[Beowulf] evaluating FLOPS capacity of our cluster

Gus Correa gus at ldeo.columbia.edu
Mon May 11 14:58:41 PDT 2009

Rahul Nabar wrote:
> On Mon, May 11, 2009 at 2:09 PM, Gus Correa <gus at ldeo.columbia.edu> wrote:
>> Of course even the HPL Rmax is
>> not likely to be reached by a real application,
>> with I/O, etc, etc.
>> Rahul and I may be better off testing Rmax with our real
>> programs.
> I do know that these benchmarks can be somewhat unrealistic and the
> real test is the actual application that you want to run. I already
> have those timed-benchmarks for my particular computational chemistry
> code and more specifically with a job representative of what we might
> consider "typical" for computations on our cluster.
Hi Rahul, list

For reliable estimates of the computational effort required by research
projects, project duration, etc, there is no real substitute than what
you did: timing your applications on typical runs.

> Yet, while speaking to larger audiences sometimes FLOPS becomes a
> commonly reported and understood benchmark and hence my desire to
> compute it.
 > That is another reason why the exact-FLOPS capacity is of not so much
 > interest to me as a approximate value.

You are very right.
The larger audiences include
grant proposal agencies (NSF, NOAA, NIH,etc),
potential donors,
upper administration officers in the academia, etc.
Even nominal Gflops are OK for a grant proposal,
as long as you tell they are nominal numbers.
Donors may be happy to read that your cluster, which
was partially funded by their XYZ-Foundation, broke the
Top500 HPL benchmark Teraflop barrier.
Directors and Deans may approach donors telling with plans
to expand the cluster to a (nominal) capacity of 3 Teraflops, and so on.
As long as *you* don't get carried along by those numbers!  :)

Gus Correa
Gustavo Correa
Lamont-Doherty Earth Observatory - Columbia University
Palisades, NY, 10964-8000 - USA

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