C 使用MPI IO读取文件时的值错误

下面是一个简单的

C

程序，它与

MPI IO

并行读取文件：

#include <stdio.h>
#include <stdlib.h>

#include "mpi.h"

#define N 10

main( int argc, char **argv )
{
    int rank, size;
    MPI_Init(&argc, &argv);
    MPI_Comm_rank( MPI_COMM_WORLD, &rank );
    MPI_Comm_size( MPI_COMM_WORLD, &size );

    int i0 = N *  rank / size;
    int i1 = N * (rank+1) / size;
    printf("rank: %d, i0: %d, i1: %d\n", rank, i0, i1);

    int i;
    double* data = malloc( (i1-i0)*sizeof(double) );
    for (i = 0 ; i < i1-i0 ; i++)
        data[i] = 123.;

    MPI_File f;
    MPI_File_open(MPI_COMM_WORLD, "data.bin", MPI_MODE_RDONLY, 
                  MPI_INFO_NULL, &f);

    MPI_File_set_view(f, i0, MPI_DOUBLE, MPI_DOUBLE, "native",
                      MPI_INFO_NULL);

    MPI_Status status;
    MPI_File_read(f, data, i1-i0, MPI_DOUBLE, &status);

    int count;
    MPI_Get_count(&status, MPI_DOUBLE, &count);
    printf("rank %d, %d value read\n", rank, count);

    for (i = 0 ; i < i1-i0 ; i++) {
        printf("rank: %d index: %d value: %.2f\n", rank, i, data[i]);
    }

    MPI_File_close(&f);

    MPI_Finalize();

    free(data);

    return 0;
}

读取的值正确：

rank: 0, i0: 0, i1: 10
rank 0, 10 value read
rank: 0 index: 0 value: 0.00
rank: 0 index: 1 value: 1.00
rank: 0 index: 2 value: 2.00
rank: 0 index: 3 value: 3.00
rank: 0 index: 4 value: 4.00
rank: 0 index: 5 value: 5.00
rank: 0 index: 6 value: 6.00
rank: 0 index: 7 value: 7.00
rank: 0 index: 8 value: 8.00
rank: 0 index: 9 value: 9.00

但有两个过程：

./read_mpi_io

mpirun -n 2 ./read_mpi_io

我得到了错误的值（零）：

---

我的C代码出了什么问题？

调用

MPI\u File\u set\u view（）。因此，这里需要将
i0
参数乘以要读取的元素的大小，即
sizeof（double）

将相应的行替换为：

MPI_File_set_view( f, i0 * sizeof( double ), MPI_DOUBLE, MPI_DOUBLE,
                   "native", MPI_INFO_NULL );

只需解决问题并使代码按预期工作。
谢谢，这就是错误所在！
MPI_File_set_view( f, i0 * sizeof( double ), MPI_DOUBLE, MPI_DOUBLE,
                   "native", MPI_INFO_NULL );