[petsc-users] [Ext] Re: Two simple questions on building

[Matthew Knepley]

On Wed, Mar 16, 2022 at 9:30 AM Ernesto Prudencio via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Thanks, Matt.
>
>
> Regarding the blas/lapack used by PETSc via the –download-fblaslapack
> configuration option: are the libraries consumed as .a or as .so?
>

Those are .a


> My question was related to the situation where they would be .so, with my
> LD_LIBRARY_PATH pointing first to the MKL path and then to the PETSc path.
> Would that cause PETSc to use the blas/lapack from MKL at run time, instead
> of the blas/lapack use at compilation time?
>

It would, but since BLAS/LAPACK does not have a standard ABI there can
still be problems I think.


> Regarding your question on (a): at the end of the PETSc building process,
> a docker image has to be created, but then there are some soft links in the
> supplied MKL library which are not resolved. The problem boils down to
> details on where the MKL is actually located, and the overall compilation
> environment used for all software, where certain rules have to be enforced
> for all.
>

Oh, yes for a container you would have to install MKL into the container
just as you would install it anywhere else. Then install PETSc in the
container.
I have done that for another project and got it to work.

  Thanks,

    Matt


> Cheers,
>
>
>
> Ernesto.
>
>
>
> *From:* Matthew Knepley <knepley at gmail.com>
> *Sent:* Wednesday, March 16, 2022 5:45 AM
> *To:* Ernesto Prudencio <EPrudencio at slb.com>
> *Cc:* PETSc users list <petsc-users at mcs.anl.gov>
> *Subject:* [Ext] Re: [petsc-users] Two simple questions on building
>
>
>
> On Wed, Mar 16, 2022 at 1:04 AM Ernesto Prudencio via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
>
> Hi.
>
>
>
> I have an application that uses MKL for some convolution operations. Such
> MKL functionality uses, I suppose, BLAS/LAPACK underneath.
>
>
>
> This same application of mine also uses PETSc for other purposes. I can
> supply blas and lapack to PETSc in two ways:
>
>    1. Using the configuration
>    option--with-blaslapack-lib="-L${MKL_DIR}/lib/intel64 -lfile1 -lfile2 … ".
>    For reasons related to compilation environments + docker images + cloud, I
>    am having issues with this option (a) _*after*_ PETSc builds
>    successfully (both make and make install work fine).
>    2. Using the configuration option --download-fblaslapack=yes. This
>    options works fine for the purpose of generating my application executable.
>
>
>
> If I use option (b), I understand that I will have two different
> blas/lapack codes available during the execution of my application: one
> from MKL, the other being the one that PETSc downloads during its
> configuration.
>
>
>
> Question 1) Do you foresee any potential run time issue with option (b)?
>
>
>
> All those BLAS/LAPACK functions have the same name. If MKL does something
> slightly different in one, you could have problems. The annoying thing is
> that it will probably work 99% of the time.
>
>
>
> What problem do you have with a)?
>
>
>
> Question 2) In the case PETSc, is there any problem if run “make” and
> “make install” without specifying PETSC_ARCH?
>
>
>
> It will choose an ARCH if you do not specify one.
>
>
>
>   Thanks,
>
>
>
>      Matt
>
>
>
>
>
> Thank you in advance,
>
>
>
> Ernesto.
>
>
>
> Schlumberger-Private
>
>
>
>
> --
>
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
>
>
> https://www.cse.buffalo.edu/~knepley/
> <https://urldefense.com/v3/__http:/www.cse.buffalo.edu/*knepley/__;fg!!Kjv0uj3L4nM6H-I!1YIcv0EOPSK_loLVyLJiARQF8B0wUp96gOBWK4L-7PdpPbhDZIEQPSkoe3a2pw$>
>
> Schlumberger-Private
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20220316/43ffde35/attachment.html>