[tulip] Tuning the tulip, or Good Channel bonding NICS under Linux?

[Camm Maguire]

Greetings!  We've been experimenting with channel bonding a bit, and
have noticed some major performance differences with brand of NIC (of
course).  So far, we've tried Netgear FA310tx, which the Lite-on
82C168 chip, and Intel Etherexpress pro100, with Intel 82557 chips.

In sum, the latter reaches almost 2x the former on netpipe TCP
benchmarks for large packet sizes.  As the packet size gets big, the
Netgears overrun the fifos a few times, causing the driver
(apparently) to backoff on the throughput.  On 2 full-duplex 100Mbps
channels, running NPtcp both ways simultaneously between two hosts,
the Netgears go up slightly above 100Mbps at some packet size, and
then backoff to around 80 Mbps, whereas the eepro100's go right on up
to about 130Mbps without fifo overruns.

1)  Is there anything I can do to the various tulip drivers to fix the
    overrun issue, or is this in the hardware?
2)  Anyone have a good recommendation for NICS for this setup
    (bang/buck?)  I thought we'd get a lot closer to 200 Mbps.  We do
    get to about 180 when transmitting only in one direction at a
    time.

Thanks!


-- 
Camm Maguire			     			camm@enhanced.com
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"The earth is but one country, and mankind its citizens."  --  Baha'u'llah