[petsc-users] Two simple questions on building

[Matthew Knepley]

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/ <http://www.cse.buffalo.edu/~knepley/>
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