使用 MPI_Send 和 MPI_Recv 实施 MPI_Scatter 时出现问题
Problems implementing MPI_Scatter with MPI_Send and MPI_Recv
我正在尝试使用 MPI_Send 和 MPI_Recv 实现 MPI 函数 MPI_Scatter。
我想使用函数的官方声明,它使用 vectors/arrays 的指针。
MPI_Scatter(
void* send_data,
int send_count,
MPI_Datatype send_datatype,
void* recv_data,
int recv_count,
MPI_Datatype recv_datatype,
int root,
MPI_Comm communicator)
我创建了一个非常适合 MPI MPI_Scatter 的示例。它显示了正确的结果。
我必须函数来实现这些东西,一个是指针,一个是静态整数数组。第二个工作正常,但第一个只显示创建的数组的前三个元素。我认为这是与矩阵的分配内存有关的问题,但我看不到解决它的方法。
这是代码(MMPI_Scatter 让我出错):
#include <stdio.h>
#include <mpi.h>
#include <stdlib.h>
#include <math.h>
#include <unistd.h>
#define ROOT 0
#define N 3
int main(int argc, char **argv) {
// for storing this process' rank, and the number of processes
int rank, np;
int *matrix;
//MPI_Scatter
int send_count, recv_count;
int *recv_data;
MPI_Status status, info;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD,&np);
MPI_Comm_rank(MPI_COMM_WORLD,&rank);
if (rank == ROOT) {
matrix = createMatrix(np, np);
printArray(matrix, np * np);
}
send_count = np;
recv_count = np;
recv_data = malloc(recv_count * sizeof(int));
//The original function provided by MPI works great!!
MPI_Scatter(matrix, send_count, MPI_INT, recv_data, recv_count, MPI_INT, ROOT, MPI_COMM_WORLD);
//This function just show the first three elements of the matrix
//MMPI_Scatter(matrix, send_count, MPI_INT, recv_data, recv_count, MPI_INT, ROOT, MPI_COMM_WORLD);
//This function works great, but it not use the official declaration of the MPI_Scatter
//MMPI_Scatter2(matrix, send_count, MPI_INT, recv_data, recv_count, MPI_INT, ROOT, MPI_COMM_WORLD);
printArray(recv_data , recv_count);
MPI_Finalize();
return 0;
}
//http://mpitutorial.com/tutorials/mpi-scatter-gather-and-allgather/
void MMPI_Scatter(void* send_data, int send_count, MPI_Datatype send_datatype,
void* recv_data, int recv_count, MPI_Datatype recv_datatype,
int root, MPI_Comm communicator) {
int np, rank;
int i;
MPI_Status status;
MPI_Comm_size(communicator, &np);
MPI_Comm_rank(communicator, &rank);
printArray(send_data, np * np);
if (rank == ROOT) {
for (i = 0; i < np; i++) {
MPI_Send(send_data + (i * send_count), send_count, send_datatype, i, 0, communicator);
}
}
MPI_Recv(recv_data, recv_count, recv_datatype, root, 0, communicator, &status);
printArray(send_data, np * np);
}
//Works great, but without pointer
void MMPI_Scatter2(int send_data[], int send_count, MPI_Datatype send_datatype,
int recv_data[], int recv_count, MPI_Datatype recv_datatype,
int root, MPI_Comm communicator) {
int np, rank;
int i;
MPI_Status status;
MPI_Comm_size(communicator, &np);
MPI_Comm_rank(communicator, &rank);
if (rank == ROOT) {
for (i = 0; i < np; i++) {
MPI_Send(send_data + (i * send_count), send_count, send_datatype, i, 0, communicator);
}
}
MPI_Recv(recv_data, recv_count, recv_datatype, root, 0, communicator, &status);
printArray(recv_data, np);
}
int *createMatrix(int nRows, int nCols) {
int *matrix;
int h, i, j;
if ((matrix = malloc(nRows * nCols * sizeof(int))) == NULL) {
printf("Malloc error:");
exit(1);
}
//Test values
for (h = 0; h < nRows * nCols; h++) {
matrix[h] = h + 1;
}
return matrix;
}
更新 1:
我认为它与此 link 中的信息有关:
https://www.mpi-forum.org/docs/mpi-1.1/mpi-11-html/node71.html#Node71
有一行:
MPI_Send(sendbuf + i*sendcount*extent(sendtype), sendcount, sendtype, i.....)
但我不知道如何处理 extend(sendtype)
更新 2:
现在可以了,但目前因为我自己知道数据类型
void MMPI_Scatter(void* send_data, int send_count, MPI_Datatype send_datatype,
void* recv_data, int recv_count, MPI_Datatype recv_datatype,
int root, MPI_Comm communicator) {
int np, rank;
int i;
int size;
MPI_Datatype type;
type = MPI_INT;
MPI_Type_size(type, &size);
MPI_Status status;
MPI_Comm_size(communicator, &np);
MPI_Comm_rank(communicator, &rank);
if (rank == ROOT) {
for (i = 0; i < np; i++) {
MPI_Send(send_data + ((i * send_count) * size), send_count, send_datatype, i, 0, communicator);
}
}
MPI_Recv(recv_data, recv_count, recv_datatype, root, 0, communicator, &status);
}
更新 3(已解决):
void MMPI_Scatter(void* send_data, int send_count, MPI_Datatype send_datatype,
void* recv_data, int recv_count, MPI_Datatype recv_datatype,
int root, MPI_Comm communicator) {
int np, rank;
int i;
int size;
MPI_Datatype type;
type = send_datatype;
MPI_Type_size(type, &size);
MPI_Status status;
MPI_Comm_size(communicator, &np);
MPI_Comm_rank(communicator, &rank);
if (rank == ROOT) {
for (i = 0; i < np; i++) {
MPI_Send(send_data + ((i * send_count) * size), send_count, send_datatype, i, 0, communicator);
}
}
MPI_Recv(recv_data, recv_count, recv_datatype, root, 0, communicator, &status);
}
更新 4
这个函数工作正常,因为使用了ROOT,但是一旦从集体调用,ROOT必须被root替换,如下所示:
if (rank == root) {
}
将send_data + (i * send_count)
更改为:
send_data + (i * send_count + MPI_Type_size(send_datatype)
我正在尝试使用 MPI_Send 和 MPI_Recv 实现 MPI 函数 MPI_Scatter。
我想使用函数的官方声明,它使用 vectors/arrays 的指针。
MPI_Scatter(
void* send_data,
int send_count,
MPI_Datatype send_datatype,
void* recv_data,
int recv_count,
MPI_Datatype recv_datatype,
int root,
MPI_Comm communicator)
我创建了一个非常适合 MPI MPI_Scatter 的示例。它显示了正确的结果。
我必须函数来实现这些东西,一个是指针,一个是静态整数数组。第二个工作正常,但第一个只显示创建的数组的前三个元素。我认为这是与矩阵的分配内存有关的问题,但我看不到解决它的方法。
这是代码(MMPI_Scatter 让我出错):
#include <stdio.h>
#include <mpi.h>
#include <stdlib.h>
#include <math.h>
#include <unistd.h>
#define ROOT 0
#define N 3
int main(int argc, char **argv) {
// for storing this process' rank, and the number of processes
int rank, np;
int *matrix;
//MPI_Scatter
int send_count, recv_count;
int *recv_data;
MPI_Status status, info;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD,&np);
MPI_Comm_rank(MPI_COMM_WORLD,&rank);
if (rank == ROOT) {
matrix = createMatrix(np, np);
printArray(matrix, np * np);
}
send_count = np;
recv_count = np;
recv_data = malloc(recv_count * sizeof(int));
//The original function provided by MPI works great!!
MPI_Scatter(matrix, send_count, MPI_INT, recv_data, recv_count, MPI_INT, ROOT, MPI_COMM_WORLD);
//This function just show the first three elements of the matrix
//MMPI_Scatter(matrix, send_count, MPI_INT, recv_data, recv_count, MPI_INT, ROOT, MPI_COMM_WORLD);
//This function works great, but it not use the official declaration of the MPI_Scatter
//MMPI_Scatter2(matrix, send_count, MPI_INT, recv_data, recv_count, MPI_INT, ROOT, MPI_COMM_WORLD);
printArray(recv_data , recv_count);
MPI_Finalize();
return 0;
}
//http://mpitutorial.com/tutorials/mpi-scatter-gather-and-allgather/
void MMPI_Scatter(void* send_data, int send_count, MPI_Datatype send_datatype,
void* recv_data, int recv_count, MPI_Datatype recv_datatype,
int root, MPI_Comm communicator) {
int np, rank;
int i;
MPI_Status status;
MPI_Comm_size(communicator, &np);
MPI_Comm_rank(communicator, &rank);
printArray(send_data, np * np);
if (rank == ROOT) {
for (i = 0; i < np; i++) {
MPI_Send(send_data + (i * send_count), send_count, send_datatype, i, 0, communicator);
}
}
MPI_Recv(recv_data, recv_count, recv_datatype, root, 0, communicator, &status);
printArray(send_data, np * np);
}
//Works great, but without pointer
void MMPI_Scatter2(int send_data[], int send_count, MPI_Datatype send_datatype,
int recv_data[], int recv_count, MPI_Datatype recv_datatype,
int root, MPI_Comm communicator) {
int np, rank;
int i;
MPI_Status status;
MPI_Comm_size(communicator, &np);
MPI_Comm_rank(communicator, &rank);
if (rank == ROOT) {
for (i = 0; i < np; i++) {
MPI_Send(send_data + (i * send_count), send_count, send_datatype, i, 0, communicator);
}
}
MPI_Recv(recv_data, recv_count, recv_datatype, root, 0, communicator, &status);
printArray(recv_data, np);
}
int *createMatrix(int nRows, int nCols) {
int *matrix;
int h, i, j;
if ((matrix = malloc(nRows * nCols * sizeof(int))) == NULL) {
printf("Malloc error:");
exit(1);
}
//Test values
for (h = 0; h < nRows * nCols; h++) {
matrix[h] = h + 1;
}
return matrix;
}
更新 1:
我认为它与此 link 中的信息有关: https://www.mpi-forum.org/docs/mpi-1.1/mpi-11-html/node71.html#Node71
有一行:
MPI_Send(sendbuf + i*sendcount*extent(sendtype), sendcount, sendtype, i.....)
但我不知道如何处理 extend(sendtype)
更新 2:
现在可以了,但目前因为我自己知道数据类型
void MMPI_Scatter(void* send_data, int send_count, MPI_Datatype send_datatype,
void* recv_data, int recv_count, MPI_Datatype recv_datatype,
int root, MPI_Comm communicator) {
int np, rank;
int i;
int size;
MPI_Datatype type;
type = MPI_INT;
MPI_Type_size(type, &size);
MPI_Status status;
MPI_Comm_size(communicator, &np);
MPI_Comm_rank(communicator, &rank);
if (rank == ROOT) {
for (i = 0; i < np; i++) {
MPI_Send(send_data + ((i * send_count) * size), send_count, send_datatype, i, 0, communicator);
}
}
MPI_Recv(recv_data, recv_count, recv_datatype, root, 0, communicator, &status);
}
更新 3(已解决):
void MMPI_Scatter(void* send_data, int send_count, MPI_Datatype send_datatype,
void* recv_data, int recv_count, MPI_Datatype recv_datatype,
int root, MPI_Comm communicator) {
int np, rank;
int i;
int size;
MPI_Datatype type;
type = send_datatype;
MPI_Type_size(type, &size);
MPI_Status status;
MPI_Comm_size(communicator, &np);
MPI_Comm_rank(communicator, &rank);
if (rank == ROOT) {
for (i = 0; i < np; i++) {
MPI_Send(send_data + ((i * send_count) * size), send_count, send_datatype, i, 0, communicator);
}
}
MPI_Recv(recv_data, recv_count, recv_datatype, root, 0, communicator, &status);
}
更新 4
这个函数工作正常,因为使用了ROOT,但是一旦从集体调用,ROOT必须被root替换,如下所示:
if (rank == root) {
}
将send_data + (i * send_count)
更改为:
send_data + (i * send_count + MPI_Type_size(send_datatype)