最后搜索和搜索后,我有了为向量或线性等nD数组分配内存的功能 功能是:
int malloc2dint(int ***array, int n, int m)
{
/* allocate the n*m contiguous items */
int *p = (int *)malloc(n*m*sizeof(int));
if (!p) return -1;
/* allocate the row pointers into the memory */
(*array) = (int **)malloc(n*sizeof(int*));
if (!(*array))
{
free(p);
return -1;
}
/* set up the pointers into the contiguous memory */
int i;
for (i=0; i<n; i++)
(*array)[i] = &(p[i*m]);
return 0;
}
通过使用此方法,我可以正确地广播并分散2d动态分配的数组,但MPI_Gather
中的问题仍然存在。
主要功能是:
int length = atoi(argv[1]);
int rank, size, from, to, i, j, k, **first_array, **second_array, **result_array;
MPI_Init (&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
//2D dynamic memory allocation
malloc2dint(&first_array, length, length);
malloc2dint(&second_array, length, length);
malloc2dint(&result_array, length, length);
//Related boundary to each task
from = rank * length/size;
to = (rank+1) * length/size;
//Intializing first and second array
if (rank==0)
{
for(i=0; i<length; i++)
for(j=0; j<length; j++)
{
first_array[i][j] = 1;
second_array[i][j] = 1;
}
}
//Broadcast second array so all tasks will have it
MPI_Bcast (&(second_array[0][0]), length*length, MPI_INT, 0, MPI_COMM_WORLD);
//Scatter first array so each task has matrix values between its boundary
MPI_Scatter (&(first_array[0][0]), length*(length/size), MPI_INT, first_array[from], length*(length/size), MPI_INT, 0, MPI_COMM_WORLD);
//Now each task will calculate matrix multiplication for its part
for (i=from; i<to; i++)
for (j=0; j<length; j++)
{
result_array[i][j]=0;
for (k=0; k<length; k++)
result_array[i][j] += first_array[i][k]*second_array[k][j];
//printf("\nrank(%d)->result_array[%d][%d] = %d\n", rank, i, j, result_array[i][j]);
//this line print the correct value
}
//Gathering info from all task and put each partition to resulat_array
MPI_Gather (&(result_array[from]), length*(length/size), MPI_INT, result_array, length*(length/size), MPI_INT, 0, MPI_COMM_WORLD);
if (rank==0)
{
for (i=0; i<length; i++)
{
printf("\n\t| ");
for (j=0; j<length; j++)
printf("%2d ", result_array[i][j]);
printf("|\n");
}
}
MPI_Finalize();
return 0;
现在,当我运行mpirun -np 2 xxx.out 4
时,输出为:
| 4 4 4 4 | ---> Good Job!
| 4 4 4 4 | ---> Good Job!
| 1919252078 1852795251 1868524912 778400882 | ---> Where are you baby?!!!
| 540700531 1701080693 1701734758 2037588068 | ---> Where are you baby?!!!
最后,mpirun注意到进程rank 0
已退出信号6(已中止)
对我而言,奇怪的一点是MPI_Bcast
和MPI_Scatter
工作正常但MPI_Gather
没有
任何帮助将高度赞赏
答案 0 :(得分:1)
问题在于如何传递缓冲区。您在MPI_Scatter
中正确执行了该操作,但对MPI_Gather
进行了错误的操作。
将result_array
作为通过&result_array[from]
传递将读取保存指针列表的内存而不是矩阵的实际数据。请改用&result_array[from][0]
。
同样适用于接收缓冲区。通过&result_array[0][0]
而不是result_array
来传递指向数据位于内存中的位置的指针。
因此,而不是:
//Gathering info from all task and put each partition to resulat_array
MPI_Gather (&(result_array[from]), length*(length/size), MPI_INT, result_array, length*(length/size), MPI_INT, 0, MPI_COMM_WORLD);
执行:
//Gathering info from all task and put each partition to resulat_array
MPI_Gather (&(result_array[from][0]), length*(length/size), MPI_INT, &(result_array[0][0]), length*(length/size), MPI_INT, 0, MPI_COMM_WORLD);