MPI_Error_string(ret, err_string, &length);
XBT_INFO("%d request done, return %s", rank, err_string);
XBT_INFO("%d still has MPI rank %d and global variable %d", param->rank, rank, global_rank);
MPI_Error_string(ret, err_string, &length);
XBT_INFO("%d request done, return %s", rank, err_string);
XBT_INFO("%d still has MPI rank %d and global variable %d", param->rank, rank, global_rank);