[petsc-dev] examples/benchmarks for weak and strong scaling exercise

[Matthew Knepley]

On Wed, Apr 10, 2013 at 10:04 AM, Chris Kees <cekees at gmail.com> wrote:

> Hi guys,
>
> Could somebody point me to some examples you guys routinely use for
> weak and strong scaling studies (maybe even with scripts, option
> files,  or prior results on recent hardware)? I'm thinking of 3D
> Poisson with finite differences and geometric multigrid or something
> like that.
>

I am trying to write this stuff down, but there is not much written right
now.
Let's start at the beginning. SNES ex5 is the simplest example that can be
used for this I think. It is 2D Poisson (actually Bratu). Its really easy
to get
weak scaling by adjusting the grid size using

  -da_grid_x <m> -da_grid_y <n>

You can turn on MG using

  -pc_type mg -pc_mg_levels <n>

although the slightly non-intuitive thing is that then the grid size you
input is
for the coarse grid.


> We've been trying to work toward scaling studies of the field split
> and Schur complement preconditioners for our multiphase flow solvers,
> but I'm realizing that we need to do more thorough testing of the
> petsc installation itself and make sure we're using timing/profiling
> "best practices" and such.
>
> We are using petsc-dev on the hardware below. I promise to quit using
> petsc-dev as soon as the next release comes out:) Several versions of
> PETSc are also installed by the system maintainers, but my sense is
> that there is very little testing done on any of the installations.
>

I think using petsc-dev is the "right thing", and it is now much much more
stable (the 'master' branch on BitBucket).

  Thanks,

     Matt


> http://www.erdc.hpc.mil/hardware/index.html
>
> Chris
>



-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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