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Re: [PATCH] 2015Q2 patches and one outstanding issue with pkgtools/p5-pkgsrc-Dewey



On 08/15/15 16:10, Aleksej Saushev wrote:
   Hello,

Thomas Orgis <thomas.orgis%uni-hamburg.de@localhost> writes:

Patch 4: mk-mpi-buildlink3-do-nothing-for-native.patch

This is not a little fixup but a feature patch: Add the option of

MPI_TYPE = native

to use a system-installed MPI library. This I will exclusively use on
our system from now on, since we install several toolchains with MPI
included, pkgsrc built on top of that.
Could you, please, in the future reflect such things in subject header?
It took some extra effort in finding your letter. Discussing MPI in a letter
with subject that tells absolutely nothing about even the possibility of it,
is somewhat confusing.

+.if $(MPI_TYPE) == "native"
+# nothing

I don't like this approach. I see following problems with it.

Most likely your "native" implementation is just some other version of
MPICH or OpenMPI. In this case, it is unclear why a package that uses,
say, MPICH suddenly is marked as "native".

It is argued from time to time that we want to support MPI the way we
support, say, Python. That is we want to allow installing several
versions of packages that utilise different MPI implementations.
In this case, you may want for some obvious reasons to use native MPICH
and native OpenMPI. Your "native" is even more confusing then, since
you'll have packages that use MPI_TYPE "mpich" and "openmpi".

Since your native implementation is most likely MPICH or OpenMPI,
your use case is naturally supported by builtin framework.
Using builtin framework helps not only you but future use case of
supporting several MPI frameworks at the same time.

In my opinion, you should rather take the approach of adding builtin
support to OpenMPI and MPICH packages. If you want any help with this,
I'm glad to offer it.


I'll second Alesej's comments and offer to help.

I would argue that any package using MPI going forward should at least be specific about which MPI implementation it uses and preferable support multiple implementations which can be installed simultaneously.

Some users on the same HPC cluster may need to use fftw with mpich2 while others will need to use fftw with openmpi. This can be easily achieved by installing mpich2 and all packages that use it under $PREFIX/mpich2 and similarly openmpi-based packages under $PREFIX/openmpi. This is just an example strategy. Nothing has been decided yet, but we have some packages in wip that demonstrate it.

Regards,

    Jason


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  Jason W. Bacon
  jwbacon%tds.net@localhost

  If a problem can be solved,
  there's no need to worry.
If it cannot be solved, then
  worrying will do no good.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



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