Poor performance with LWIP and uCOSII on NIOSII

Hi there,

I'm using a niosii system using data (2kb) and instruction cache (4kb) and running ucosii and lwip, and based on an ip gbethernet mac core.

With a very simple (and stupid ...) application, I benchmark the overall performance of this system with a UDP streaming.

The first results concern me a lot:

globally the low level (Interrupt handler, home made driver and VHDL IP core) runs quite well :

interrupt latency => 7usec

delay in the interrupt delay in (Transmission mode) => 6usec

DMA transfert => 10,6usec (for 1024 bytes)

however, even with a simple loop at the application level to send a given number of udp packets (no superfluous job), the first results give me a maximum throughput about 5-6 mbits/sec which is very low.

Does someone have any figure to confirm or to invalidate my results with an equivalent system ?

Thanks in advance.

Gaël