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Subject: Re: [OMPI users] OpenMPI 1.3.2 with PathScale 3.2
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2009-05-18 21:09:13


Hah; this is probably at least tangentially related to

     http://www.open-mpi.org/faq/?category=building#pathscale-broken-with-mpi-c++-api

I'll be kind and say that Pathscale has been "unwilling to help on
these kinds of issues" with me in the past as well. :-)

It's not entirely clear from the text, but I guess that sounds like
Pathscale is unsupported on GCC 3.x systems...? Is that what you
parse his answer to mean?

On May 18, 2009, at 5:09 PM, Joshua Bernstein wrote:

> Well,
>
> I spoke Gautam Chakrabarti at Pathscale. It seems the long
> and short of it is
> that using OpenMP with C++ with a GNU3.3 (RHEL4) frontend creates some
> limitations inside of pathCC. On a RHEL4 system, the compilier
> activates the
> proper frontend for GCC 3.3, this is what creates the crash. As
> suggested I
> forced the compilier to use the newer frontend with the -gnu4 option
> and the
> build completes without an issue. Sad though that they aren't trying
> to be
> backwards compatible, or even testing on RHEL4 systems. I imagine
> there is still
> large group of people using RHEL4.
>
> Perhaps this is an OMPI FAQ entry?
>
> The full response from Pathscale appears below:
>
> ---SNIP---
> It appears you are using the compiler on a relatively old linux
> distribution
> which has a default GCC compiler based on version 3.3. Our compiler
> has a
> front-end that is activated on such systems, and a different newer
> improved
> front-end which is activated on the newer GCC4-based systems. Our
> compiler is
> tested on GCC-based systems with versions up to 4.2. I see that you
> are using
> OpenMP (using -mp). C++ OpenMP has limitations when being used with
> the GNU3.3
> based front-end, and is only fully supported when on a GNU4 based
> system.
>
> You can invoke the newer front-end by the option -gnu4 on a GNU3
> based system.
> While compiling this particular file may work with -gnu4 on a GNU3
> based system,
> it is generally not safe to use this option for C++ on a GNU3 based
> system due
> to incompatibility issues.
>
> The ideal fix would be to try your compilation on a GNU4 based linux
> distribution.
> ---END SNIP---
>
> -Joshua Bernstein
> Software Engineer
> Penguin Computing
>
> Jeff Squyres wrote:
> > FWIW, I'm able to duplicate the error. Looks definitely like
> a[nother]
> > pathscale bug to me.
> >
> > Perhaps David's suggestions to disable some of the optimizations may
> > help; otherwise, you can disable that entire chunk of code with the
> > following:
> >
> > --enable-contrib-no-build=vt
> >
> > (as Ralph mentioned, this VampirTrace code is an add-on to Open MPI;
> > it's not part of core OMPI itself)
> >
> >
> > On May 15, 2009, at 9:17 AM, David O. Gunter wrote:
> >
> >> Pathscale supports -O3 (at least as of the 3.1 line). Here are
> some
> >> suggestions from the 3.2 Users Manual you may also want to try.
> >>
> >> -david
> >>
> >>
> >> If there are numerical problems with -O3 -OPT:Ofast, then try
> either
> >> of the
> >> following:
> >>
> >> -O3 -OPT:Ofast:ro=1
> >> -O3 -OPT:Ofast:div_split=OFF
> >>
> >> Note that ’ro’ is short for roundoff.
> >>
> >> -Ofast is equivalent to -O3 -ipa -OPT:Ofast -fno-math-errno -
> ffast-math
> >> so similar cautions apply to it as to -O3 -OPT:Ofast.
> >>
> >> To use interprocedural analysis without the "Ofast-type"
> optimizations,
> >> use either of the following:
> >> -O3 -ipa
> >> -O2 -ipa
> >>
> >> Testing different optimizations can be automated by pathopt2. This
> >> program
> >> compiles and runs your program with a variety of compiler options
> and
> >> creates a sorted list of the execution times for each run.
> >>
> >> --
> >> David Gunter
> >> Los Alamos National Laboratory
> >>
> >> > Last I checked when we were building here, I'm not sure Pathscale
> >> > supports -O3. IIRC, O2 is the max supported value, though it
> has been
> >> > awhile since I played with it.
> >> >
> >> > Have you checked the man page for it?
> >> >
> >> > It could also be something in the VampirTrace code since that
> is where
> >> > you are failing. That is a contributed code - not part of OMPI
> itself
> >> > - so we would have to check with those developers.
> >> >
> >> >
> >> > On May 14, 2009, at 2:49 PM, Åke Sandgren wrote:
> >> >
> >> >> On Thu, 2009-05-14 at 13:35 -0700, Joshua Bernstein wrote:
> >> >>> Greetings All,
> >> >>>
> >> >>> I'm trying to build OpenMPI 1.3.2 with the Pathscale
> compiler,
> >> >>> version 3.2. A
> >> >>> bit of the way through the build the compiler dies with what it
> >> >>> things is a bad
> >> >>> optimization. Has anybody else seen this, or know a work
> around for
> >> >>> it? I'm
> >> >>> going to take it up with Pathscale of course, but I thought I'd
> >> >>> throw it out here:
> >> >>>
> >> >>> ---SNIP---
> >> >>> /opt/pathscale/bin/pathCC -DHAVE_CONFIG_H -I. -I../.. -I../../
> >> >>> extlib/otf/otflib
> >> >>> -I../../extlib/otf/otflib -I../../vtlib/ -I../../vtlib -
> >> >>> D_GNU_SOURCE -mp
> >> >>> -DVT_OMP -O3 -DNDEBUG -finline-functions -pthread -MT vtfilter-
> >> >>> vt_tracefilter.o
> >> >>> -MD -MP -MF .deps/vtfilter-vt_tracefilter.Tpo -c -o vtfilter-
> >> >>> vt_tracefilter.o
> >> >>> `test -f 'vt_tracefilter.cc' || echo './'`vt_tracefilter.cc
> >> >>> Signal: Segmentation fault in Global Optimization -- Dead Store
> >> >>> Elimination phase.
> >> >>> Error: Signal Segmentation fault in phase Global Optimization
> --
> >> >>> Dead Store
> >> >>> Elimination -- processing aborted
> >> >>> *** Internal stack backtrace:
> >> >>> pathCC INTERNAL ERROR: /opt/pathscale/lib/3.2/be died due to
> signal 4
> >> >>
> >> >> Haven't seen it. But I'm only using -O2 when building openmpi.
> >> >> Report it quickly, if we're lucky they might get a fix into
> the 3.3
> >> >> release that is due out very soon. (I just got the beta
> yesterday)
> >> >>
> >> >> --
> >> >> Ake Sandgren, HPC2N, Umea University, S-90187 Umea, Sweden
> >> >> Internet: ake_at_[hidden] Phone: +46 90 7866134 Fax: +46 90
> 7866126
> >> >> Mobile: +46 70 7716134 WWW: http://www.hpc2n.umu.se
> >> >>
> >> >> _______________________________________________
> >> >> users mailing list
> >> >> users_at_[hidden]
> >> >> http://www.open-mpi.org/mailman/listinfo.cgi/users
> >> >
> >> >
> >> > _______________________________________________
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> >> > http://www.open-mpi.org/mailman/listinfo.cgi/users
> >> >
> >>
> >> _______________________________________________
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> >
> >
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-- 
Jeff Squyres
Cisco Systems