[svn-r4592] Purpose:

    New addition
Description:
    Initial version of the Parallel I/O performance measurement program.
    Not fully implemented yet but checking them in before I may destroy
    them by accident.
    Don't run this in small file system (like AFS or eirene) since it
    generates gigabytes test files.
Platforms tested:
    modi4 64bits.  It compiled and ran but took a long time because
    the current test parametes are too "wild".

1 files changed, 832 insertions, 0 deletions

diff --git a/perform/pio_engine.c b/perform/pio_engine.c
new file mode 100644
index 0000000..f54114c
--- /dev/null
+++ b/perform/pio_engine.c
@@ -0,0 +1,832 @@
+/* 
+ * Author: Albert Cheng of NCSA, Oct 24, 2001.
+ */
+
+#include "hdf5.h"
+#ifdef H5_HAVE_PARALLEL
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include "pio_perf.h"
+#include "pio_timer.h"
+#ifdef OLDSTUFF
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/time.h>
+#endif /* OLDSTUFF */
+#include <mpi.h>
+#ifndef MPI_FILE_NULL           /*MPIO may be defined in mpi.h already       */
+#   include <mpio.h>
+#endif
+
+
+/* Macro definitions */
+#define GOTOERROR(errcode)	{ret_code=errcode; goto done;}
+#define GOTODONE		{goto done;}
+#define ERRMSG(mesg) {                                            \
+	fprintf(stderr, "Proc %d: ", myrank);				       \
+        fprintf(stderr, "*** Assertion failed (%s) at line %4d in %s\n",       \
+	    mesg, (int)__LINE__, __FILE__);     			       \
+}
+#define MSG(mesg) {                                            \
+	fprintf(stderr, "Proc %d: ", myrank);				       \
+        fprintf(stderr, "(%s) at line %4d in %s\n",       \
+	    mesg, (int)__LINE__, __FILE__);     			       \
+}
+/* Verify:
+ * if val is false (0), print mesg.
+ */
+#define VRFY(val, mesg) do {                                    \
+    if (!val) {                                                 \
+	ERRMSG(mesg);						\
+	GOTOERROR(1);					        \
+    }                                                           \
+} while(0)
+
+#ifndef HDmalloc
+#define HDmalloc(x)		malloc(x)
+#endif
+
+#ifndef HDfree
+#define HDfree(x)		free(x)
+#endif
+
+#ifndef HDopen
+#ifdef O_BINARY
+#define HDopen(S,F,M)           open(S,F|_O_BINARY,M)
+#else
+#define HDopen(S,F,M)           open(S,F,M)
+#endif
+#endif
+
+#ifndef HDclose
+#define HDclose(F)		close(F)
+#endif
+
+#ifndef HDseek
+#define HDseek(F,L,W)		lseek(F,L,W)
+#endif
+
+#ifndef HDwrite
+#define HDwrite(F,B,S)		write(F,B,S)
+#endif
+
+#ifndef HDread
+#define HDread(F,B,S)		read(F,B,S)
+#endif
+
+/* Raw I/O macros */
+#define RAWCREATE(fn)		HDopen(fn, O_CREAT|O_TRUNC|O_RDWR, 0600)
+#define RAWOPEN(fn, F)	HDopen(fn, F, 0600)
+#define RAWCLOSE(F)	HDclose(F)
+#define RAWSEEK(F,L)	HDseek(F,L,SEEK_SET)
+#define RAWWRITE(F,B,S)	HDwrite(F,B,S)
+#define RAWREAD(F,B,S)	HDread(F,B,S)
+
+
+
+#ifdef OLDSTUFF
+hid_t dataset;		/* Dataset ID */
+char	*meta_ext, *raw_ext;	/* holds the meta and raw file extension if */
+				/* opt_split_vfd is set */
+
+
+/* DEFAULT VALUES FOR OPTIONS */
+int64_t opt_block     = 1048576*16;
+int     opt_iter      = 1;
+int     opt_stripe    = -1;
+int     opt_correct   = 0;
+int     amode         = O_RDWR | O_CREAT;
+char    opt_file[256] = "/tmp/test.out\0";
+char    opt_pvfstab[256] = "notset\0";
+int     opt_pvfstab_set = 0;
+
+/* function prototypes */
+double Wtime(void);
+
+extern int errno;
+extern int debug_on;
+
+/* globals needed for getopt */
+extern char *optarg;
+extern int optind, opterr;
+#endif  /* old stuff */
+
+int
+dopio(parameters param)
+{
+    MPI_Comm	comm = MPI_COMM_NULL;
+    int		myrank;
+    int		nprocs=1;
+    int 		ret_code=0;			/* return code */
+    iotype		iot;
+    char		fname[256];
+    unsigned int	maxprocs;
+    unsigned int	nfiles, nf;
+    unsigned long	ndsets, nd;
+    unsigned long	nelmts;
+    unsigned int	niters;
+    unsigned long	nelmts_towrite, nelmts_written;
+    unsigned long	nelmts_toread, nelmts_read;
+    size_t		elmt_size;
+    off_t		dset_offset;		/*dataset offset in a file */
+    off_t		next_offset;		/*offset of next I/O */
+    int			rc;			/*routine return code */
+    int			color;			/*for communicator creation */
+    int			mrc;			/*mpi return code */
+    char		*buffer=NULL;		/*data buffer pointer */
+    size_t		buffer_size=1024*1024;	/*data buffer size, 1MB */
+    size_t		nelmts_in_buffer;	/*Number of elmts the buffer*/
+    						/*can hold.*/
+    size_t		dset_size;		/*one dataset size in Byte*/
+    int			rawfd=-1;		/*Raw IO file handle */
+    MPI_File		mpifd=MPI_FILE_NULL;	/*MPI IO file handle */
+    /* hdf5 variables */
+    hid_t		acc_tpl=-1;		/* File access templates */
+    hid_t		h5fd=-1;		/*HDF5 IO file handle */
+    herr_t		hrc;         		/*HDF5 return code */
+    hsize_t		h5dims[1];   		/* dataset dim sizes */
+    hsize_t		h5block[1], h5stride[1], h5count[1];
+    hssize_t		h5start[1];
+    hid_t		h5dset_space_id = -1;  	/*Dataset space ID */
+    hid_t		h5mem_space_id = -1;	/*memory dataspace ID */
+    char		dname[64];		/*dataset name */
+    hid_t		h5ds_id = -1;		/*Dataset handle*/
+
+#ifdef OLDSTUFF
+	char *buf, *tmp, *buf2, *tmp2, *check;
+	int i, j, myrank=0, nprocs=1, err, my_correct = 1, correct, myerrno;
+	double stim, etim;
+	double write_tim = 0;
+	double read_tim = 0;
+	double read_bw, write_bw;
+	double max_read_tim, max_write_tim;
+	double min_read_tim, min_write_tim;
+	double ave_read_tim, ave_write_tim;
+	int64_t iter_jump = 0;
+	int64_t seek_position = 0;
+	MPI_File fh;
+	MPI_Status status;
+	int nchars;
+#endif		/* OLDSTUFF */
+
+
+    /*
+     *Setup parameters and sanity check
+     */
+    /* IO type */
+    iot = param.io_type;
+    switch (iot) {
+    case RAW:
+	/* nothing */
+	break;
+    case MPIO:
+	break;
+    case PHDF5:
+	break;
+    default:
+	/* unknown request */
+	fprintf(stderr, "Unknown IO type request (%d)\n", iot);
+	GOTOERROR(1);
+    }
+
+    /* number of files */
+    nfiles = param.num_files;
+
+    /* number of datasets per file */
+    ndsets = param.num_dsets;
+
+    /* number of elements per dataset */
+    nelmts = param.num_elmts;
+    if (nelmts == 0 ){
+	fprintf(stderr,
+	    "number of elements per dataset must be positive (%lu)\n",
+	    nelmts);
+	GOTOERROR(1);
+    }
+
+    /* number of iterations of reads or writes */
+    niters = param.num_iters;
+
+    /* maximun number of mpi-processes to use */
+    maxprocs = param.max_num_procs;
+    if (maxprocs == 0 ){
+	fprintf(stderr,
+	    "maximun number of process to use must be positive (%u)\n",
+	    maxprocs);
+	GOTOERROR(1);
+    }
+    MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
+    if (maxprocs > nprocs){
+	fprintf(stderr,
+	    "maximun number of process(%d) must be <= process in MPI_COMM_WORLD(%d)\n",
+	    maxprocs, nprocs);
+	GOTOERROR(1);
+    }
+
+
+/* DEBUG*/
+fprintf(stderr, "nfiles=%u\n", nfiles);
+fprintf(stderr, "ndsets=%lu\n", ndsets);
+fprintf(stderr, "nelmts=%lu\n", nelmts);
+fprintf(stderr, "niters=%u\n", niters);
+fprintf(stderr, "maxprocs=%u\n", maxprocs);
+nfiles=3;
+/*ndsets=5; */
+
+    /*
+     *Create a sub communicator for this run
+     *Easier to use the first N processes.
+     */
+    MPI_Comm_rank(comm, &myrank);
+    color = (myrank < maxprocs);
+    mrc = MPI_Comm_split (MPI_COMM_WORLD, color, myrank, &comm);
+    if (mrc!=MPI_SUCCESS) {
+	fprintf(stderr, "MPI_Comm_split failed\n");
+	GOTOERROR(1);
+    }
+
+    if (!color){	/* not involved in this run */
+	mrc = MPI_Comm_free(&comm);
+	GOTODONE;
+    }
+    
+    /* determine the mpi rank of in the new comm */
+    MPI_Comm_size(comm, &nprocs);
+    MPI_Comm_rank(comm, &myrank);
+
+    /* Calculate dataset parameters */
+    /* Data type is always native C int */
+    elmt_size = sizeof(int);
+    dset_size = nelmts * elmt_size;
+
+    /* allocate data buffer */
+    buffer = HDmalloc(buffer_size);
+    if (buffer == NULL){
+	fprintf(stderr, "malloc for data buffer failed\n");
+	GOTOERROR(1);
+    }
+    nelmts_in_buffer = buffer_size/elmt_size;
+
+    /* hdf5 dataset setup */
+    if (iot == PHDF5){
+	/* define a contiquous dataset of nelmts native ints */
+	h5dims[0] = nelmts;
+	h5dset_space_id = H5Screate_simple (1, h5dims, NULL);
+	VRFY((h5dset_space_id >= 0), "H5Screate_simple");
+
+	/* create the memory dataspace */
+	h5dims[0] = nelmts_in_buffer;
+	h5mem_space_id = H5Screate_simple (1, h5dims, NULL);
+	VRFY((h5mem_space_id >= 0), "H5Screate_simple");
+    }
+    
+
+
+
+
+    for (nf=1; nf <= nfiles; nf++){
+	/*
+	 *Open file for write
+	 */
+MSG("creating file");
+	sprintf(fname, "#pio_tmp_%u", nf);
+	switch (iot) {
+	case RAW:
+	    strcat(fname, ".raw");
+	    rawfd = RAWCREATE(fname);
+	    if (rawfd < 0 ){
+		fprintf(stderr, "Raw File Create failed(%s)\n", fname);
+		GOTOERROR(1);
+	    }
+	    break;
+	case MPIO:
+	    strcat(fname, ".mpio");
+	    mrc = MPI_File_open(comm, fname, MPI_MODE_CREATE|MPI_MODE_RDWR,
+		MPI_INFO_NULL, &mpifd);
+	    if (mrc != MPI_SUCCESS){
+		fprintf(stderr, "MPI File Create failed(%s)\n", fname);
+		GOTOERROR(1);
+	    }
+	    break;
+	case PHDF5:
+	    strcat(fname, ".h5");
+	    acc_tpl = H5Pcreate (H5P_FILE_ACCESS);
+	    VRFY((acc_tpl >= 0), "");
+	    hrc = H5Pset_fapl_mpio(acc_tpl, comm, MPI_INFO_NULL);     
+	    VRFY((hrc >= 0), "");
+	    /*do not close acc_tpl. It will used to open file for read later*/
+	    /* create the parallel file */
+	    h5fd=H5Fcreate(fname,H5F_ACC_TRUNC,H5P_DEFAULT,acc_tpl);
+	    if (h5fd < 0){
+		fprintf(stderr, "HDF5 file Create failed(%s)\n", fname);
+		GOTOERROR(1);
+	    }
+	    break;
+	} 
+
+	for (nd=1; nd <= ndsets; nd++){
+	    /* Calculate dataset offset within a file */
+
+	    /* create dataset */
+	    switch (iot){
+	    case RAW:
+	    case MPIO:
+		/* both raw and mpi io just need dataset offset in file*/
+		dset_offset = (nd-1)*dset_size;
+		break;
+	    case PHDF5:
+		sprintf(dname, "Dataset_%lu", nd);
+		h5ds_id = H5Dcreate(h5fd, dname, H5T_NATIVE_INT, h5dset_space_id,
+				    H5P_DEFAULT);
+		VRFY((h5ds_id >= 0), "H5Dcreate");
+		break;
+	    }
+		
+
+	    nelmts_written = 0 ;
+	    while (nelmts_written < nelmts){
+		nelmts_towrite = nelmts - nelmts_written;
+		if (nelmts - nelmts_written >= nelmts_in_buffer){
+		    nelmts_towrite = nelmts_in_buffer;
+		}else{
+		    /* last write of a partial buffer */
+		    nelmts_towrite = nelmts - nelmts_written;
+		}
+
+		/*Prepare write data*/
+		{
+		    int *intptr = (int*)buffer;
+		    int i;
+		    for (i=0; i<nelmts_towrite; i++){
+			*intptr++ = nelmts_towrite+i;
+		    }
+		}
+
+
+		/* Write */
+
+		/* Calculate offset of write within a dataset/file */
+		switch (iot){
+		case RAW:
+		    RAWSEEK(rawfd, dset_offset+nelmts_written*elmt_size);
+		    RAWWRITE(rawfd, buffer, nelmts_towrite*elmt_size);
+		    break;
+		case MPIO:
+		    break;
+		}
+
+
+		nelmts_written += nelmts_towrite;
+fprintf(stderr, "wrote %lu elmts, %lu written\n", nelmts_towrite, nelmts_written);
+	    }
+	/* Calculate write time */
+
+	    /* Close dataset. Only HDF5 needs to do an explicit close. */
+	    if (iot == PHDF5){
+		hrc = H5Dclose(h5ds_id);
+		VRFY((hrc>=0), "HDF5 Dataset Close failed\n");
+		h5ds_id = -1;
+	    }
+	}
+
+	/* Close file for write */
+MSG("closing write file");
+	switch (iot) {
+	case RAW:
+	    rc = RAWCLOSE(rawfd);
+	    VRFY((rc==0), "HDclose");
+	    rawfd = -1;
+	    break;
+	case MPIO:
+	    mrc = MPI_File_close(&mpifd);
+	    if (mrc != MPI_SUCCESS){
+		fprintf(stderr, "MPI File close failed\n");
+		GOTOERROR(1);
+	    }
+	    break;
+	case PHDF5:
+	    hrc=H5Fclose(h5fd);
+	    if (hrc < 0){
+		fprintf(stderr, "HDF5 File Close failed(%s)\n", fname);
+		GOTOERROR(1);
+	    }else{
+		h5fd=-1;
+	    }
+	    break;
+	} 
+
+
+
+
+    /* Open file for read */
+MSG("opening file to read");
+	switch (iot) {
+	case RAW:
+	    rawfd = RAWOPEN(fname, O_RDONLY);
+	    if (rawfd < 0 ){
+		fprintf(stderr, "Raw File Open failed(%s)\n", fname);
+		GOTOERROR(1);
+	    }
+	    break;
+	case MPIO:
+	    mrc = MPI_File_open(comm, fname, MPI_MODE_RDONLY,
+		MPI_INFO_NULL, &mpifd);
+	    if (mrc != MPI_SUCCESS){
+		fprintf(stderr, "MPI File Open failed(%s)\n", fname);
+		GOTOERROR(1);
+	    }
+	    break;
+	case PHDF5:
+	    /* open the parallel file */
+	    h5fd=H5Fopen(fname,H5P_DEFAULT,acc_tpl);
+	    if (h5fd < 0){
+		fprintf(stderr, "HDF5 file Open failed(%s)\n", fname);
+		GOTOERROR(1);
+	    }
+	    /* can release acc_tpl now */
+	    hrc = H5Pclose(acc_tpl);
+	    VRFY((hrc >= 0), "H5Pclose");
+	    acc_tpl = -1;
+	    break;
+	} 
+
+    /* Calculate dataset offset within a file */
+
+    /* Open dataset for read */
+
+    /* Prepare read */
+
+    /* Calculate offset of read within a dataset/file */
+
+    /* Read */
+
+    /* Calculate read time */
+
+    /* Close dataset for read */
+
+    /* Close file for read */
+MSG("closing read file");
+	switch (iot) {
+	case RAW:
+	    rc = RAWCLOSE(rawfd);
+	    VRFY((rc==0), "HDclose");
+	    rawfd = -1;
+	    break;
+	case MPIO:
+	    mrc = MPI_File_close(&mpifd);
+	    if (mrc != MPI_SUCCESS){
+		fprintf(stderr, "MPI File close failed\n");
+		GOTOERROR(1);
+	    }
+	    break;
+	case PHDF5:
+	    hrc=H5Fclose(h5fd);
+	    if (h5fd < 0){
+		fprintf(stderr, "HDF5 file Create failed(%s)\n", fname);
+		GOTOERROR(1);
+	    }else{
+		h5fd=-1;
+	    }
+	    break;
+	} 
+
+    }
+
+done:
+    /* clean up */
+    /* release HDF5 objects */
+    if (acc_tpl != -1){
+	hrc = H5Pclose(acc_tpl);
+	if (hrc < 0){
+	    fprintf(stderr, "HDF5 Property List Close failed\n");
+	    ret_code=1;
+	}
+	else
+	    acc_tpl = -1;
+    }
+    if (h5dset_space_id != -1){
+	hrc = H5Sclose(h5dset_space_id);
+	if (hrc < 0){
+	    fprintf(stderr, "HDF5 Dataset Space Close failed\n");
+	    ret_code=1;
+	}
+	else
+	    h5dset_space_id = -1;
+    }
+    if (h5mem_space_id != -1){
+	hrc = H5Sclose(h5mem_space_id);
+	if (hrc < 0){
+	    fprintf(stderr, "HDF5 Memory Space Close failed\n");
+	    ret_code=1;
+	}
+	else
+	    h5mem_space_id = -1;
+    }
+    if (h5ds_id != -1){
+	hrc = H5Dclose(h5ds_id);
+	if (hrc < 0){
+	    fprintf(stderr, "HDF5 Dataset Close failed\n");
+	    ret_code=1;
+	}
+	else
+	    h5ds_id = -1;
+    }
+
+    /* close any opened files */
+    if (rawfd != -1){
+	rc = HDclose(rawfd);
+	if (rc != 0){
+	    ERRMSG("Raw file close failed");
+	    ret_code=1;
+	}
+	else
+	    rawfd = -1;
+    }
+    if (mpifd != MPI_FILE_NULL){
+	MPI_File_close(&mpifd);
+    }
+    if (h5fd != -1){
+	H5Fclose(h5fd);
+	h5fd=-1;
+    }
+    /* release MPI resources */
+    if (comm != MPI_COMM_NULL){
+	MPI_Comm_free(&comm);
+    }
+    /* release generic resources */
+    if (buffer != NULL){
+	HDfree(buffer);
+	buffer = NULL;
+    }
+fprintf(stderr, "returning with ret_code=%d\n", ret_code);
+    return(ret_code);
+}
+
+#ifdef OLDSTUFF
+int
+original_main()
+{
+
+	/* parse the command line arguments */
+	parse_args(argc, argv);
+
+	if (mynod == 0) printf("# Using hdf5-io calls.\n");
+
+	
+	/* kindof a weird hack- if the location of the pvfstab file was 
+	 * specified on the command line, then spit out this location into
+	 * the appropriate environment variable: */
+	
+#if H5_HAVE_SETENV
+/* no setenv or unsetenv */
+	if (opt_pvfstab_set) {
+		if((setenv("PVFSTAB_FILE", opt_pvfstab, 1)) < 0){
+			perror("setenv");
+			goto die_jar_jar_die;
+		}
+	}
+#endif
+	
+	/* this is how much of the file data is covered on each iteration of
+	 * the test.  used to help determine the seek offset on each
+	 * iteration */
+	iter_jump = nprocs * opt_block;
+		
+	/* setup a buffer of data to write */
+	if (!(tmp = (char *) malloc(opt_block + 256))) {
+		perror("malloc");
+		goto die_jar_jar_die;
+	}
+	buf = tmp + 128 - (((long)tmp) % 128);  /* align buffer */
+
+	if (opt_correct) {
+		/* do the same buffer setup for verifiable data */
+		if (!(tmp2 = (char *) malloc(opt_block + 256))) {
+			perror("malloc2");
+			goto die_jar_jar_die;
+		 }
+		buf2 = tmp + 128 - (((long)tmp) % 128);
+	}
+
+    /* setup file access template with parallel IO access. */
+    if (opt_split_vfd){
+	hid_t mpio_pl;
+
+	mpio_pl = H5Pcreate (H5P_FILE_ACCESS);
+	VRFY((acc_tpl >= 0), "", H5FATAL);
+	ret = H5Pset_fapl_mpio(mpio_pl, MPI_COMM_WORLD, MPI_INFO_NULL);     
+	VRFY((ret >= 0), "", H5FATAL);
+
+	/* set optional allocation alignment */
+	if (opt_alignment*opt_threshold != 1){
+	    ret = H5Pset_alignment(acc_tpl, opt_threshold, opt_alignment );
+	    VRFY((ret >= 0), "H5Pset_alignment succeeded", !H5FATAL);
+	}
+
+	/* setup file access template */
+	acc_tpl = H5Pcreate (H5P_FILE_ACCESS);
+	VRFY((acc_tpl >= 0), "", H5FATAL);
+	ret = H5Pset_fapl_split(acc_tpl, meta_ext, mpio_pl, raw_ext, mpio_pl);
+	VRFY((ret >= 0), "H5Pset_fapl_split succeeded", H5FATAL);
+    }else{
+
+	/* set optional allocation alignment */
+	if (opt_alignment*opt_threshold != 1){
+	    ret = H5Pset_alignment(acc_tpl, opt_threshold, opt_alignment );
+	    VRFY((ret >= 0), "H5Pset_alignment succeeded", !H5FATAL);
+	}
+    }
+
+
+
+	/* now each process writes a block of opt_block chars in round robbin
+	 * fashion until the whole dataset is covered.
+	 */
+	for (j=0; j < opt_iter; j++) {
+	    /* setup a file dataspace selection */
+	    start[0] = (j*iter_jump)+(mynod*opt_block);
+	    stride[0] = block[0] = opt_block;
+	    count[0]= 1;
+	    ret=H5Sselect_hyperslab(file_dataspace, H5S_SELECT_SET, start, stride, count, block); 
+	    VRFY((ret >= 0), "H5Sset_hyperslab succeeded", H5FATAL);
+
+		if (opt_correct) /* fill in buffer for iteration */ {
+			for (i=mynod+j, check=buf; i<opt_block; i++,check++) *check=(char)i;
+		}
+
+		/* discover the starting time of the operation */
+	   MPI_Barrier(MPI_COMM_WORLD);
+	   stim = MPI_Wtime();
+
+    /* write data */
+    ret = H5Dwrite(dataset, H5T_NATIVE_CHAR, mem_dataspace, file_dataspace,
+	    H5P_DEFAULT, buf);					    
+    VRFY((ret >= 0), "H5Dwrite dataset1 succeeded", !H5FATAL);
+
+		/* discover the ending time of the operation */
+	   etim = MPI_Wtime();
+
+	   write_tim += (etim - stim);
+		
+		/* we are done with this "write" iteration */
+	}
+
+    /* close dataset and file */					    
+    ret=H5Dclose(dataset);
+    VRFY((ret >= 0), "H5Dclose succeeded", H5FATAL);
+    ret=H5Fclose(fid);							    
+    VRFY((ret >= 0), "H5Fclose succeeded", H5FATAL);
+
+
+
+	/* wait for everyone to synchronize at this point */
+	MPI_Barrier(MPI_COMM_WORLD);
+
+    /* reopen the file for reading */
+    fid=H5Fopen(opt_file,H5F_ACC_RDONLY,acc_tpl);
+    VRFY((fid >= 0), "", H5FATAL);
+
+    /* open the dataset */
+    dataset = H5Dopen(fid, "Dataset1");
+    VRFY((dataset >= 0), "H5Dopen succeeded", H5FATAL);
+
+    /* we can re-use the same mem_dataspace and file_dataspace
+     * the H5Dwrite used since the dimension size is the same.
+     */
+
+	/* we are going to repeat the read the same pattern the write used */
+	for (j=0; j < opt_iter; j++) {
+	    /* setup a file dataspace selection */
+	    start[0] = (j*iter_jump)+(mynod*opt_block);
+	    stride[0] = block[0] = opt_block;
+	    count[0]= 1;
+	    ret=H5Sselect_hyperslab(file_dataspace, H5S_SELECT_SET, start, stride, count, block); 
+	    VRFY((ret >= 0), "H5Sset_hyperslab succeeded", H5FATAL);
+		/* seek to the appropriate spot give the current iteration and
+		 * rank within the MPI processes */
+
+		/* discover the start time */
+	   MPI_Barrier(MPI_COMM_WORLD);
+	   stim = MPI_Wtime();
+
+    /* read data */
+		/* read in the file data */
+		if (!opt_correct){
+    ret = H5Dread(dataset, H5T_NATIVE_CHAR, mem_dataspace, file_dataspace,
+	    H5P_DEFAULT, buf);					    
+		}
+		else{
+    ret = H5Dread(dataset, H5T_NATIVE_CHAR, mem_dataspace, file_dataspace,
+	    H5P_DEFAULT, buf2);					    
+		}
+		myerrno = errno;
+		/* discover the end time */
+	   etim = MPI_Wtime();
+	   read_tim += (etim - stim);
+    VRFY((ret >= 0), "H5Dwrite dataset1 succeeded", !H5FATAL);
+
+
+	   if (ret < 0) fprintf(stderr, "node %d, read error, loc = %Ld: %s\n",
+			mynod, mynod*opt_block, strerror(myerrno));
+
+		/* if the user wanted to check correctness, compare the write
+		 * buffer to the read buffer */
+		if (opt_correct && memcmp(buf, buf2, opt_block)) {
+			fprintf(stderr, "node %d, correctness test failed\n", mynod);
+			my_correct = 0;
+			MPI_Allreduce(&my_correct, &correct, 1, MPI_INT, MPI_MIN,
+				MPI_COMM_WORLD);
+		}
+
+		/* we are done with this read iteration */
+	}
+
+    /* close dataset and file */					    
+    ret=H5Dclose(dataset);
+    VRFY((ret >= 0), "H5Dclose succeeded", H5FATAL);
+    ret=H5Fclose(fid);							    
+    VRFY((ret >= 0), "H5Fclose succeeded", H5FATAL);
+
+	/* compute the read and write times */
+	MPI_Allreduce(&read_tim, &max_read_tim, 1, MPI_DOUBLE, MPI_MAX,
+		MPI_COMM_WORLD);
+	MPI_Allreduce(&read_tim, &min_read_tim, 1, MPI_DOUBLE, MPI_MIN,
+		MPI_COMM_WORLD);
+	MPI_Allreduce(&read_tim, &ave_read_tim, 1, MPI_DOUBLE, MPI_SUM,
+		MPI_COMM_WORLD);
+
+	/* calculate the average from the sum */
+	ave_read_tim = ave_read_tim / nprocs; 
+
+	MPI_Allreduce(&write_tim, &max_write_tim, 1, MPI_DOUBLE, MPI_MAX,
+		MPI_COMM_WORLD);
+	MPI_Allreduce(&write_tim, &min_write_tim, 1, MPI_DOUBLE, MPI_MIN,
+		MPI_COMM_WORLD);
+	MPI_Allreduce(&write_tim, &ave_write_tim, 1, MPI_DOUBLE, MPI_SUM,
+		MPI_COMM_WORLD);
+
+	/* calculate the average from the sum */
+	ave_write_tim = ave_write_tim / nprocs; 
+	
+	/* print out the results on one node */
+	if (mynod == 0) {
+	   read_bw = ((int64_t)(opt_block*nprocs*opt_iter))/(max_read_tim*1000000.0);
+	   write_bw = ((int64_t)(opt_block*nprocs*opt_iter))/(max_write_tim*1000000.0);
+		
+			printf("nr_procs = %d, nr_iter = %d, blk_sz = %ld\n", nprocs,
+		opt_iter, (long)opt_block);
+			
+			printf("# total_size = %ld\n", (long)(opt_block*nprocs*opt_iter));
+			
+			printf("# Write:  min_time = %f, max_time = %f, mean_time = %f\n", 
+				min_write_tim, max_write_tim, ave_write_tim);
+			printf("# Read:  min_time = %f, max_time = %f, mean_time = %f\n", 
+				min_read_tim, max_read_tim, ave_read_tim);
+		
+	   printf("Write bandwidth = %f Mbytes/sec\n", write_bw);
+	   printf("Read bandwidth = %f Mbytes/sec\n", read_bw);
+		
+		if (opt_correct) {
+			printf("Correctness test %s.\n", correct ? "passed" : "failed");
+		}
+	}
+
+
+die_jar_jar_die:	
+
+#if H5_HAVE_SETENV
+/* no setenv or unsetenv */
+	/* clear the environment variable if it was set earlier */
+	if	(opt_pvfstab_set){
+		unsetenv("PVFSTAB_FILE");
+	}
+#endif
+	
+	free(tmp);
+	if (opt_correct) free(tmp2);
+	MPI_Finalize();
+	return(0);
+}
+
+/* Wtime() - returns current time in sec., in a double */
+double Wtime()
+{
+	struct timeval t;
+	
+	gettimeofday(&t, NULL);
+	return((double)t.tv_sec + (double)t.tv_usec / 1000000);
+}
+
+#endif 	/* OLDSTUFF */
+
+#else /* H5_HAVE_PARALLEL */
+/* dummy program since H5_HAVE_PARALLE is not configured in */
+int
+main()
+{
+printf("No parallel IO performance because parallel is not configured in\n");
+return(0);
+}
+#endif /* H5_HAVE_PARALLEL */