NAME

MPI_Comm_size - Returns the size of a communicator

SYNOPSIS

#include <mpi.h> 
int MPI_Comm_size(MPI_Comm comm , int *size ); 
#include <pmpi.h> 
int PMPI_Comm_size(MPI_Comm comm , int *size ); 

INPUT PARAMETER

comm - communicator (handle)

OUTPUT PARAMETER

size - the local size of the communicator (integer).

DESCRIPTION

The MPI_Comm_size() function is used to obtain the size of the communicator. It returns the total number of ranks within an intracommunicator. It returns the number of local ranks of an intercommunicator. The communicator must be a valid one (not MPI_COMM_NULL). PMPI_Comm_size() is the profiling version of this function.

ERRORS

All MPI routines except for MPI_Wtime and MPI_Wtick return an error value. The the current MPI error handler is invoked if this return value is not MPI_SUCCESS. The default error handler aborts, but this may be changed with by using the MPI_Errhandler_set() function. The predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned instead. Note that MPI does not guarentee that an MPI program can continue past an error. In this implementation, all errors except MPI_ERR_INTERN or MPI_ERR_OTHER should always be recoverable.

MPI_SUCCESS - No error;

MPI_ERR_COMM - Invalid communicator;

MPI_ERR_ARG - Invalid output pointer.

SEE ALSO

MPI_Comm_size (3) MPI_Comm_remote_size (3) MPI_Comm_rank (3) MPI_Comm_create (3) MPI_Comm_free (3) MPI_Intercomm_create (3) MPI_Intercomm_merge (3)

• Lockless
• MPI Documentation
• MPI_Comm_size