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Subject: Re: [OMPI users] Issue with Profiling Fortran code
From: Anthony Chan (chan_at_[hidden])
Date: 2008-12-05 18:58:02


Hi Nick,

----- "Nick Wright" <nwright_at_[hidden]> wrote:

> Hi Antony
>
> That will work yes, but its not portable to other MPI's that do
> implement the profiling layer correctly unfortunately.

I guess I must have missed something here. What is not portable ?

>
> I guess we will just need to detect that we are using openmpi when our
>
> tool is configured and add some macros to deal with that accordingly.
> Is
> there an easy way to do this built into openmpi?

MPE by default provides a fortran to C wrapper library, that way user
does not have to know about the MPI implementation's fortran to C layer.
MPE user can specify the fortran to C layer that implementation have
during MPE configure.

Since MPI implementation's fortran to C library does not change often,
so writing a configure test to check for libmpi_f77.*, libfmpich.*,
or libfmpi.* should get you covered for most platforms.

A.Chan
>
> Thanks
>
> Nick.
>
> Anthony Chan wrote:
> > Hope I didn't misunderstand your question. If you implement
> > your profiling library in C where you do your real instrumentation,
> > you don't need to implement the fortran layer, you can simply link
> > with Fortran to C MPI wrapper library -lmpi_f77. i.e.
> >
> > <OMPI>/bin/mpif77 -o foo foo.f -L<OMPI>/lib -lmpi_f77
> -lYourProfClib
> >
> > where libYourProfClib.a is your profiling tool written in C.
> > If you don't want to intercept the MPI call twice for fortran
> program,
> > you need to implment fortran layer. In that case, I would think
> you
> > can just call C version of PMPI_xxx directly from your fortran
> layer, e.g.
> >
> > void mpi_comm_rank_(MPI_Comm *comm, int *rank, int *info) {
> > printf("mpi_comm_rank call successfully intercepted\n");
> > *info = PMPI_Comm_rank(comm,rank);
> > }
> >
> > A.Chan
> >
> > ----- "Nick Wright" <nwright_at_[hidden]> wrote:
> >
> >> Hi
> >>
> >> I am trying to use the PMPI interface with OPENMPI to profile a
> >> fortran
> >> program.
> >>
> >> I have tried with 1.28 and 1.3rc1 with --enable-mpi-profile
> switched
> >> on.
> >>
> >> The problem seems to be that if one eg. intercepts to call to
> >> mpi_comm_rank_ (the fortran hook) then calls pmpi_comm_rank_ this
> then
> >>
> >> calls MPI_Comm_rank (the C hook) not PMPI_Comm_rank as it should.
> >>
> >> So if one wants to create a library that can profile C and Fortran
> >> codes
> >> at the same time one ends up intercepting the mpi call twice. Which
> is
> >>
> >> not desirable and not what should happen (and indeed doesn't happen
> in
> >>
> >> other MPI implementations).
> >>
> >> A simple example to illustrate is below. If somebody knows of a fix
> to
> >>
> >> avoid this issue that would be great !
> >>
> >> Thanks
> >>
> >> Nick.
> >>
> >> pmpi_test.c: mpicc pmpi_test.c -c
> >>
> >> #include<stdio.h>
> >> #include "mpi.h"
> >> void mpi_comm_rank_(MPI_Comm *comm, int *rank, int *info) {
> >> printf("mpi_comm_rank call successfully intercepted\n");
> >> pmpi_comm_rank_(comm,rank,info);
> >> }
> >> int MPI_Comm_rank(MPI_Comm comm, int *rank) {
> >> printf("MPI_comm_rank call successfully intercepted\n");
> >> PMPI_Comm_rank(comm,rank);
> >> }
> >>
> >> hello_mpi.f: mpif77 hello_mpi.f pmpi_test.o
> >>
> >> program hello
> >> implicit none
> >> include 'mpif.h'
> >> integer ierr
> >> integer myid,nprocs
> >> character*24 fdate,host
> >> call MPI_Init( ierr )
> >> myid=0
> >> call mpi_comm_rank(MPI_COMM_WORLD, myid, ierr )
> >> call mpi_comm_size(MPI_COMM_WORLD , nprocs, ierr )
> >> call getenv('HOST',host)
> >> write (*,*) 'Hello World from proc',myid,' out
> of',nprocs,host
> >> call mpi_finalize(ierr)
> >> end
> >>
> >>
> >>
> >> _______________________________________________
> >> users mailing list
> >> users_at_[hidden]
> >> http://www.open-mpi.org/mailman/listinfo.cgi/users
> > _______________________________________________
> > users mailing list
> > users_at_[hidden]
> > http://www.open-mpi.org/mailman/listinfo.cgi/users
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