/* parallel MPI write to a single file */

#include "mpi.h"
#include <stdio.h>
#include <string.h>

#define D      3             /* dimensions */

#define X   256             /* global x grid size */
#define Y   256             /* global y grid size */
#define Z   256             /* global z grid size */

#define nx   128             /* local x grid size */
#define ny   128             /* local y grid size */
#define nz   128             /* local z grid size */

#define ng (nx*ny*nz)        /* local grid (cube) size */

#define npx    2             /* number of PE's in x direction */
#define npy    2             /* number of PE's in y direction */
#define npz    2             /* number of PE's in z direction */

#define np (npx*npy*npz)  /* total PE count */

#define LOOP 1

#define MAX_RR_NAME 7

int
main(int argc, char* argv[])
{
    int  i, rank, npes, bug=0;
    int buf[ng];
    MPI_File     thefile;
    MPI_Status   status;
    MPI_Datatype filetype;
    MPI_Comm     new_comm;
    MPI_Offset   offset=0;
    MPI_Info     info=MPI_INFO_NULL;
    int gsize[D],distrib[D],dargs[D],psize[D];
    int dims[D],periods[D],reorder;
    double t1,t2,mbs;
    double to1,to2,tc1,tc2;
    double et,eto,etc;
    double max_mbs,min_mbs,avg_mbs;
    double max_et,min_et,avg_et;
    double max_eto,min_eto,avg_eto;
    double max_etc,min_etc,avg_etc;
    char process_name[MPI_MAX_PROCESSOR_NAME + 1];
    char rr_blank[] = {"       "};
    char rr_empty[] = {"???????"};
    int  count;
    
    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &npes);
    if ( rank == 0 )
    {
        if ( argc < 2 )
        {
            printf(" ERROR: no filename given\n");
            bug++;
        }
        if ( npes == np )
        {
            printf(" file name: %s\n",argv[1]);
            printf(" total number of PE's: %3d\n",np);
            printf(" number of PE's in x direction: %4d\n",npx);
            printf(" number of PE's in y direction: %4d\n",npy);
            printf(" number of PE's in z direction: %4d\n",npz);
            printf(" global grid size: %dx%dx%d 4 byte integers (total %lu)\n",X,Y,Z,(unsigned long)X*Y*Z);
            printf("  local grid size: %dx%dx%d 4 byte integers (total %d)\n",nx,ny,nz,ng);
        }
        else
        {
            printf(" ERROR: total number of PE's must be %d\n",np);
            printf("        actual number of PE's was %d\n",npes);
            bug++;
        }
        if ( bug )
        {
            MPI_Abort(MPI_COMM_WORLD,-1);
        }
    }
    if ( MPI_Get_processor_name(process_name, &count) != MPI_SUCCESS)
    {
        sprintf(process_name, "%s", rr_empty);
    }
    else
    {
        if (count < MAX_RR_NAME) strncat(&process_name[count],rr_blank,MAX_RR_NAME-count);
        process_name[MAX_RR_NAME] = '\0';
    }
    
    MPI_Barrier(MPI_COMM_WORLD);
    
    MPI_Info_create(&info);
    
    /* allow multiple writers to write to the file concurrently */
    
    /*MPI_Info_set(info,"panfs_concurrent_write","1");*/
    
    /* use data aggregation */
    
    /*MPI_Info_set(info,"romio_cb_write","enable"); */
    /*MPI_Info_set(info,"romio_cb_write","disable");*/
    /*MPI_Info_set(info,"romio_cb_read","enable"); */
    /*MPI_Info_set(info,"romio_cb_read","disable");*/
    
    /* use one aggregator/writer per node */
    
    /*MPI_Info_set(info,"cb_config_list","*:1");*/
    
    /* aggregators/writers per allocation: use this or the above (both work) */
    
    /*i = ((npes-1)/8) + 1;
     sprintf(awpa,"%d",i);
     MPI_Info_set (info,"cb_nodes",awpa);*/
    
    
    for ( i=0; i<ng; i++ ) buf[i] = rank*10000 + (i+1)%1024;
    
    for ( i=0; i<D; i++ )
    {
        periods[i] = 1;  /* true */
    }
    
    reorder = 1;        /* true */
    
    dims[0] = npx;
    dims[1] = npy;
    dims[2] = npz;
    
    MPI_Cart_create(MPI_COMM_WORLD, D, dims, periods, reorder, &new_comm);
    
    for ( i=0; i<D; i++ )
    {
        distrib[i] = MPI_DISTRIBUTE_BLOCK;
        dargs[i]   = MPI_DISTRIBUTE_DFLT_DARG;
        /*   psize[i]   = 0; */
    }
    
    gsize[0] = X;
    gsize[1] = Y;
    gsize[2] = Z;
    
    psize[0] = npx;
    psize[1] = npy;
    psize[2] = npz;
    
    /*
     MPI_Dims_create(npes, D, psize);  
     
     printf("psize %d %d %d\n",psize[0],psize[1],psize[2]);
     */
    
    MPI_Type_create_darray(npes, rank, D, gsize, distrib, dargs, psize, MPI_ORDER_FORTRAN, MPI_INT, &filetype);
    /*MPI_Type_create_darray(npes, rank, D, gsize, distrib, dargs, psize, MPI_ORDER_C, MPI_INT, &filetype);              don't do this */
    
    MPI_Type_commit(&filetype);
    
    to1 = MPI_Wtime();
    MPI_File_open(new_comm, argv[1], MPI_MODE_WRONLY | MPI_MODE_CREATE, info, &thefile);
    to2 = MPI_Wtime();
    
    MPI_File_set_size(thefile, offset);
    
    MPI_File_set_view(thefile, offset, MPI_INT, filetype, "native", MPI_INFO_NULL);
    
    t1 = MPI_Wtime();
    for ( i=0; i<LOOP; i++)
    {
        MPI_File_write_all(thefile, buf, ng, MPI_INT, &status);
    }
    t2 = MPI_Wtime();
    
    tc1 = MPI_Wtime();
    MPI_File_close(&thefile);
    tc2 = MPI_Wtime();
    
    et  = (t2  - t1)/LOOP;
    eto = (to2 - to1)/LOOP;
    etc = (tc2 - tc1)/LOOP;
    
    mbs = (((double)(LOOP*X*Y*Z)*sizeof(int)))/(1000000.0*(t2-t1));
    
    /*printf(" %s[%3d]    ET  %8.2f  %8.2f  %8.2f         %8.1f mbs\n", process_name, rank, t1, t2, t2-t1, mbs);*/
    
    MPI_Barrier(MPI_COMM_WORLD);
    
    MPI_Reduce(&mbs, &avg_mbs, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
    MPI_Reduce(&mbs, &min_mbs, 1, MPI_DOUBLE, MPI_MIN, 0, MPI_COMM_WORLD);
    MPI_Reduce(&mbs, &max_mbs, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
    
    MPI_Reduce(&et, &avg_et, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
    MPI_Reduce(&et, &min_et, 1, MPI_DOUBLE, MPI_MIN, 0, MPI_COMM_WORLD);
    MPI_Reduce(&et, &max_et, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
    
    MPI_Reduce(&eto, &avg_eto, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
    MPI_Reduce(&eto, &min_eto, 1, MPI_DOUBLE, MPI_MIN, 0, MPI_COMM_WORLD);
    MPI_Reduce(&eto, &max_eto, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
    
    MPI_Reduce(&etc, &avg_etc, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
    MPI_Reduce(&etc, &min_etc, 1, MPI_DOUBLE, MPI_MIN, 0, MPI_COMM_WORLD);
    MPI_Reduce(&etc, &max_etc, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
    
    fflush(stdout);
    
    if ( rank == 0 )
    {
        mbs = avg_mbs/npes;
        printf("\n     average write rate: %9.1f mbs\n", mbs);
        printf("     minimum write rate: %9.1f mbs\n", min_mbs);
        printf("     maximum write rate: %9.1f mbs\n\n", max_mbs);
        avg_eto = avg_eto/npes;
        avg_et  = avg_et/npes;
        avg_etc = avg_etc/npes;
        printf("     open time:  %9.3f min %9.3f avg %9.3f max\n",min_eto,avg_eto,max_eto);  
        printf("     write time: %9.3f min %9.3f avg %9.3f max\n",min_et,avg_et,max_et);  
        printf("     close time: %9.3f min %9.3f avg %9.3f max\n\n",min_etc,avg_etc,max_etc);  
        fflush(stdout);
    }
    
    MPI_Finalize();
    
    return 0;
}