> On Sep 13, 2018, at 1:55 PM, Edoardo alinovi <[email protected]>
> wrote:
>
> Hello Barry,
>
> Thank you very much for your replay! Maybe the best feature of PETSc is this
> mailing list :) You are right cg + block Jcoby is twice faster than hypre,
> but still a bit slower than OF. I have definitely to test a bigger case. It
> seems that hypre loses a lot of time in setting up the PC. Is this normal?
Yes, BoomerAMG (or any AMG method) has "large" setup times that don't scale
as well as the solve time. Thus if you can reuse the setup for multiple solves
you gain a great deal. The best case is, of course, where the same Poisson
problem (with a different right hand side obviously) has to be solved many
times. I noticed in your log_view that it seems to need to do a new setup for
each solve.
Barry
>
> Thank you!
>
>
>
> ------
>
> Edoardo Alinovi, Ph.D.
>
> DICCA, Scuola Politecnica
> Universita' di Genova
> 1, via Montallegro
> 16145 Genova, Italy
>
> email: [email protected]
> Tel: +39 010 353 2540
>
>
>
> 2018-09-13 20:10 GMT+02:00 Smith, Barry F. <[email protected]>:
>
> 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 <[email protected]>
> > 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: [email protected]
> > Tel: +39 010 353 2540
> >
> >
> > <run_log_view.txt>
>
>
