jb_am_i_irank0

Name

jb_am_i_irank0 - singles out one compute node process per BGAS IO node.

Synopsis

#include <mpi.h>
#include "jbcnl.h"

int jb_am_i_irank0();

Include with -I/bgsys/local/bgas/jbrt/jbcn/include, link with -L/bgsys/local/bgas/jbrt/jbcn/lib -ljbcn.

Description

jb_am_i_irank0() chooses one compute node process (i.e. MPI task) out of the set of processes living on compute nodes connected to a given IO node. That is, for each IO node, there is exactly one MPI task which lives on a compute node connected to it and on which jb_am_i_irank0() returns TRUE (1).

Return value

jb_am_i_irank0() returns 1 if and only if the caller's MPI rank is lowest among the MPI ranks of tasks connected to the same IO node as the caller, 0 else.

Errors

None.

Thread safety

jb_am_i_irank0() is thread-safe.