[petsc-users] consistence of PETSC/SLEPC with MPI, BLACS, SCALAPACK calls...

[Satish Balay]

On Thu, 30 Nov 2017, Giacomo Mulas wrote:

> On Mon, 27 Nov 2017, Satish Balay wrote:
> 
> > These questions are more pertinant to MKL - i.e what interface does
> > MKL ilp64 blacs library provide for Cblacs_get() etc..
> 
> I don't know if it's more pertinent, but indeed it is pertinent also to MKL.

Well PETSc does not use scalapack/blacs. Its primarily a dependency
for MUMPS [which does not support 64bit indices anyway]

And you are calling [mkl] blacs directly from your code. Hence its
primarily pertinant to MKL - and its usage from your code.

Sure - you are using PETSc datatypes - but thats secondary to this
issue. You have to figure out what datatypes ilp64 mkl blacs expects
[and what mpi datatypes it uses] - and thats what you would have to
pass in - when calling blacs functions.

> The pertinence with SLEPC/PETSC is that my code _also_ uses SLEPC/PETSC, and
> I run it both on an architecture in which SLEPC/PETSC is compiled against
> the ilp64 mkl and on architectures in which SLEPC/PETSC is compiled against
> stock standard scalapack/blacs/lapack/blas libs.
> 
> >
> > The following url has some info - and some references to ilp64 MPI
> > https://software.intel.com/en-us/forums/intel-math-kernel-library/topic/474149
> 
> thanks for the link.
> 
> > [PETSc is not tested with ilp64 MPI]
> 
> well, the version of the code that does not yet use scalapack but only slepc
> appears to work fine with it.

Yes - this is expected to work - as we support using ilp64 blas/lapack from PETSc

Satish