Need help! How to compile parallel C program?

[kelvin490]

I have a simple testing program like this:

/*The Parallel Hello World Program*/
#include <stdio.h>
#include <mpi.h>

main(int argc, char **argv)
{
int node;

MPI_Init(&argc,&argv);
MPI_Comm_rank(MPI_COMM_WORLD, &node);

printf("Hello World from Node %d\n",node);

MPI_Finalize();
}

My program is, I can't compile this program using gcc, and I can't find something like pgcc in ubuntu. How should I compile this program? After compiling, what should I do to run this program?


Thank you.

[NovaAesa]

Could you show the command you used to invoke gcc as well as the error message(s) it produced?

[kelvin490]

Could you show the command you used to invoke gcc as well as the error message(s) it produced?

I use gcc to compile but cannot work

shsh@ubuntu:~/Desktop/Try$ gcc tryhpc.c -o try.exe
tryhpc.c:3:17: error: mpi.h: No such file or directory
tryhpc.c: In function ‘main’:
tryhpc.c:10: error: ‘MPI_COMM_WORLD’ undeclared (first use in this function)
tryhpc.c:10: error: (Each undeclared identifier is reported only once
tryhpc.c:10: error: for each function it appears in.)

[NovaAesa]

I did some quick googling, I don't think you are meant to use gcc to compile the program, I'm not sure though - I've never done anything with MPI before. I'm trying to work it out now :)

[schauerlich]

What version of MPI are you using? If it's MPICH or LAM, check out these tutorials:

http://heather.cs.ucdavis.edu/~matloff/MPI/NotesMPICH.NM.html
http://heather.cs.ucdavis.edu/~matloff/MPI/NotesLAM.NM.html

General MPI information here:
http://heather.cs.ucdavis.edu/~matloff/mpi.html

To put it lightly, setting up MPI correctly is a bitch. Good luck.

[NovaAesa]

Okay, I got *something* happening. Install the package libopenmpi-dev
sudo apt-get install libopenmpi-dev
Then you should be able to compile your program with
mpicc helloworld.c
You can then run it with


./a.out

although I'm getting some strange errors when I run the program.

[kelvin490]

[/code]although I'm getting some strange errors when I run the program.[/QUOTE]


Thanks, it can be run now but I got some error like this:

shsh@ubuntu:~/Desktop/Try$ mpicc tryhpc.c -o try2
tryhpc.c:6: warning: return type defaults to ‘int’
tryhpc.c: In function ‘main’:
tryhpc.c:15: warning: control reaches end of non-void function
shsh@ubuntu:~/Desktop/Try$ ./try2
Hello World from Node 0

BTW, can I use something like mpirun to run it? I want to try to use both cores of my computer to run it and make it shows Node 1 also besides Node0.

Thanks a lot.

[cgroza]

[/code]although I'm getting some strange errors when I run the program.


Thanks, it can be run now but I got some error like this:

shsh@ubuntu:~/Desktop/Try$ mpicc tryhpc.c -o try2
tryhpc.c:6: warning: return type defaults to ‘int’
tryhpc.c: In function ‘main’:
tryhpc.c:15: warning: control reaches end of non-void function
shsh@ubuntu:~/Desktop/Try$ ./try2
Hello World from Node 0

BTW, can I use something like mpirun to run it? I want to try to use both cores of my computer to run it and make it shows Node 1 also besides Node0.

Thanks a lot.
Declare main as int main and don't forget to return from it and the warnings should go away.

[kelvin490]

Declare main as int main and don't forget to return from it and the warnings should go away.

Thank you, man.

[ramsrambo]

Install openmpi-bin pkg by

sudo apt-get install openmpi-bin

then once installation is successful then
mpirun ./try

it is working for me:)