[petsc-users] KSPsolve performance tuning

[Smith, Barry F.]

   What pressure solver is OpenFOAM using? Are you using the same convergence tolerance for the pressure solver for the two approaches? Have you tried PETSc with a simpler solver: -pc_type bjacobi or -pc_type asm ; the problem is pretty small and maybe at this size hypre is overkill?

   Barry


> On Sep 13, 2018, at 12:58 PM, Edoardo alinovi <edoardo.alinovi at gmail.com> wrote:
> 
> Hello PETSc's frieds,
> 
> It is a couple of weeks that I am trying to enhance the perforamance of my code. Actually I am solving NS equation for a 3D problem of 220k cells with 4procs on my laptop (i7-7800k @ 2.3Ghz with dynamic overclocking). I have installed petsc under linux suse 15 in a virtual machine (I do not know if this is important or not). 
> 
> After some profiling, I can  see that the bottle neck is inside KSPSolve while solving pressure equation (solved with cg + hypre pc). For this reason my code is running twice time slower than openFOAM and the gap is only due the solution of pressure. Have you got some hints for me?  At this point I am sure I am doing something wrong! I have attached the log of a test simulation.
> 
> Thank you very much!
> 
> ------
> 
> Edoardo Alinovi, Ph.D.
> 
> DICCA, Scuola Politecnica
> Universita' di Genova
> 1, via Montallegro
> 16145 Genova, Italy
> 
> email: edoardo.alinovi at dicca.unige.it
> Tel: +39 010 353 2540
> 
> 
> <run_log_view.txt>