Hello Gus,
Thank you very much for your answer but I do not think that this is the
problem.I have changed everything in a C program and I obtain the same
result.
Does anyone have any idea about the problem?
Sofia
----- Original Message -----
From: "Gus Correa" <g...@ldeo.columbia.edu>
To: "Open MPI Users" <us...@open-mpi.org>
Sent: Tuesday, September 16, 2008 9:42 PM
Subject: Re: [OMPI users] Problem with MPI_Send and MPI_Recv
Hello Sofia and list
I am not a C++ person, I must say.
However, I noticed that you wrote the program in C++,
compiled it with the mpiCC (C++) compiler wrapper,
but your MPI calls are written with the MPI C binding syntax,
not the MPI C++ binding syntax.
E.g. :
MPI_Send(&sum,1,MPI_INT,0,1,MPI_COMM_WORLD);
instead of something like this:
comm.Send(&sum,1,MPI::INT,0,1);
I wonder if this mixed C++ / C environment may have caused some of the
trouble,
although I am not sure about that.
Since the specific C++ commands that you use are basically for
printing messages, it may be easier to transform the program into
a C program, by replacing the appropriate include files
and the C++ specific I/O commands by C commands,
and then compile the program again with mpicc.
An alternative is to write the MPI function calls in the C++ binding
syntax.
I hope this helps.
Gus Correa
--
---------------------------------------------------------------------
Gustavo J. Ponce Correa, PhD - Email: g...@ldeo.columbia.edu
Lamont-Doherty Earth Observatory - Columbia University
P.O. Box 1000 [61 Route 9W] - Palisades, NY, 10964-8000 - USA
---------------------------------------------------------------------
Sofia Aparicio Secanellas wrote:
Hello,
I am new using MPI. I want to run a simple program (I enclose the
program) in 2 different computers. I have installed MPI in both
computers. I have compiled the program using:
mpiCC -o PruebaSumaParalela.out PruebaSumaParalela.cpp
I have copied the executable PruebaSumaParalela.out to my /home
directoy in both computers. Then I run:
mpirun -np 2 --host 10.4.5.123,edu@10.4.5.126 --prefix /usr/local
./PruebaSumaParalela.out
The 10.4.5.123 computer prints:
Inicio
Inicio
totalnodes:2
mynode:0
Inicio Recv
totalnodes:2
mynode:1
Inicio Send
sum:375250
The edu@10.4.5.126 <mailto:edu@10.4.5.126> computer prints:
Inicio
Inicio
totalnodes:2
mynode:1
Inicio Send
sum:375250
totalnodes:2
mynode:0
Inicio Recv
But the program does not finish on any computer. It seems that the Send
and Recv does not work. Master computer is waiting to receive something
that the slave does not send.
Do you know what the problem could be ?
Thank you very much.
Sofia
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------------------------------------------------------------------------
#include<iostream.h>
#include<mpi.h>
int main(int argc, char ** argv){
int mynode, totalnodes;
int sum,startval,endval,accum;
printf("Inicio\n");
MPI_Status status;
MPI_Init(&argc,&argv);
MPI_Comm_size(MPI_COMM_WORLD, &totalnodes);
MPI_Comm_rank(MPI_COMM_WORLD, &mynode);
printf("totalnodes: %d\n",totalnodes);
printf("mynode: %d\n",mynode);
sum = 0;
startval = 1000*mynode/totalnodes+1;
endval = 1000*(mynode+1)/totalnodes;
for(int i=startval;i<=endval;i=i+1)
sum = sum + i;
if(mynode!=0){
printf("Inicio Send\n");
printf("sum: %d\n",sum);
MPI_Send(&sum,1,MPI_INT,0,1,MPI_COMM_WORLD);
printf("Send sum\n");
}
else
for(int j=1;j<totalnodes;j=j+1){
printf("Inicio Recv\n");
MPI_Recv(&accum,1,MPI_INT,j,1,MPI_COMM_WORLD, &status);
printf("RECV accum\n");
sum = sum + accum;
printf("Sum\n");
}
printf("Final\n");
if(mynode == 0)
cout << "The sum from 1 to 1000 is: " << sum << endl;
MPI_Finalize();
}
------------------------------------------------------------------------
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