[Mpi3-tools] Questions on the F2008 profiling interface issues
Rolf Rabenseifner
rabenseifner at hlrs.de
Mon Oct 3 05:18:19 CDT 2011
Dear all,
according to pages:lines in
https://svn.mpi-forum.org/trac/mpi-forum-web/attachment/ticket/229/mpi-report-F2008-2011-09-08-changeonlyplustickets.pdf
and the decision of the Santorini 2011 meeting,
we should add the following text to accommodate the tools implementors.
P559:20-21 reads
equals .FALSE.. If
but should read
equals .FALSE., and
After p559 the following text should be added:
----------------------------
To simplify the development of profiling libraries, the MPI routines
are grouped together and it is required that
if the peer routine of a group is available within an MPI library
with one of its possible linker names then all of the routines
in this group must be also provided according to the same linker
name scheme, and if the peer routine is not available through
a linker name scheme then all other routines have also not to be
available through this scheme.
Peer routines and their groups:
- MPI_ALLOC_MEM
MPI_ALLOC_MEM and MPI_WIN_ALLOCATE.
- MPI_FREE_MEM
Only this routine is in this group.
- MPI_GET_ADDRESS
MPI_GET_ADDRESS and MPI_ADDRESS.
- MPI_SEND
All routines with choice buffer arguments that
are not declared as ASYNCHRONOUS within the mpi_f08 module
and exist already in MPI-2.2.
- MPI_NEIGHBOR_ALLTOALL
All routines with choice buffer arguments that
are not declared as ASYNCHRONOUS within the mpi_f08 module
and are new in MPI-3.0.
- MPI_ISEND
All routines with choice buffer arguments that
are declared as ASYNCHRONOUS within the mpi_f08 module
and exist already in MPI-2.2.
- MPI_IBCAST
All routines with choice buffer arguments that
are declared as ASYNCHRONOUS within the mpi_f08 module
and are new in MPI-3.0.
- MPI_OP_CREATE
Only this routine is in this group.
- MPI_REGISTER_DATAREP
Only this routine is in this group.
- MPI_COMM_KEYVAL_CREATE
All other routines with callback function arguments.
- MPI_COMM_DUP_FN
All predefined callback routines.
- MPI_COMM_RANK
All other MPI routines that exist already in MPI-2.2.
- MPI_IBARRIER
All other MPI routines that are new in MPI-3.0.
Advice to implementors.
If all the following conditions are fulfilled
(which is the case for most compilers)
- the handles in the mpi_f08 module occupy one Fortran
numerical storage unit (same as an INTEGER handle), and
- the internal argument passing used to pass an actual ierror
argument to a non optional ierror dummy argument is binary
compatible to passing an actual ierror argument to an ierror
dummy argument that is declared as OPTIONAL, and
- the internal argument passing for ASYNCHRONOUS and
non-ASYNCHRONOUS arguments is the same, and
- the internal routine call mechanism is the same for
the Fortran and the C compiler, and
- the compiler does not provide TR 29113,
then for most groups, the implementor may use the same
internal routine implementations for all Fortran support
methods with only different linker names.
For TR 29113 quality, new routines are needed only for
the routine groups of MPI_ISEND and MPI_IBCAST.
End of advice to implementors.
----------------------------
Not directly relevant for the tools people, but giving the reason
for differentiating several Choice-buffer routine groups,
the following changes are also done:
P552:14-18 read
- Set the INTEGER compile-time constant MPI_SUBARRAYS_SUPPORTED to
.TRUE. and declare choice buffers using the Fortran 2008 TR 29113
feature assumed-type and assumed-rank, i.e., TYPE(*), DIMENSION(..),
if the underlying Fortran compiler supports it. With this,
non-contiguous sub-arrays can be used as buffers in nonblocking routines.
but should read
- Set the INTEGER compile-time constant MPI_SUBARRAYS_SUPPORTED to
.TRUE. and declare choice buffers using the Fortran 2008 TR 29113
feature assumed-type and assumed-rank, i.e., TYPE(*), DIMENSION(..)
in all nonblocking, split collective and persistent communication
routines,
if the underlying Fortran compiler supports it. With this,
non-contiguous sub-arrays can be used as buffers in nonblocking routines.
Rationale. In all blocking routines, i.e., if the choice-buffer
is not declared as ASYNCHRONOUS, the TR 29113 feature is not needed
for the support of non-contiguous buffers because the compiler
can pass the buffer by in-and-out-copy through a contiguous scratch
array. End of rationale.
P555:7-10 read
- Set the INTEGER compile-time constant MPI_SUBARRAYS_SUPPORTED to
.TRUE. if all choice buffer arguments
are declared with TYPE(*), DIMENSION(..), otherwise set it to
.FALSE.. With MPI_SUBARRAYS_SUPPORTED==.TRUE., non-contiguous
subarrays can be used as buers in nonblocking routines.
but should read
- Set the INTEGER compile-time constant MPI_SUBARRAYS_SUPPORTED to
.TRUE. if all choice buffer arguments
in all nonblocking, split collective and persistent communication
routines
are declared with TYPE(*), DIMENSION(..), otherwise set it to
.FALSE.. With MPI_SUBARRAYS_SUPPORTED==.TRUE., non-contiguous
subarrays can be used as buers in nonblocking routines.
I'll try to be at the tel-con today.
Best regards
Rolf
----- Original Message -----
> From: "Martin Schulz" <schulzm at llnl.gov>
> To: "Marc-Andre Hermanns" <m.a.hermanns at grs-sim.de>
> Cc: "MPI3 Tools" <mpi3-tools at lists.mpi-forum.org>, "Martin Schulz" <schulz6 at llnl.gov>, "Craig E Rasmussen"
> <rasmussn at lanl.gov>, "Rolf Rabenseifner" <rabenseifner at hlrs.de>, "Jeff Squyres" <jsquyres at cisco.com>, "Andreas
> Knüpfer" <andreas.knuepfer at tu-dresden.de>, "Todd Gamblin" <tgamblin at llnl.gov>, "Tobias Hilbrich"
> <tobias.hilbrich at tu-dresden.de>, "MPI-3 Fortran working group" <mpi3-fortran at lists.mpi-forum.org>
> Sent: Sunday, October 2, 2011 6:13:46 AM
> Subject: Re: [Mpi3-tools] Questions on the F2008 profiling interface issues
> Hi Marc-Andre,
>
> On Sep 30, 2011, at 6:27 AM, Marc-Andre Hermanns wrote:
>
> > Martin,
> >
> >> I was in Dresden the last few days (visiting the Vampir group, in
> >> particular Andreas Knuepfer and Tobias Hilbrich who are responsible
> >> for
> >> their MPI wrappers) and we sat down to talk about the issues around
> >> the
> >> profiling interface in ticket #229.
> >>
> >> Here is a quick summary with a few questions that came up:
> >>
> >> * With the new Fortran symbol naming variants, there are 6 or 8 or
> >> 10
> >> versions for every MPI subroutine. Tools could intercept all
> >> versions by
> >> providing own symbols for all versions.
> >
> > If it is clear which name the symbols have, additional symbol names
> > should be easy to generate, so at this stage I think it doesn't
> > matter
> > much, whether we have 6, 8, or 10 different schemes to cover. Right?
>
> I agree - as long as we can generate a full list of names, we can
> intercept them all. Adding wrappers shouldn't be a problem.
>
> >
> >> Now the problem: Within the wrapper function a tool needs to call
> >> the
> >> correct PMPI call which usually is the same prefix (either '_f08',
> >> '_f', '__' etc.) as the MPI call it is in. A mapping to matching C
> >> functions (as most tools do it now) is not possible due to problems
> >> with calling conventions for callback routines.
> >
> > As far as I know our wrappers call the C routines, because we jump
> > through all sorts of hoops to get a proper Fortran to C conversion
> > and
> > back. So in this regard, we need to fix this. Interestingly this has
> > not
> > popped up yet.
>
> I agree - this is remarkable.
>
> >
> > If we write Fortran wrappers in Fortran, how would a Fortran wrapper
> > compiled with Fortran 77 have to call the C measurement code inside
> > the
> > wrapper? If the Fortran compiler implicitly adds underscores to the
> > calls, do I have to provide a special Fortran interface to my
> > measurement system then?
>
> That is a question for the Fortran experts.
>
> >
> >> * Would the following solution work? All wrappers for Fortran are
> >> written
> >> in Fortran instead of C.
> >> [...]
> >> For every MPI function, there are 6 or 8 variants and all of them
> >> need to be provided by a tool. This would probably mean that we
> >> have
> >> to compile wrappers with all three calling conventions (mpif.h, use
> >> mpi_f and use mpi_f08) and then link them together?
> >
> > Don't we need to compile with all three calling conventions on all
> > possible compilers on a given system?
>
> Also, here, I think the Fortran experts need to weigh in.
>
> >
> > We currently provide all 4 name-mangling schemes with every install
> > of
> > Scalasca, because we had some issues with applications using two
> > different Fortran compilers for different sub-modules. (This came up
> > in
> > a project some years back, and ever since then we provide all
> > schemes in
> > the same library and it seems to work.)
> >
> >> * As discussed at the forum, if we want to keep our tools in C
> >> (which is
> >> probably still the easier and better option), we need to know the
> >> symbols
> >> on the "p" side and we need a portable way to figure this out. We
> >> talked
> >> about the solution of two groups of routines - one for which we
> >> have _f08
> >> symbols for one for which we don't. Rolf, how will you add this to
> >> the
> >> standard, in particular how will you form those groups.
> >
> > I started to get some doubts about this approach. One of the issues
> > was
> > that some choice-buffer routines had names longer than the proposed
> > limit. So they need to be mangled differently, especially, their
> > symbol
> > needs to be shortened. And as I understood it, the current idea is
> > to
> > leave it to the MPI implementation to define the shortened name.
>
> I thought that was just for the argument checking in mpif.h and that
> we decided to not support this. Are there more locations were the
> names are too long?
>
> >
> > It is one thing, finding out which suffix is used. Finding how
> > function
> > names are mangled without any form of restricting to possible
> > schemes
> > seems to be another ball game?
> >
> > Am I missing something?
>
> Yes, if we do have to shorten names, I agree - I think, though, we got
> around the issue, or did we not?
>
> >
> > I think, as it was pointed out in Santorini with the Fortran
> > Bindings in
> > general, we (or at least I) don't have enough Fortran expertise to
> > think
> > this through all to the end and consider all implications. I think
> > it
> > would be a great benefit to have people of the Fortran WG to join on
> > the
> > call on Monday. I hope this is possible.
>
> Yes, that would be great - all are cc-ed.
>
> Martin
>
>
> >
> > Cheers,
> > Marc-Andre
> > --
> > Marc-Andre Hermanns
> > German Research School for
> > Simulation Sciences GmbH
> > c/o Laboratory for Parallel Programming
> > 52056 Aachen | Germany
> >
> > Tel +49 241 80 99753
> > Fax +49 241 80 6 99753
> > Web www.grs-sim.de
> >
> > Members: Forschungszentrum Jülich GmbH | RWTH Aachen University
> > Registered in the commercial register of the local court of
> > Düren (Amtsgericht Düren) under registration number HRB 5268
> > Registered office: Jülich
> > Executive board: Prof. Marek Behr Ph.D. | Dr. Norbert Drewes
> >
>
> ________________________________________________________________________
> Martin Schulz, schulzm at llnl.gov, http://people.llnl.gov/schulzm
> CASC @ Lawrence Livermore National Laboratory, Livermore, USA
--
Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner at hlrs.de
High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner
Nobelstr. 19, D-70550 Stuttgart, Germany . (Office: Allmandring 30)
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