Wrong mpi number of processors

Question

Sorry, I\'m sure making a silly mistake, but did not work out.

I\'m compiling a simple mpi hello world:

#include 
#include 

         


        

Answer 1

I don't know how you can compile it:

 int main (argc, argv)
 int argc;
 char *argv[];

will be changed to

 int main (int argc, char *argv[])

another point is that mpi is message passing interface that passes messages between processes not cores or processors if you have a 4 core system you can run your code with so many processes as your ram permits but only 4 processes are working at any time and other processes must wait so it is efficient that you use only 4 process.

Answer 2

There is nothing wrong with your code. The only problem that can be is with your mpi installation.

Notice:

There is a differences between processor to core. its not the same thing.

Answer 3

In this case, you need mpiexec from the 'mpich2' package.

Firstly, remove all mpi packages that installed on your computer. If your server is Ubuntu, you can use the command:

sudo apt-get purge mpi mpich2 openmpi-common

To make sure that you have removed all the packages, try this command

which mpiexec

If you got nothing in response, you already removed all the packages.

Then reinstall the package of mpich2

sudo apt-get install mpich2

Try to compile and run your code again! Hope this help!

Answer 4

INSTALL

sudo apt-get install libopenmpi-dev openmpi-bin openmpi-doc

Now compile and execute code