[eepro100] eepro100 and large packets

[Cagle, John]

This is just a guess, but if your app is really sending Ethernet packets
that are 65,000 bytes in length, then you're probably running into a
hardware limitation that's a combination of things.  First, the EE Pro/100
NIC's transmit and receive FIFOs are probably *much* smaller than 64K.
Second, since your FIFOs are much smaller than the packets you're trying to
send, your packet loss is probably caused by PCI bus latency.  Try using a
different PCI slot (one that's on a different PCI bus) and make sure you're
running at 33 Mhz.  Lastly, you might want to try using a machine with a
faster, more efficient bus architecture.

Regards,
John Cagle
Industry Standard Server Group
Compaq Computer Corporation
http://www.compaq.com/linux/

-----Original Message-----
From: Philip E. Varner [mailto:pev5b@cs.virginia.edu]
Sent: Tuesday, October 31, 2000 10:15 AM
To: eepro100@scyld.com
Subject: [eepro100] eepro100 and large packets

Where I work, our newest servers have eepro100 NICs.  They're running
kernel 2.2.14.  Our primary application uses packets 65000 bytes in length
for communication.  However, when sending large packets like this,
performance plummets at a packet size of around 64,590 bytes.  Below this,
I get minimal packet loss, but above this it jumps to around 50-70%
_loss_.

I've tried this on other machines (de4x5 driven) on the same switch and it
doesn't happen.  Has anybody seen this before?

Phil Varner