On Aug 30, 2013, at 1:04 PM, France Boillod-Cerneux <[email protected]>
wrote:
> Dear PETSc user,
>
> I am using MatMult() function in a C++ program.
>
> Currently, my matrix is MATMPIAIJ format type, and I load the matrix from a
> binary file at petsc format. let's call the matrix A:
>
> I know before the execution the global rows, columns and nnz.
>
> my program is doing something like:
>
PetscLogDouble prevflops,myflops;
> global loop
> //begin to measure flop rate
PetscGetFlops(&prevFlops);
> inner loop
> MatMult(A,x,y)
> end inner loop
PetscGetFlops(&myflops);
my flops -= prevFlops; /* each MPI process has how many flops IT has
done
> //want to know Flop rate of Matmult at this point
> end global loop
>
> I am looking for a function to know at runtime the flop rate for each process
> regarding matmult function.
>
> I had a look at pdf of Loic Gouarin (introduction to pertsc, performance May
> 2013) but it does not correspond to what i want, or i missunderstood?
>
> My other solution is using the matmpiaijsetpreallocation and therefore know
> the complete parallel distribution of A, but this implies a pre-treatment on
> my matrix A.
>
> I was wondering if i can create my matrix A without knowing in advance the
> parallel distribution and then collect the information about parallel
> distribution?
>
> Or more easier, if a function like PetscGetFlops could solve my problem?
> so far i understood that this function measure the flop since the begining of
> program, but this is not what i want to use, i want to have the flop ratio
> right after ending the inner loop, and this, for each global iteration
>
> Any ideas/suggestions would help,
>
> Thank you very much,
>
> France
>
>
> --
> Bien cordialement - Best regards - Mit freundlichen Grüßen,
>
> France BOILLOD-CERNEUX
> PhD Student, Laboratoire d'Informatique Fondamentale de Lille
> (LIFL), CNRS
>
> [email protected]
> Tel. : +33 (0) 1 6908 - 9527
> Tel. : +33 (0) 6 4781 - 3059
>
> DEN/DANS/DM2S
> CEA Saclay
> 91191 Gif-sur-Yvette
> FRANCE
>
> http://www.lifl.fr/
> www-centre-saclay.cea.fr
>
