Re: [lwip-users] TCP transfer speed with Xilinx lwip_v3_00_a (lwip-1.2.0)

[Siva Velusamy]

On Jan 7, 2008 4:49 PM, Nathan Sam <address@hidden> wrote:

Hi,

This is regarding the lwipopts file for a TCP server running on Virtex-4.

I am hitting a very  low 100 KB/sec speed.

(1) It is a very simple client-server program based on SOCKET based API.
(2) Virtex4-PPC is the (SERVER) running Xilinx lwip_v3_00_a (lwip-1.2.0). Linux machine acts as a (CLIENT).
(3) Lot of memory (DDR) in the Server is available to be used for Lwip.

I need to transfer about 256 MB of data. Can anyone suggest if there is anything terribly wrong with my lwipopts file. I can understand that Socket API has some performance limitation (compared to Raw API), but I guess it should be better than 100 KB/sec.

Hi Nathan -

This is a limitation in Xilinx socket layer adapter (which I wrote). Here are some details.

The RAW mode is quite stable and provides ~ 100 Mbps.
The socket mode performance is < 1 Mbps. 

I've seen that the socket mode can achieve around 30Mbps, however at such throughput, the system eventually lands up in an unusable state. This is due to an as yet unresolved bug in either xilkernel or in lwIP sockets. Once this is resolved, we should be able to remove the workaround and achieve consistent throughput of ~ 30 Mbps (hopefully).

I expect this to be fixed in a subsequent release, most likely after the lwip 1.3.0 release.

Until then, I'd recommend using the RAW mode if performance is the main concern.

-Siva