C语言 使用mpi的矩阵乘法中的分割错误

Question

我想写一个mpi程序2矩阵的乘法。如果我给矩阵的大小低于800的代码工作，但当我给它更高，我得到分割错误，我无法找出原因。我是MPI的新手，所以还在努力理解一切。如果可能的话，请帮忙。

#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>
#define N 1000
int 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);
double a[N][N], b[N][N], c[N][N];
int i, j, k;
// Initialize the matrices with random values
if (rank == 0) {
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
a[i][j] = (double)rand() / RAND_MAX;
b[i][j] = (double)rand() / RAND_MAX;
}
}
}
// Broadcast the matrices to all ranks
MPI_Bcast(a, N*N, MPI_DOUBLE, 0, MPI_COMM_WORLD);
MPI_Bcast(b, N*N, MPI_DOUBLE, 0, MPI_COMM_WORLD);
// Each rank calculates a portion of the output matrix
int rows_per_rank = N / size;
int start_row = rows_per_rank * rank;
int end_row = start_row + rows_per_rank;
for (i = start_row; i < end_row; i++) {
for (j = 0; j < N; j++) {
c[i][j] = 0;
for (k = 0; k < N; k++) {
c[i][j] += a[i][k] * b[k][j];
}
}
}
// Gather the output matrix from all ranks
double* c_buffer = (double*) malloc(N*N*sizeof(double));
MPI_Gather(c, rows_per_rank*N, MPI_DOUBLE, c_buffer, rows_per_rank*N, MPI_DOUBLE, 0, MPI_COMM_WORLD);
// Print the output matrix
if (rank == 0) {
printf("Output matrix C:n");
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
printf("%lf ", c_buffer[i*N + j]);
}
printf("n");
}
}
free(c_buffer);
MPI_Finalize();
return 0;
}

Answer 1

这一行

double a[N][N], b[N][N], c[N][N];

N = 1000的需要24mb的堆栈空间。这几乎肯定比现有的要大。要么静态地分配它们(将kwstatic放在它们之前)，要么在堆上动态地分配它们