncid)) ERR;
    if (nc_put_vara_double(ncid, varid[3], latlon_start, latlon_count, lat)) ERR;

    /* Specify dimensions for our data vars. */
    dimid_data[0] = dimid[4];
    dimid_data[1] = dimid[2];
    dimid_data[2] = dimid[1];
    dimid_data[3] = dimid[0];

    /* Define data variables. */
    for (dv = 0; dv < NUM_DATA_VARS; dv++)
    {
        char data_var_name[NC_MAX_NAME + 1];

        sprintf(data_var_name, "var_%d", dv);
        if (nc_redef(ncid)) ERR;
        if (nc_def_var(ncid, data_var_name, NC_FLOAT, NDIM4, dimid_data, &data_varid[dv])) ERR;

        if (nsd)
            if (nc_def_var_quantize(ncid, data_varid[dv], NC_QUANTIZE_BITGROOM, nsd)) ERR;

        /* Setting any filter only will work for HDF5-1.10.3 and later */
        /* versions. Do nothing for "none". */
        if (!strcmp(compression_filter_name[f], "zlib"))
            if (nc_def_var_deflate(ncid, data_varid[dv], s, 1, deflate)) ERR;

#if NC_HAS_SZIP_WRITE
        if (!strcmp(compression_filter_name[f], "szip"))
            if (nc_def_var_szip(ncid, data_varid[dv], 32, 32)) ERR;
#endif /* NC_HAS_SZIP_WRITE */

        if (nc_enddef(ncid)) ERR;
    }

    if (nc_redef(ncid)) ERR;
    if (nc_put_att_text(ncid, varid[0], "long_name", strlen("T-cell longitude"), "T-cell longitude")) ERR;
    if (nc_put_att_text(ncid, varid[0], "units", strlen("degrees_E"), "degrees_E")) ERR;

    if (nc_put_att_text(ncid, varid[2], "long_name", strlen("T-cell latiitude"), "T-cell latiitude")) ERR;
    if (nc_put_att_text(ncid, varid[2], "units", strlen("degrees_N"), "degrees_N")) ERR;
    if (nc_enddef(ncid)) ERR;

    if (nc_redef(ncid)) ERR;

    for (dv = 0; dv < NUM_DATA_VARS; dv++)
    {
        float compress_err = 42.22;
        int nbits = 5;
        if (nc_put_att_float(ncid, data_varid[dv], "max_abs_compression_error", NC_FLOAT, 1, &compress_err)) ERR;
        if (nc_put_att_int(ncid, data_varid[dv], "nbits", NC_INT, 1, &nbits)) ERR;
    }

    if (nc_enddef(ncid)) ERR;
    return 0;
}

/* Calculate the decomposition of the 2D lat/lon coordinate
 * variables. */
int
decomp_latlon(int *dim_len, size_t *latlon_start,
              size_t *latlon_count, double **lat, double **lon)
{
    int i, j;

    assert(dim_len && latlon_start && latlon_count && lat && lon && !*lat &&
           !*lon);

    /* Size of local arrays (i.e. for this pe) lon and lat data. */
    latlon_start[0] = 0;
    latlon_start[1] = 0;
    latlon_count[0] = dim_len[0];
    latlon_count[1] = dim_len[1];

    /* Allocate storage. */
    if (!(*lon = malloc(latlon_count[0] * latlon_count[1] * sizeof(double)))) ERR;
    if (!(*lat = malloc(latlon_count[0] * latlon_count[1] * sizeof(double)))) ERR;

    /* Now calculate some latlon values to write. */
    for (i = 0; i < latlon_count[0]; i++)
    {
        for (j = 0; j < latlon_count[1]; j++)
        {
            (*lon)[j * latlon_count[0] + i] = 100 + i + j;
            (*lat)[j * latlon_count[0] + i] = 100 + i + j;
        }
    }

    return 0;
}

/* Based on the MPI rank and number of tasks, calculate the
 * decomposition of the 4D data. */
int
decomp_4D(int *dim_len, size_t *start, size_t *count)
{
    /* Time dimension. */
    start[0] = 0;
    count[0] = 1;

    /* Vertical dimension (pfull). */
    count[1] = dim_len[2];
    start[1] = 0;

    start[2] = 0;
    start[3] = 0;
    count[2] = dim_len[1];
    count[3] = dim_len[0];

    return 0;
}

/* Decompose the grid_xt and grid_yt coordinate vars, and also come up
 * with some data. */
int
decomp_grid(int *dim_len, size_t *grid_xt_start, size_t *grid_xt_size,
            size_t *grid_yt_start, size_t *grid_yt_size, double **grid_xt, double **grid_yt)
{
    int i;

    /* Size of local (i.e. for this pe) grid_xt data. */
    *grid_xt_size = dim_len[0];
    *grid_xt_start = 0;

    /* Size of local (i.e. for this pe) grid_yt data. */
    *grid_yt_size = dim_len[1];
    *grid_yt_start = 0;

    /* Allocate storage for the grid_xy and grid_yt coordinate
     * variable data. */
    if (!(*grid_xt = malloc(*grid_xt_size * sizeof(double)))) ERR;
    if (!(*grid_yt = malloc(*grid_yt_size * sizeof(double)))) ERR;

    /* Fill the grid_xt and grid_yt coordinate data arrays. */
    for (i = 0; i < *grid_xt_size; i++)
        (*grid_xt)[i] = 100 + i;
    for (i = 0; i < *grid_yt_size; i++)
        (*grid_yt)[i] = 100 + i;

    return 0;
}

/* Decompose the pfull and phalf coordinate vars. */
int
decomp_p(size_t *data_count, int *dim_len,
         size_t *phalf_start, size_t *phalf_size, float **phalf,
         size_t *pfull_start, size_t *pfull_size, float **pfull)
{
    int i;

    /* Size of local (i.e. for this pe) phalf data. */
    *phalf_size = dim_len[3];
    *phalf_start = 0;

    *pfull_size = dim_len[2];
    *pfull_start = 0;

    /* Allocate space on this pe to hold the coordinate var data for this pe. */
    if (!(*pfull = malloc(data_count[1] * sizeof(float)))) ERR;
    if (!(*phalf = malloc(*phalf_size * sizeof(float)))) ERR;

    /* Some fake data for this pe to write. */
    for (i = 0; i < data_count[1]; i++)
        (*pfull)[i] = 100 + i;
    for (i = 0; i < *phalf_size; i++)
        (*phalf)[i] = 100 + i;

    return 0;
}

/* Determine what compression filters are present. */
int
find_filters(int *num_compression_filters, char compression_filter_name[][NC_MAX_NAME + 1],
             int deflate_level[][NUM_DEFLATE_LEVELS])
{
    int nfilters = 0;
    int i;

    /* Try with no compression. */
    strcpy(compression_filter_name[nfilters], "none");
    nfilters++;

    /* zlib is always present. */
    strcpy(compression_filter_name[nfilters], "zlib");
    for (i = 0; i < NUM_DEFLATE_LEVELS; i++)
        deflate_level[nfilters][i] = i + 1;
             
    /* deflate_level[nfilters][0] = 1; */
    /* deflate_level[nfilters][1] = 4; */
    /* deflate_level[nfilters][2] = 9; */
    nfilters++;

    /* szip is optionally present. */
#if NC_HAS_SZIP_WRITE
    strcpy(compression_filter_name[nfilters], "szip");
    nfilters++;
#endif /* NC_HAS_SZIP_WRITE */

    *num_compression_filters = nfilters;
    return 0;
}

int
main(int argc, char **argv)
{
    /* For timing. */
    struct timeval start_time, end_time, diff_time;
    int write_1_us;

    int ncid;
    size_t latlon_start[NDIM2], latlon_count[NDIM2];
    size_t data_start[NDIM4], data_count[NDIM4];

    /* Variables. */
    int data_varid[NUM_DATA_VARS];
    size_t pfull_size, pfull_start;
    float *pfull = NULL;
    size_t phalf_size, phalf_start;
    float *phalf = NULL;
    size_t grid_xt_size, grid_xt_start;
    double *grid_xt = NULL;
    size_t grid_yt_size, grid_yt_start;
    double *grid_yt = NULL;
    double *lon = NULL;
    double *lat = NULL;
    float *value_data;

    /* Compression filter info. */
    int num_compression_filters;

    int f, s, n, try;
    int i, j, k, dv, dl;
    int ret;

    /* Determine what compression filters are present. */
    if ((ret = find_filters(&num_compression_filters, compression_filter_name, deflate_level)))
        return ret;

    /* Determine 4D data decomposition to write data vars. */
    if (decomp_4D(dim_len, data_start, data_count)) ERR;

    /* Determine 2D data decomposition to write lat/lon coordinate vars. */
    if (decomp_latlon(dim_len, latlon_start, latlon_count, &lat, &lon)) ERR;

    /* Decompose grid_xt and grid_yt coordiate vars. */
    if (decomp_grid(dim_len, &grid_xt_start, &grid_xt_size,
                    &grid_yt_start, &grid_yt_size, &grid_xt, &grid_yt)) ERR;

    /* Decompose phalf and pfull. */
    if (decomp_p(data_count, dim_len, &phalf_start,
                 &phalf_size, &phalf, &pfull_start, &pfull_size, &pfull)) ERR;

    /* printf("%d: data_count[3] %ld data_count[2] %ld data_count[1] %ld\n", my_rank, */
    /*        data_count[3], data_count[2], data_count[1]); */

    /* Allocate space to hold the data. */
    if (!(value_data = malloc(data_count[3] * data_count[2] * data_count[1] *
                              sizeof(float)))) ERR;

    /* Create some data. */
    size_t cnt = 0;
    for (k = 0; k < data_count[1]; k++)
    {
        for (j = 0; j < data_count[2]; j++)
        {
            for(i = 0; i < data_count[3]; i++)
            {
                /* value_data[cnt] = (-1 * i%2) * my_rank * 1000 + cnt / sqrt(my_rank + cnt + 1) - (-1 * i%3 * i); */
                value_data[cnt] = (-1 * i%2) + cnt / sqrt(cnt + 1) - (-1 * i%2 * i);
                /* printf("%d: value_data[%ld] %g\n", my_rank, cnt, value_data[cnt]); */
                cnt++;
            }
        }
    }

    printf("Benchmarking creation of file similar to one produced by the UFS.\n");
    printf("comp, level, nsd, shuffle, data wr rate (MB/s), file size (MB)\n");
    /* for (f = 0; f < num_compression_filters; f++) */
    for (try = 0; try < NUM_TRIES; try++)
    {
        printf("try %d:\n", try);
        for (f = 0; f < 2; f++)
        {
            /* for (s = 0; s < NUM_SHUFFLE_SETTINGS; s++) */
            for (s = 0; s < 1; s++)
            {
                /* for (n = 0; n < NUM_NSD_SETTINGS; n++) */
                for (n = 0; n < 1; n++)
                {
                    for (dl = 0; dl < NUM_DEFLATE_LEVELS; dl++)
                    {
                        size_t file_size;
                        char file_name[NC_MAX_NAME * 3 + 1];

                        /* No deflate levels for szip or none. */
                        if (!strcmp(compression_filter_name[f], "szip") && dl) continue;
                        if (!strcmp(compression_filter_name[f], "none") && dl) continue;

                        /* Use the same filename every time, so we don't
                         * create many large files, just one. ;-) */
                        sprintf(file_name, "%s.nc", TEST_NAME);

                        /* Remove the last file. Ignore errors. */
                        remove(file_name);

                        /* nc_set_log_level(3); */
                        /* Create a netcdf-4 file. */
                        if (nc_create(file_name, NC_NETCDF4, &ncid)) ERR;
                        if (write_meta(ncid, data_varid, s, f, nsd[n], deflate_level[f][dl], 0,
                                       phalf_size, phalf_start, phalf,
                                       data_start, data_count, pfull_start, pfull_size, pfull, grid_xt_start,
                                       grid_xt_size, grid_xt, grid_yt_start,
                                       grid_yt_size, grid_yt, latlon_start,
                                       latlon_count, lat, lon)) ERR;

                        if (gettimeofday(&start_time, NULL)) ERR;

                        /* Write one record each of the data variables. */
                        for (dv = 0; dv < NUM_DATA_VARS; dv++)
                        {
                            /* printf("%d: data_start %ld %ld %ld %ld data_count %ld %ld %ld %ld\n", my_rank, data_start[0], data_start[1], */
                            /*        data_start[2], data_start[3], data_count[0], data_count[1], data_count[2], data_count[3]); */
                            if (nc_put_vara_float(ncid, data_varid[dv], data_start, data_count,
                                                  value_data)) ERR;
                            if (nc_redef(ncid)) ERR;
                        }

                        /* Close the file. */
                        if (nc_close(ncid)) ERR;

                        /* Stop the data timer. */
                        if (gettimeofday(&end_time, NULL)) ERR;
                        if (nc4_timeval_subtract(&diff_time, &end_time, &start_time)) ERR;
                        write_1_us = (int)diff_time.tv_sec * MILLION + (int)diff_time.tv_usec;
                        /* printf("write_1_us %d\n", write_1_us); */

                        /* Get the file size. */
                        if (get_file_size(file_name, &file_size)) ERR;

                        /* Check the file metadata for correctness. */
                        if (nc_open(file_name, NC_NOWRITE, &ncid)) ERR;
                        if (check_meta(ncid, data_varid, s, f, deflate_level[f][dl], 0,
                                       phalf_size, phalf_start, phalf,
                                       data_start, data_count, pfull_start, pfull_size,
                                       pfull, grid_xt_start, grid_xt_size, grid_xt,
                                       grid_yt_start, grid_yt_size, grid_yt, latlon_start,
                                       latlon_count, lat, lon)) ERR;
                        if (nc_close(ncid)) ERR;

                        /* Print out results. */
                        {
                            float data_size, data_rate;
                            data_size = (NUM_DATA_VARS * dim_len[0] * dim_len[1] * dim_len[2] *
                                         dim_len[4] * sizeof(float))/MILLION;
                            /* printf("data_size %f write_1_us / MILLION %g\n", data_size, (float)write_1_us/MILLION); */
                            data_rate = (float)data_size / ((float)write_1_us / MILLION);
                            printf("%s, %d, %d, %d, %g, %g\n", compression_filter_name[f],
                                   deflate_level[f][dl], nsd[n], s,
                                   data_rate, (float)file_size/MILLION);
                        }
                    } /* next deflate level */
                } /* next nsd */
            } /* next shuffle filter test */
        } /* next compression filter (zlib and szip) */
    } /* next try */

    /* Free resources. */
    if (grid_xt)
        free(grid_xt);
    if (grid_yt)
        free(grid_yt);
    if (pfull)
        free(pfull);
    if (phalf)
        free(phalf);
    if (lon)
        free(lon);
    if (lat)
        free(lat);
    free(value_data);

    SUMMARIZE_ERR;
    FINAL_RESULTS;

    return 0;
}