BCM5704 performance questions.

[Ben Greear <greearb@candelatech.com>]

Hello!

I have a 4-port NIC by silicom-usa.com that uses the BCM5704 (rev 10) chipset.

It's running in a PCI-X bus (100 or 133Mhz).  CPUs are dual xeon 2.8Ghz,
1MB cache, 1GB RAM, etc).  Kernel is 2.6.11 + my hacks (no hacks to tg3, minor
hacks to e1000 and other parts of the networking stacks).

I am trying to bridge as much traffic as possible across two interfaces,
using a proprietary kernel module.
The network traffic is 1514 byte packets, generated by a modified version of
pktgen running on another machine with similar hardware (Intel NICs).

With the BCM NIC I can get about 600Mbps in one direction and about 800Mbps
in the other..with a great deal of dropped packets.  With the Intel 4-port
NIC (same machine, different PCI slot, and also from Silicom-usa.com)
I can get 900+Mbps in both directions with virtually no drops.

So:

*  Is the BCM5704 chipset/driver really that much slower?

*  Is there some information on tuning the tg3 somewhere?
    (I didn't see a Documentation/networking/tg3.txt file, for instance)

*  Is there a way to verify the bus speed that the NIC is running at?
    (ethtool -d ethX gives lots of meaningless (to me) hex)

Please let me know if more information would be useful.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com