在MPI中从结构类型创建新的驱动器数据类型？

Question

我正在为MPI创建新的派生数据类型以从Counter结构发送数据,你知道在MPI中创建新类型是痛苦和棘手的,因为如果我在正确的轨道上我需要一些帮助并且谢谢你？

typedef struct Counter{
int range1,range2,range3,range4;
double preset1 ,preset2 ,preset3 ,preset4;
}  countType;

MPI_Datatype createRecType()
{
    // Set-up the arguments for the type constructor
    MPI_Datatype new_type;
    int count = 2;

    int blocklens[] = { 4, 4 };
    MPI_Aint indices[4];
    indices[0] = 0;
     MPI_Type_extent( MPI_DOUBLE, &indices[1] );
     indices[1] *= 4;    // There are 2 doubles
    MPI_Datatype old_types[] = { MPI_INT ,MPI_DOUBLE};
        // Call the data type constructor
    MPI_Type_struct(count, blocklens, indices, old_types, &new_type);
    MPI_Type_commit(&new_type);

    return new_type;
}

Answer 1

如果我猜对了,请参阅https://computing.llnl.gov/tutorials/mpi/#Derived_Data_Types和"示例:Struct Derived Data Type"部分.它介绍了如何描述定义为"粒子":

typedef struct {
   float x, y, z;
   float velocity;
   int  n, type;
} Particle;

这样MPI就可以处理它们的数组.整个相关片段是:

/* Setup description of the 4 MPI_FLOAT fields x, y, z, velocity */
offsets[0] = 0;
oldtypes[0] = MPI_FLOAT;
blockcounts[0] = 4;

/* Setup description of the 2 MPI_INT fields n, type */
/* Need to first figure offset by getting size of MPI_FLOAT */
MPI_Type_extent(MPI_FLOAT, &extent);
offsets[1] = 4 * extent;
oldtypes[1] = MPI_INT;
blockcounts[1] = 2;

/* Now define structured type and commit it */
MPI_Type_struct(2, blockcounts, offsets, oldtypes, &particletype);
MPI_Type_commit(&particletype);

您的代码似乎遵循所有这些.除非你有一些拼写错误,否则你的代码似乎没问题.但我不能保证它,除非我尝试编译并运行它;)

有一点可以肯定,你indices太大了.[2]就足够了.但是把它放大不会有任何坏处.该count说2,所以MPI将无法读取该数组这些额外的元素.