Iterative and direct parallel linear solvers in a hybrid MPI/OpenMP high performance computational engineering simulations

Research topic and goals

This research action aims at improving the parallel scalability and robustness of the hybrid MPI/OpenMP high performance computational code Alya developed at BSC by using the parallel linear solvers designed at Inria. In that framework both parallel sparse direct and hybrid iterative/direct linear solvers will be integrated in the Alya code to study their performance and identify their possible bottlenecks. This action will contribute to the definition of the global API for the solver stack currently developed at Inria that will ease the integration and testing of the linear solver in any large simulation code.

Results for 2016/2017

A database with testcases has been created on Marenostrum. This database includes a series of representative examples to test unsymmetric, symmetric and SPD matrices. In addition, different mesh topologies have been considered to assess the effects of mesh anisotropy, computational domain elongation, etc. Benchmarking is currently carried out to compare Alya internal solvers and MAPHYS.

Visits and meetings

  • Guillaume Houzeaux (BSC) and Mariano Vázquez (BSC) met INRIA team at Bordeaux, 14-15 Oct. 2016.
  • Guillaume Houzeaux (BSC) met INRIA team at Bordeaux, 24-26 Feb. 2016.
  • INRIA met BSC team at Barcelona, Nov. 2016.

Impact and publications

None yet.

    Future plans

    We intend to complete the full integration of the Inria solvers with their current individual API in the Alya code so that scalability studies on different applications representative of Alya simulations can be performed (incompressible/compressible fluid, structure mechanics). Hopefully some of them will reveal numerical or software features to be further studied.

    References

    1. Vázquez, M., G. Houzeaux, S. Koric, A. Artigues, J. Aguado-Sierra, Arı́s R., D. Mira, et al. 2015. “Alya: Multiphysics Engineering Simulation Towards Exascale.” J. Comput. Sci.
      @article{VazquezEtAl2015,
        author = {V\'azquez, M. and Houzeaux, G. and Koric, S. and Artigues, A. and Aguado-Sierra, J. and Ar\'{\i}s, R. and Mira, D. and Calmet, H. and Cucchietti, F. and Owen, H. and Taha, A. and Burness, E.D. and Cela, J.M. and Valero, M.},
        journal = {J. Comput. Sci.},
        keywords = {Alya},
        title = {Alya: Multiphysics Engineering Simulation Towards Exascale},
        year = {2015}
      }
      
    2. Houzeaux, G, R Aubry, and M Vázquez. 2011. “Extension Of Fractional Step Techniques for Incompressible Flows: The Preconditioned Orthomin(1) for the Pressure Schur Complement.” Comput. &Amp; Fluids 44: 297–313.
      @article{HouzeauxEtAl2011,
        author = {Houzeaux, G and Aubry, R and V\'azquez, M},
        journal = {Comput. \& Fluids},
        keywords = {Orthomin(1) iteration},
        pages = {297--313},
        title = {Extension of fractional step techniques for incompressible flows: The preconditioned Orthomin(1) for the pressure Schur complement},
        volume = {44},
        year = {2011}
      }
      
    3. Houzeaux, G, M Vázquez, R Aubry, and JM Cela. 2009. “A Massively Parallel Fractional Step Solver For Incompressible Flows.” J. Comp. Phys 228 (17): 6316–32.
      @article{HouzeauxEtAl2009,
        author = {Houzeaux, G and V\'azquez, M and Aubry, R and Cela, JM},
        journal = {J. Comp. Phys},
        number = {17},
        pages = {6316--6332},
        title = {A Massively Parallel Fractional Step Solver for Incompressible Flows},
        volume = {228},
        year = {2009}
      }