CSR0 and Linksys cardbus performance at 100Mbps

Bruce Lowekamp lowekamp+@cs.cmu.edu
Mon Mar 1 19:37:16 1999

I just got a 100baseTX hub to connect my alpha workstation and laptop on
the same network, so I figured I would test the various register settings
for the Linksys cardbus 21143-TD card over my new link.

Summary: 0x00A0C000 is the best setting.  Under no circumstances enable WIE.

(this concurs with Nicholas Jenkin's measurements with ftp at 10Mbps)

Setup: TP600, 2.0.36, 3.0.9, .90q
    other end is a 500Mhz alpha with a tulip interface running DUX4.0c
    connected through a Netgear FE104 hub, attached directly to a switch
Measurement: ttcp using tcp, 50 1000000 byte messages, 120000 socket buffer
times were recorded on the receiving side

I played with a few settings with WIE set, but none of them came close to
full 100Mbps performance.  The maximum was about 20Mbps sending, 1Mbps

I tested 4 other settings: 0x00a0e000, 0x0020e000,0x00a0c000,0x0020c000
Five observations were made in each direction.

In all cases, data was received at 84Mbps.

Only 0x00A0C000 sent data at 84Mbps every time.
0x0020C000 sent data at 83Mbps once
0x0020E000 sent data at 83Mbps once and 80Mbps twice
0x00A0E000 sent data at 83Mbps twice.

Obviously there's very little difference between the settings.  I would
have to do more analysis (and record the data with more precision) to tell
if there's a real difference, but I'm going with the 0x00A0C000 setting.


Bruce Lowekamp                lowekamp@cs.cmu.edu