[mvapich-discuss] Downloading mvapich2-gdr versions and compatibility between versions

[Raghu Reddy]

Hi Hari,

 

Thank you for this information!

 

Here is some more information about the motivation behind this question.  In
our environment we cannot directly install from the RPMs because we install
it in a location different from where it wants to install by default. So we
cpio to extract the file and move it out desired location (we install in
"/apps/mvapich2-gdr" directory). 

 

And because we are doing that, we have been modifying all the wrapper
scripts (mpicc, mpif90, etc)  to have the new paths.  Since we are modifying
the paths anyway I was thinking if GNU version is compatible with the other
two compilers we could have one installation and create wrappers for GNU,
Intel, and PGI compilers.

 

It is good to know that they should be compatible, but as you have
explained, it is better to have specific versions built using specific
compilers. 

 

Thanks,

Raghu

 

 

 

 

From: Subramoni, Hari [mailto:subramoni.1 at osu.edu] 
Sent: Thursday, April 12, 2018 9:18 AM
To: Raghu Reddy <raghu.reddy at noaa.gov>; mvapich-discuss at cse.ohio-state.edu
<mvapich-discuss at mailman.cse.ohio-state.edu>
Cc: Subramoni, Hari <subramoni.1 at osu.edu>
Subject: RE: [mvapich-discuss] Downloading mvapich2-gdr versions and
compatibility between versions

 

Hello.

 

I do not understand the question very clearly. For instance, what do you
mean by installing a GNU version of MVAPICH2-GDR and using it with Intel/PGI
compilers? Do you mean to say that you have an application that does
something like this

 

CC=pgcc

MPICC=mpicc

 

CC <some_c_file.c>

MPICC <some_mpi_c_file.c>

 

Link all of them together with CC as the linker?

 

We have never tried such a combination internally. In principle, it may
work, however you could hit weird issues due to minor differences between
how compilers perform optimizations.

 

Further, it is not just compatibility, the choice of compilers can also
affect the performance of end applications and the optimization level that
gets used.

 

Thx,

Hari.

 

From: mvapich-discuss-bounces at cse.ohio-state.edu
<mailto:mvapich-discuss-bounces at cse.ohio-state.edu>  On Behalf Of Raghu
Reddy
Sent: Wednesday, April 11, 2018 8:45 AM
To: mvapich-discuss at cse.ohio-state.edu
<mailto:mvapich-discuss at cse.ohio-state.edu>
<mvapich-discuss at mailman.cse.ohio-state.edu
<mailto:mvapich-discuss at mailman.cse.ohio-state.edu> >
Subject: [mvapich-discuss] Downloading mvapich2-gdr versions and
compatibility between versions

 

Dear mvapich2 team,

 

When trying to download mvapich2-gdr, there is a table of options available
to download.  For example when I look at the row headings:

 

GNU/4.8.5 and PGI (for various scheduler combinations).

 

Previously whenever we needed an Intel version we requested it and that was
provided very promptly!   Thank you, and very much appreciated!  :)

 

One question I have is, both PGI and Intel are compatible with GNU as long
as FORTRAN 90 modules are not involved.  So as long as we're not using
"module use mpi" is it fair to say we could just install the GNU version and
use it with any of these three compilers (GNU, Intel, and PGI)? 

 

Is it fair to say separate versions are provided primarily because of
incompatibility introduced used by:

 

-        Fortran 90 (primarily by "module use mpi"?)

-        C++, which may not be compatible for a similar reason

 

As long as our codes are not using C++ MPI constructs and Fortran does not
use "module use mpi"  is there any reason to explicitly request an Intel
build?

 

Thanks!

Raghu

 

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