[Beowulf] Performance characterising a HPC application

Toon Knapen toon.knapen at fft.be
Mon Mar 19 06:20:21 PDT 2007

stephen mulcahy wrote:
> I'm still unsure what the bottleneck currently is. My hunch is that a 
> faster interconnect *should* give a better performance but I'm not sure 
> how to quantify that. Do others here running MPI jobs see big 
> improvements in using Infiniband over Gigabit for MPI jobs or does it 
> really depend on the characteristics of the MPI job? What 
> characteristics should I be looking for?

Long time ago I was working with some guys who were using Dimemas 
(http://www.cepba.upc.es/dimemas/). This tool allows you to simulate the 
app on any network.

You first need to run the app once to collect a trace of all MPI-calls 
that are performed during a run. Next, the tool allows you to simulate 
your app (based on the trace to the MPI-calls) on any network (taking 
into account how long the communication takes on the network you wanted 
to simulate).

I can imagine this tool might be able to simulate your app on other 
types of networks and investigate the speedup you might obtain.


disclaimer: I have no affiliation with the University of Barcelona.

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