[lwip-users] Re: Lwip UDP performance

[Reither Robert]

I'm using this ethernet hardware too and its sad but true, the device does only 
have 4 fixed size (receive) buffers.
So if u receive 4 packets very fast, the (hardware)buffers are full and the 
chip is dropping packets till u have read them out. i'm using DMA data 
transfers and got down to 85µs/packet that's my maximum interface throughput 
running NIOS cpu with 50Mhz (and its not trivial to use DMA with the 91c111, u 
have to serve the ARDY line or use max. Interface speed of 100ns cycle-time, 
and don't 4get to flush CPU data caches after DMA read)

Routing packets thought the stack will take much more time than, but if u have 
send-delays, u can process the packets from a buffer after the bursts.

Greetings
Robert

Hard/Software engineer
AV-Digital
Austria