On Wed, Apr 10, 2013 at 10:04 AM, Chris Kees <cekees@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