[petsc-dev] Handling ESSL + Lapack and PESSL

[Jed Brown]

On Mon, 13 Sep 2010 13:18:54 -0500, Barry Smith <bsmith at mcs.anl.gov> wrote:
>    Does PESSL have some of the same symbols in it as ESSL? If it has
>    any symbols that are identical but map to different functions there
>    would be a problem. We haven't messed with PESSL in many, many
>    years so perhaps they fixed this? Also PESSL use to use threads to
>    do some of its parallelism. In our MPI on every core model of PETSc
>    this doesn't make sense because the cores will be over subscribed
>    with several PESSL threads per core. Basically it use to be if you
>    linked PESSL into PETSc things didn't work properly. If that is
>    fixed then the check could be removed.

I don't know, maybe Aron or someone who does more work with BG/P can
comment.

>     You really don't want to link LAPACK first because then basically
>     you get the LAPACK versions of the codes which (one would presume)
>     are slower then the same interfaces in ESSL (otherwise why bother
>     using ESSL).

For the fast BLAS?  I agree with your point, but I suspect lots of users
would prefer to tolerate a somewhat slower GEEV in exchange for not
having to write two versions of their code.

>     When is KAUST going to grow a brain and order a IBM Blue Waters
>     machine as the next machine and not a IBM Blue Gene?

Presumably as soon as IBM is ready to install it in 2009.

Jed