Q-Logic IB6054601-00 D manual Troubleshooting InfiniPath MPI Troubleshooting

Q

C – Troubleshooting InfiniPath MPI Troubleshooting

integer count, datatype, root, comm, ierror

!Call the Fortran 77 style implicit interface to "mpi_bcast" external mpi_bcast

call mpi_bcast(buffer, count, datatype, root, comm, ierror) end subroutine additional_mpi_bcast_for_character

end module additional_bcast program myprogram

use mpi

use additional_bcast implicit none character*4 c integer master, ierr, i

! Explicit integer version obtained from module "mpi"

call mpi_bcast(i, 1, MPI_INTEGER, master, MPI_COMM_WORLD, ierr)

!Explicit character version obtained from module "additional_bcast" call mpi_bcast(c, 4, MPI_CHARACTER, master, MPI_COMM_WORLD, ierr)

end program myprogram

This is equally applicable if the module "mpi" provides only a lower-rank interface and you want to add a higher-rank interface. An example would be where the module explicitly provides for 1-D and 2-D integer arrays but you need to pass a 3-D integer array.

However, some care must be taken. One should only do this if:

■The module "mpi" provides an explicit Fortran 90 style interface for "mpi_bcast." If the module "mpi" does not, the program will use an implicit Fortran 77 style interface, which does not perform any type checking. Adding an interface will cause type-checking error messages where there previously were none.

■The underlying function really does accept any data type. It is appropriate for the first argument of "mpi_bcast" because the function operates on the underlying bits, without attempting to interpret them as integer or character data.

C.8.11

Lock Enough Memory on Nodes When Using a Batch Queuing System

InfiniPath MPI requires the ability to lock (pin) memory during data transfers on each compute node. This is normally done via /etc/initscript, which is created or modified during the installation of the infinipath RPM (setting a limit of 64MB, with the command "ulimit -l 65536").

Some batch systems, such as SLURM, propagate the user’s environment from the node where you start the job to all the other nodes. For these batch systems, you may need to make the same change on the node from which you start your batch jobs.

IB6054601-00 D C-21