MPI_Gather中的一系列结构

Question

我正在尝试使用MPI_Gather收集一组结构。我通过使用MPI_Type_contiguous（每个元素是一个double）创建了一个结构“Final”的派生数据类型“mystruct”。然后我在一个简单的MPI_Send和MPI_Receive中使用这个派生数据类型来检查它是否正确并且它可以工作。现在，我想使用MPI_Gather来收集整个结构数组，每个结构数组都有派生数据类型“mystruct”。

使用Send和Recv，我知道MPI_Type_contiguous部分是正确的。在MPI_Gather之后，MASTER只会在应该从子进程收集信息的位置打印出元素的零。

typedef struct{
        double Angle;
        double E_ODD;
        double OD_KE;
        double OD_L;
        double D_E;
}Final;

int main(int argc, char** argv)
{
ierr = MPI_Init(&argc,&argv);
ierr = MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
ierr = MPI_Comm_rank(MPI_COMM_WORLD,&taskid);

int totalnum_trajectories = file_size/9 //File that has xyz cartesian
                                        //coordinates for three atoms

int localnum_trajectories = totalnum_trajectories/numprocs;


Final worker_results[localnum_trajectory];
//Each processor does some analysis for its local number of trajectories
//and results go into worker_results buffer for each trajectory. 

//Create a datatype for the nth worker_results[n] struct
MPI_Datatype mystruct;
MPI_Type_contiguous(5,MPI_DOUBLE,&mystruct);
MPI_Type_commit(&mystruct);

//MASTER buffer: should get all local struct arrays from 
//children processors to one larger array of structs, equaling 
//the total number of trajectories
Final master_results[totalnum_trajectories];

ierr = MPI_Gather(worker_results, localnum_trajectory, mystruct, \
                  master_results, totalnum_trajectories, \
                  mystruct, MASTER, MPI_COMM_World);

//Do some I/O with MASTER; everything should be in master_results buffer

MPI_Finalize();
return(0);
}

在正确的MPI_Gather之后，MASTER应该为所有子项提供适当的I / O结果。

Answer 1

我想到了。正如评论所暗示的那样，MASTER的接收计数应该是每个处理器的项目数（所以localnum_trajectoires），而不是所有处理器的计数总数。所以一切都是正确的，除了MPI_Gather MASTER计数，应该是这样的

ierr = MPI_Gather(worker_results, localnum_trajectories, mystruct,\
                  master_results, localnum_trajectories, mystruct,\
                  MASTER, MPI_COMM_WORLD);

干杯！！！