can EP2C35+Nios+DM9000 provide 50Mbps throughput?

Hello Haishan,

I think, the "Ethernet Acceleration Example" can help to understand the system characteristics that limit network throughput, although it uses different network controller and OS than you do. The benchmark data from AN440 give a general idea of what could be expected. It seems to indicate, that besides data processing within the TCP stack (e. g. calculating checksums) also network processor interface (in case of LAN91C111 that should be roughly comparable with DM9000) could be a bottleneck. This is somewhat surprizing, cause these devices can transfer data at network speed to and from conventional processors.

If the DM9000 interface shows similar behaviour as the LAN91C111, the intended 50 MBps seem unattainable. I also wonder, if uClinux could be easily modified to use hardware acceleration and the said "zero copy" operation. It may be easier to design a "hardware" TCP socket independent of Nios and uClinux.

Best regards,

Frank