RE: Multia UDB Hardware Questions

Shane Anderson (shane@nve.com)
Tue, 19 Nov 1996 19:03:05 -0500

On 19 Nov 96 at 15:31, Steven W. Decato wrote:

> Our tests involved 2 Pentium 100 machines running Linux 2.10 wired directly to
> each other via a crossover cable (send->receive, receive->send) "point-to-point".
> Using the crossover cable, no other machines are on the network, so traffic is
> not a consideration. We used 3COM595 100BT cards PCI cards. The software simply
> transmitted packets of various sizes and measured performance. We tested using
> straight sockets and MPI. Our tests revealed a maximum throughput of 2.5 megabytes
> per second. However, we noted that CPU load was nearly 100% so the assumption is
> that the process is CPU bound. We will do more testing to determine if a faster
> CPU will give faster performance. If so, how much faster? We also have a dual
> Pentium machine we will be doing testing on. Another variable to consider is the
> card itself. PC magazine noted in a recent article that the 595 cards do have a
> tendency to load down the CPU. I suspect this is why 3COM is now selling the
> Etherlink XL 10/100 cards (3COM-905TX).

I believe Alan Cox detailed the difference between the 3COM and DEC
PCI ethernets. If I recall correctly, the 3COM is bus-mastering but
the memory range was so limited (for DMA) that it was a real hassle
to keep packets moving--lots of CPU intervention... The DEC chip
21140 or whatever (and the other DEC chips) didn't have these
limitations so back to back packets were a lot easier and less CPU
intensive.

But I'm no expert and maybe some of the newer 3COMs don't have the
same problems... Check the Linux Networking pages for more accurate
details.

=Shane Anderson===========Nonvolatile Electronics, Inc.===
E-Mail: shane@nve.com Work Phone: (612) 996-1618
====================================http://www.nve.com/===

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