The FNN (Flat Neighborhood Network) paradox

Robert G. Brown rgb at
Wed Feb 28 16:28:46 PST 2001

On Thu, 22 Feb 2001, Jon Tegner wrote:

> We are using an inexpensive D-link switch (DES-3225G), and are using
> channel bonding through two VLANS on that  (one) switch. Really don't
> know what kind of improvement to expect, so I'm attaching two figures,
> the first one  shows signature graphs (throughput as a function of
> time) using mpi and tcp with and without channel bonding  (obtained by
> netpipe). From this one it looks like channel bonding is working OK.
>  But when it comes to my application (simulation of a detonation in gas
> phase) improvement is not very spectacular  (not worth it?). The figure
> shows the same case for three different meshes (480x50 cells to 1920x200
> cells), and  displays the speed up as a function of number of nodes.
> Obviously I couldn't expect better scaling for the large case, but for
> the medium and the small one, are they  showing the kind of improvement
> one could expect? Or is it likely that something is wrong with our
> set-up?
> Thanks in advance for any comments,


  a) Do you know if your application is CPU bound or network bound?

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