Hi All, 

I'm currently testing our hardware with lwip 1.4.1, and I see a big
performance difference between using Netconn API and the RAW api.
For baseline I have used the LPCopen sample 'TCP echo Standalone' and 'TCP
echo FreeRTOS' demo's.

I have re-written the demos to connect to a server application on the
laptop, The server application sends data with different package sizes and
excpect the same data returned. The roundtrip is measured.

The stack, in two samples, are setup as similar as possible in the lwipopt.h
file. The target hardware is the same, just as the network and test PC.
Nagle is dislabled.
Also the low-level EMAC driver for the MCU are the same.

With FreeRTOS and Netconn, the trohugput is poor with larger packages (>128
bytes). Sometimes the roundtrip for a package is mores than 2 seconds (It
seems yo be in the netconn_write). Sometime it stalls, when the server
application sends packages to fast after each other.
With the RAW api standalone demo there are no problems at all. Good through
put. 
I than tried to run the RAW TCP demo in FreeRTOS enviorenment. No problems
here.

Because the RAW TCP demo work fine, I assume the low level EMAC driver for
the LPC17xx are working ok.
Because the RAW TCP sample works fine wtih FreeRTOS I assume that works fine
too.

Any other Idea's why this? Or things I could try?

Somehow the combination of LPC17xx and Netconn seems to be a bad choice.!??
(Using google I can see Im not the only one strugling with lwip and LPC17xx)

I will try to updgrade my test sample with the latest lwip 2.0 to see if
that somehow helps.

If not, I think I will revert to using the RAW TCP in my user application
and droppping Netconn API

Thomas





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