[Beowulf] Re: building a new cluster

Tim Mattox tmattox at gmail.com
Fri Sep 3 11:08:16 PDT 2004

Hello SCH,
That is an interesting graph.  Are you running a representative size data set?
2 Million gridpoints seems small compared to what I'm used to seeing CFD
people run on our clusters.  But I don't know your code or problem set,
so 2 Million may be just what you want to work with.

I say this because the wallclock times in your graph are rather short, with
all but one of the runs on faster than 100 Mbit networks at under 10 seconds.
You may be seeing the job's startup overhead more than your actual code's

If you can, try running a bigger job, and/or for more timesteps.  More timesteps
will hide the startup overhead, and a bigger job (if that is representative
of your desired runs) should allow you to scale to larger numbers of nodes.

On Fri, 3 Sep 2004 09:55:11 -0700 (PDT), SC Huang <schuang21 at yahoo.com> wrote:
> Hi,
> I just posted some timing results from my MPI code here:
> http://www.geocities.com/schuang21/index.html
> More are coming soon. It looks like even with gigabit switch (at least
> for this MPI code) using more than 16 nodes is not good...
> Any comment or suggestion is very welcome. :-)

Tim Mattox - tmattox at gmail.com - http://homepage.mac.com/tmattox/

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