Hi all,
I'm trying to write a trivial program of sending array elements from slave
nodes to root node.
The slave nodes create a portion of an array and try to send it to the root
node.
I wrote the following code where the slave nodes send start_pos, share and
nsareanode array to the root node.
For the example output shown below, I'm running on 3 nodes including root.
nsareanode is the required
partial array calculated in each node and transferred to the root node to
put in another matrix nsarea[][]. For this example,
the total array length is 30 and I'm splitting the computation into 3..with
ten elements (share) computed by each node.
if (rank!=0) {
// Send start_pos, share and nsareanode arrays to root node
MPI_Send(&start_pos,1,MPI_INT,0,1,MPI_COMM_WORLD);
MPI_Send(&share,1,MPI_INT,0,1,MPI_COMM_WORLD);
MPI_Send(nsareanode,share,MPI_FLOAT,0,1,MPI_COMM_WORLD);
fprintf(stderr,"Node %d sending stuff to Root\n",rank);
}
if (rank==0) {
for (tmprank=1;tmprank<psize;tmprank++) {
fprintf(stderr,"Root about to receive data from Node\n");
MPI_Recv(&start_pos,1,MPI_INT,MPI_ANY_SOURCE,MPI_ANY_TAG,MPI_COMM_WORLD,&status);
fprintf(stderr,"start_pos=%d\n",start_pos);
MPI_Recv(&share,1,MPI_INT,MPI_ANY_SOURCE,MPI_ANY_TAG,MPI_COMM_WORLD,&status);
fprintf(stderr,"source=%d\tstart_pos=%d\tshare=%d\n",status.MPI_SOURCE,start_pos,share);
MPI_Recv(nsareanode,share,MPI_FLOAT,MPI_ANY_SOURCE,1,MPI_COMM_WORLD,&status);
for (tmpint=start_pos;tmpint<start_pos+share;tmpint++) {
nsarea[jjj][tmpint] = nsareanode[tmpint-start_pos];
fprintf(stderr,"nsarea[%d][%d]=%f\n",jjj,tmpint,nsarea[jjj][tmpint]);
}
}
}
rank=2 share=10 start_pos=20
rank=1 share=10 start_pos=10
rank=0 share=10 start_pos=0
Root about to receive data from Node
start_pos=20
source=1 start_pos=20 share=10
nsarea[0][20]=0.000000
nsarea[0][21]=53.554237
nsarea[0][22]=55.088585
nsarea[0][23]=54.225426
nsarea[0][24]=58.777073
nsarea[0][25]=64.479797
nsarea[0][26]=70.079277
nsarea[0][27]=75.008041
nsarea[0][28]=77.893166
nsarea[0][29]=78.853493
Root about to receive data from Node
start_pos=10
Node 1 sending stuff to Root
MPI_Recv: message truncated (rank 0, MPI_COMM_WORLD)
Rank (0, MPI_COMM_WORLD): Call stack within LAM:
Rank (0, MPI_COMM_WORLD): - MPI_Recv()
Rank (0, MPI_COMM_WORLD): - main()
Node 2 sending stuff to Root
-----------------------------------------------------------------------------
One of the processes started by mpirun has exited with a nonzero exit
code. This typically indicates that the process finished in error.
If your process did not finish in error, be sure to include a "return
0" or "exit(0)" in your C code before exiting the application.
PID 13897 failed on node n1 with exit status 1.
It looks like, MPI_ANY_SOURCE is causing problems in the MPI_Recv
statement. Could someone tell me what exactly is going
on and how to implement this?
Thanks
Sriram
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Sriram K. Rallabhandi
Graduate Research Assistant Work: 404 385 2789
Aerospace Engineering Res: 404 603 9160
Georgia Inst. of Technology
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