To be fair, Microsoft just doesn't have resources left over for MPI
after all they've been putting into making sure nobody in China learns
about Tiananmen Square.

"Smith, Barry F. via petsc-dev" <[email protected]> writes:

>   MS-MPI has in their include file
>
> #define MPI_VERSION     2
> #define MPI_SUBVERSION  0
>
> Their last release was Oct 2018 
> https://docs.microsoft.com/en-us/message-passing-interface/microsoft-mpi-release-notes
>
>   They also don't provide a mpi.mod file though they do provide mpif.h and 
> Fortran stubs in their library see the discussion at
> https://bitbucket.org/petsc/petsc/pull-requests/1666/error-and-stop-configure-if-the-mpi-module/diff
>
>   As a side note, Microsoft's C compiler also does not support all of C99 :-)
>
>
>
>> On May 24, 2019, at 5:23 PM, Jeff Hammond via petsc-dev 
>> <[email protected]> wrote:
>> 
>> No, it's really not better to keep it.  MPI 2.2 support is ubiquitous.  It 
>> has been 10 years, which is 1-2 lifetimes of an HPC system or PC.  Anybody 
>> who insists on using an MPI library that doesn't support 2.2 should accept 
>> that they must use a version of PETSc from 2018 or earlier.
>> 
>> In the HPC space, MPI 3.0 has been available on most machines for 5+ years.  
>> The last platform that I used that didn't have MPI 2.2 support was IBM Blue 
>> Gene/P and all of those machines were taken offline long ago.  As of SC18, 
>> the MPI 3.1 support matrix (see below) is essentially complete and the only 
>> feature that PETSc would need to test for is MS-MPI's lack of neighborhood 
>> collectives.
>> 
>> I am aware that people are using Open-MPI 1.10 in production today.  These 
>> people are bad.  Don't allow their poor life choices to force the pollution 
>> of PETSc source code with unnecessary macros.
>> 
>> https://lists.mpi-forum.org/pipermail/mpi-forum/2014-June/006086.html <- MPI 
>> 3.0
>> https://lists.mpi-forum.org/pipermail/mpi-forum/2016-November/006532.html <- 
>> MPI 3.1
>> https://lists.mpi-forum.org/pipermail/mpi-forum/2018-November/006783.html <- 
>> MPI 3.1
>> 
>> Jeff
>> 
>> On Fri, May 24, 2019 at 2:15 PM Zhang, Junchao via petsc-dev 
>> <[email protected]> wrote:
>> PetscSF has many PETSC_HAVE_MPI_REDUCE_LOCAL. It is disturbing. But consider 
>> the time gap between MPI-2.0 (1998) and MPI-2.2 (2009), it is better to keep 
>> it.
>> 
>> 
>> On Fri, May 24, 2019 at 3:53 PM Jed Brown <[email protected]> wrote:
>> "Zhang, Junchao" <[email protected]> writes:
>> 
>> > How about stuff in MPI-2.2 (approved in 2009), the last of MPI-2.x, e.g., 
>> > PETSC_HAVE_MPI_REDUCE_LOCAL?
>> 
>> Currently we only require MPI-2.0, but I would not object to increasing
>> to MPI-2.1 or 2.2 if such systems are sufficiently rare (almost
>> nonexistent) in the wild.  I'm not sure how great the benefits are.
>> 
>> > On Fri, May 24, 2019 at 2:51 PM Jed Brown via petsc-dev 
>> > <[email protected]<mailto:[email protected]>> wrote:
>> > Lisandro Dalcin via petsc-dev 
>> > <[email protected]<mailto:[email protected]>> writes:
>> >
>> >> These two are definitely wrong, we need PETSC_HAVE_MPI_XXX instead.
>> >
>> > Thanks, we can delete both of these cpp guards.
>> >
>> >> include/petscsf.h:#if defined(MPI_REPLACE)
>> >
>> > MPI-2.0
>> >
>> >> src/sys/objects/init.c:#if defined(PETSC_USE_64BIT_INDICES) ||
>> >> !defined(MPI_2INT)
>> >
>> > MPI-1.0
>> 
>> 
>> -- 
>> Jeff Hammond
>> [email protected]
>> http://jeffhammond.github.io/

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