[英]How to use MPI_Irecv?
From OpenMPI docs: C++ syntax 来自OpenMPI文档:C ++语法
Request Comm::Irecv(void* buf, int count, const Datatype&
datatype, int source, int tag) const
So I imagine I do something like: 所以我想我会做类似的事情:
MPI::Request req;
req = MPI_Irecv(&ballChallenges[i], 2, MPI_INT, i, TAG_AT_BALL, MPI_COMM_WORLD);
But it complains: 但它抱怨:
error: too few arguments to function ‘int MPI_Irecv(void*, int, MPI_Datatype, int, int, MPI_Comm, ompi_request_t**)’
Seems like I am missing ompi_request_t**
, but its not documented? 好像我缺少ompi_request_t**
,但是没有记录? Tried 试过了
MPI_Irecv(&ballChallenges[i], 2, MPI_INT, i, TAG_AT_BALL, MPI_COMM_WORLD, &req);
But fails with 但是失败了
error: cannot convert ‘MPI::Request*’ to ‘ompi_request_t**’ for argument ‘7’ to ‘int MPI_Irecv(void*, int, MPI_Datatype, int, int, MPI_Comm, ompi_request_t**)’
So whats with the ompi_request_t
part? 那么ompi_request_t
部分又如何呢?
This works (C): 这有效(C):
#include <stdio.h>
#include <string.h>
#include <mpi.h>
int main(int argc, char **argv) {
int rank;
const char *msg="Hello!";
const int len=strlen(msg)+1;
char buf[len];
MPI_Request isreq, irreq;
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
if (rank == 0) {
MPI_Isend((void*)msg, len, MPI_CHAR, 0, 0, MPI_COMM_WORLD, &isreq);
MPI_Irecv(buf, len, MPI_CHAR, 0, 0, MPI_COMM_WORLD, &irreq);
MPI_Cancel(&irreq);
MPI_Cancel(&isreq);
}
MPI_Finalize();
return 0;
}
Or this works (C++) 还是行得通(C ++)
#include <cstring>
#include <mpi.h>
using namespace MPI;
int main(int argc, char **argv) {
const char *msg="Hello!";
const int len=strlen(msg)+1;
char *buf = new char[len];
Init(argc, argv);
int rank = COMM_WORLD.Get_rank();
if (rank == 0) {
Request isreq = COMM_WORLD.Isend(msg, len, MPI_CHAR, 0, 0);
Request irreq = COMM_WORLD.Irecv(buf, len, MPI_CHAR, 0, 0);
isreq.Cancel();
irreq.Cancel();
}
Finalize();
return 0;
}
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