[petsc-users] parallel matmult flop measure

[France Boillod-Cerneux]

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:

global loop
     //begin to measure flop rate
     inner loop
           MatMult(A,x,y)
     end inner loop
     //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*

France.Boillod-Cerneux at cea.fr
Tel. : +33 (0) 1 6908 - 9527
Tel. : +33 (0) 6 4781 - 3059

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