On 12/5/2010 7:13 PM, 孟宪军 wrote:
hi,
I met a question recently when I tested the MPI_send and MPI_Recv
functions. When I run the following codes, the processes hanged and I
found there was not data transmission in my network at all.
BTW: I finished this test on two X86-64 computers with 16GB memory and
installed Linux.
1 #include <stdio.h>
2 #include <mpi.h>
3 #include <stdlib.h>
4 #include <unistd.h>
5
6
7 int main(int argc, char** argv)
8 {
9 int localID;
10 int numOfPros;
11 size_t Gsize = (size_t)2 * 1024 * 1024 * 1024;
12
13 char* g = (char*)malloc(Gsize);
14
15 MPI_Init(&argc, &argv);
16 MPI_Comm_size(MPI_COMM_WORLD, &numOfPros);
17 MPI_Comm_rank(MPI_COMM_WORLD, &localID);
18
19 MPI_Datatype MPI_Type_lkchar;
20 MPI_Type_contiguous(2048, MPI_BYTE, &MPI_Type_lkchar);
21 MPI_Type_commit(&MPI_Type_lkchar);
22
23 if (localID == 0)
24 {
25 MPI_Send(g, 1024*1024, MPI_Type_lkchar, 1, 1, MPI_COMM_WORLD);
26 }
27
28 if (localID != 0)
29 {
30 MPI_Status status;
31 MPI_Recv(g, 1024*1024, MPI_Type_lkchar, 0, 1, \
32 MPI_COMM_WORLD, &status);
33 }
34
35 MPI_Finalize();
36
37 return 0;
38 }
You supplied all your constants as 32-bit signed data, so, even if the
count for MPI_Send() and MPI_Recv() were a larger data type, you would
see this limit. Did you look at your <mpi.h> ?
--
Tim Prince
