FEC performance on the 855T/860T

[Graham Stoney]

Hi gang,

Thanks to all your help, our custom 855T hardware is now up and running, and
it's time to do some system profiling & tuning. The first bottleneck to stand
out is that the FEC port isn't going as fast as we'd like. A simple socket
based tcp client/server setup which repeatedly send's from another machine and
simply recv's data without processing it in user space at all only gets just
over 3 Mbytes/s between two machines connected via a 100 Mbps switch.

There was some discussion on the mailing list last December regarding FEC
throughput on the 860T. For example, see:
    http://lists.linuxppc.org/listarcs/linuxppc-embedded/199912/msg00061.html

Our Embedded Planet CLLF860T boards fair even worse, getting around
2.7 Mbytes/s over the FEC, which tells me that it's not a problem with our
hardware. This is less than a third of its theoretical peak, and I'm
wondering if anyone has had a closer look at where the bottleneck with the
FEC lies?

Regards,
Graham
--
Graham Stoney
Principal Hardware/Software Engineer
Canon Information Systems Research Australia
Ph: +61 2 9805 2909  Fax: +61 2 9805 2929

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