On Mon, Sep 28, 2009 at 11:28 AM, Aniruddha Marathe <marathe.aniruddha@gmail.com> wrote:

Hi Jeff,

Thanks for the pointers. I tried with both CFLAGS=-g3 and --enable-debug (separately), however, I am still unable to jump into the MPI source. It seems I am missing a small step(s) somewhere.

I compiled my MPI application with the new library built with above flags, ran it and attached gdb to one of the processes. Following are the steps that I performed with gdb:

...
...
0x00110416 in __kernel_vsyscall ()
Missing separate debuginfos, use: debuginfo-install glibc.i686
(gdb) dir /home/amarathe/mpi/svn_openmpi/ompi-trunk/ompi/mpi/c
Source directories searched: /home/amarathe/mpi/svn_openmpi/ompi-trunk/ompi/mpi/c:$cdir:$cwd
(gdb) break MPI_Barrier
Breakpoint 1 at 0x155596

When gdb hits breakpoint 1, it jumps at the address but cannot find the source file for 'MPI_Barrier' definition.

Breakpoint 1, 0x00155596 in PMPI_Barrier () from /home/amarathe/mpi/openmpi/openmpi-1.3.3_install/lib/libmpi.so.0
(gdb) s
Single stepping until exit from function PMPI_Barrier,
which has no line number information.
main (argc=1, argv=0xbf9a1484) at smg2000.c:114
114 P = num_procs;
(gdb)

Is this the right approach?

Thanks,
Aniruddha

On Mon, Sep 28, 2009 at 8:40 AM, Jeff Squyres <jsquyres@cisco.com> wrote:

You might want to just configure Open MPI with:

./configure CFLAGS=-g3 ...

That will pass "-g3" to every Makefile in Open MPI.

FWIW: I do variants on this technique and gdb is always able to jump to the right source location if I "break MPI_Barrier" (for example). We actually have a "--enable-debug" option to OMPI's configure, but it does turn on a bunch of other debugging code that will definitely result in performance degradation at run-time (one of its side effects is to add "-g" to every Makefile).

On Sep 28, 2009, at 5:57 AM, Aniruddha Marathe wrote:

Hello,

I am new to OpenMPI library and I am trying to step through common MPI
communication calls using gdb. I attach gdb to one of the processes
(using the steps mentioned on the OpenMPI Debugging FAQ page) and set
a breakpoint on 'MPI_Barrier' and expect gdb to jump into the
definition of MPI_Barrier function.

I've manually added -g3 compilation flag to the Makefiles in some of
the directories that I thought relevant ({ROOT}/ompi/mpi/c etc). I
also specified the source file paths in gdb using the 'dir' command.
However, gdb is unable to jump into the appropriate source location
when it hits the breakpoint.

Could anyone please let me know if I am missing something here?

Thanks for looking into my post.

Regards,
Aniruddha
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Jeff Squyres
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