[petsc-users] floating point exception… but only when >4 cores are used...

Sat Apr 28 17:45:04 CDT 2012

On Sat, Apr 28, 2012 at 6:39 PM, Andrew Spott <andrew.spott at gmail.com>wrote:

> >-start_in-debugger noxterm -debugger_nodes 14
>
> All my cores are on the same machine, is this supposed to start a debugger
> on processor 14? or computer 14?
>

Neither. This spawns a gdb process on the same node as the process with MPI
rank 14. Then attaches gdb
to process 14.

    Matt

> I don't think I have x11 setup properly for the compute nodes, so x11
> isn't really an option.
>
> Thanks for the help.
>
> -Andrew
>
>
> On Apr 27, 2012, at 7:26 PM, Satish Balay wrote:
>
> > On Fri, 27 Apr 2012, Andrew Spott wrote:
> >
> >> I'm honestly stumped.
> >>
> >> I have some petsc code that essentially just populates a matrix in
> parallel, then puts it in a file.  All my code that uses floating point
> computations is checked for NaN's and infinities and it doesn't seem to
> show up.  However, when I run it on more than 4 cores, I get floating point
> exceptions that kill the program.  I tried turning off the exceptions from
> petsc, but the program still dies from them, just without the petsc error
> message.
> >>
> >> I honestly don't know where to go, I suppose I should attach a
> debugger, but I'm not sure how to do that for multi-processor code.
> >
> > assuming you have X11 setup properly from compute nodes you can run
> > with the extra option '-start_in_debugger'
> >
> > If X11 is not properly setup - and you'd like to run gdb on one of the
> > nodes [say node 14 where you see SEGV] - you can do:
> >
> > -start_in-debugger noxterm -debugger_nodes 14
> >
> > Or try valgrind
> >
> > mpiexec -n 16 valgrind --tool=memcheck -q ./executable
> >
> >
> > For debugging - its best to install with --download-mpich [so that its
> > valgrind clean] - and run all mpi stuff on a single machine - [usually
> > X11 works well from a single machine.]
> >
> > Satish
> >
> >>
> >> any ideas?  (long error message below):
> >>
> >> -Andrew
> >>
> >> [14]PETSC ERROR:
> ------------------------------------------------------------------------
> >> [14]PETSC ERROR: Caught signal number 8 FPE: Floating Point
> Exception,probably divide by zero
> >> [14]PETSC ERROR: Try option -start_in_debugger or
> -on_error_attach_debugger
> >> [14]PETSC ERROR: or see
> http://www.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#valgrind[14]PETSCERROR: or try
> http://valgrind.org on GNU/linux and Apple Mac OS X to find memory
> corruption errors
> >> [14]PETSC ERROR: likely location of problem given in stack below
> >> [14]PETSC ERROR: ---------------------  Stack Frames
> ------------------------------------
> >> [14]PETSC ERROR: Note: The EXACT line numbers in the stack are not
> available,
> >> [14]PETSC ERROR:       INSTEAD the line number of the start of the
> function
> >> [14]PETSC ERROR:       is given.
> >> [14]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> >> [14]PETSC ERROR: Signal received!
> >> [14]PETSC ERROR:
> ------------------------------------------------------------------------
> >> [14]PE[15]PETSC ERROR:
> ------------------------------------------------------------------------
> >> [15]PETSC ERROR: Caught signal number 8 FPE: Floating Point
> Exception,probably divide by zero
> >> [15]PETSC ERROR: Try option -start_in_debugger or
> -on_error_attach_debugger
> >> [15]PETSC ERROR: or see
> http://www.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#valgrind[15]PETSCERROR: or try
> http://valgrind.org on GNU/linux and Apple Mac OS X to find memory
> corruption errors
> >> [15]PETSC ERROR: likely location of problem given in stack below
> >> [15]PETSC ERROR: ---------------------  Stack Frames
> ------------------------------------
> >> [15]PETSC ERROR: Note: The EXACT line numbers in the stack are not
> available,
> >> [15]PETSC ERROR:       INSTEAD the line number of the start of the
> function
> >> [15]PETSC ERROR:       is given.
> >> [15]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> >> [15]PETSC ERROR: Signal received!
> >> [15]PETSC ERROR:
> ------------------------------------------------------------------------
> >> [15]PETSC ERROR: Petsc Release Version 3.2.0, Patch 6, Wed Jan 11
> 09:28:45 CST 2012
> >> [14]PETSC ERROR: See docs/changes/index.html for recent updates.
> >> [14]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
> >> [14]PETSC ERROR: See docs/index.html for manual pages.
> >> [14]PETSC ERROR:
> ------------------------------------------------------------------------
> >> [14]PETSC ERROR: /home/becker/ansp6066/local/bin/finddme on a linux-gnu
> named photon9.colorado.edu by ansp6066 Fri Apr 27 18:01:55 2012
> >> [14]PETSC ERROR: Libraries linked from
> /home/becker/ansp6066/local/petsc-3.2-p6/lib
> >> [14]PETSC ERROR: Configure run at Mon Feb 27 11:17:14 2012
> >> [14]PETSC ERROR: Configure options
> --prefix=/home/becker/ansp6066/local/petsc-3.2-p6 --with-c++-support
> --with-fortran --with-mpi-dir=/usr/local/mpich2 --with-shared-libraries=0
> --with-scalar-type=complex
> --with-blas-lapack-libs=/central/intel/mkl/lib/em64t/libmkl_core.a
> --with-clanguage=cxx
> >> [14]PETSC ERROR:
> ------------------------------------------------------------------------
> >> [14]TSC ERROR: Petsc Release Version 3.2.0, Patch 6, Wed Jan 11
> 09:28:45 CST 2012
> >> [15]PETSC ERROR: See docs/changes/index.html for recent updates.
> >> [15]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
> >> [15]PETSC ERROR: See docs/index.html for manual pages.
> >> [15]PETSC ERROR:
> ------------------------------------------------------------------------
> >> [15]PETSC ERROR: /home/becker/ansp6066/local/bin/finddme on a linux-gnu
> named photon9.colorado.edu by ansp6066 Fri Apr 27 18:01:55 2012
> >> [15]PETSC ERROR: Libraries linked from
> /home/becker/ansp6066/local/petsc-3.2-p6/lib
> >> [15]PETSC ERROR: Configure run at Mon Feb 27 11:17:14 2012
> >> [15]PETSC ERROR: Configure options
> --prefix=/home/becker/ansp6066/local/petsc-3.2-p6 --with-c++-support
> --with-fortran --with-mpi-dir=/usr/local/mpich2 --with-shared-libraries=0
> --with-scalar-type=complex
> --with-blas-lapack-libs=/central/intel/mkl/lib/em64t/libmkl_core.a
> --with-clanguage=cxx
> >> [15]PETSC ERROR:
> ------------------------------------------------------------------------
> >> [15]PETSC ERROR: User provided function() line 0 in unknown directory
> unknown file
> >> application called MPI_Abort(MPI_COMM_WORLD, 59) - process 14PETSC
> ERROR: User provided function() line 0 in unknown directory unknown file
> >> application called MPI_Abort(MPI_COMM_WORLD, 59) - process
> 15[0]0:Return code = 0, signaled with Interrupt
> >
>
>

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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