[Beowulf] raw ethernet

[050675 at student.unife.it]

> Do you mean using raw ethernet packets on a flat bridged network to do
> point to point IPCs in a cluster application?  No TCP/IP?
>

Yes, now I'm studying the effects of the raw communication on a
point-to-point connection. I have two testing nodes disconnected from the
rest of the cluster and connected one each other with a point-to-point
connection. The two nodes are P4 pentium with gigaethernet NICs by intel.
The driver I'm using is e1000-5.2.51 and the kernel version is 2.6.7
recompiled in order to non-add everything that isn't useful for my
experiments. Of course I've reliability problems because raw ethernet is
very useful to increase throughput and to send data as faster as possible,
but it's not tcp.

> Sounds like a lovely project.

Yes, it's very interesting

> Why don't you report to the list once a
> month or so.

No problem, I can report my results also once one or two weeks if someone
is interested and if I have news :-)

> Just remember, while you can likely skip the IP part
> (which is primarily associated with name resolution and routing) and can
> maybe skip the port part (dedicated function packets) you'll still have
> the rest of TCP to recreate -- reliable packet transmission and
> sequencing and checksumming.  Pretty ambitious, if you're planning to
> write the whole communications stack yourself (but yes, a great learning
> project).
>

Now I'll try to find a stable situation wich lets me have a good
throughput with very little frame-loss (so interrupt coalescence, NAPI,
e1000 params tuning and so on)
I don't know if someone else is making my studies but I would like to
share ideas (in internet I didn't found many news about raw ethernet, so I
think that is a quite new mechanism, interesting to develop)


Simone Saravalli
University of physics - Ferrara - Italy