Re: [lwip-users] TCP Raw API questions about efficiency and threads

[Sergio R. Caprile]

I think Noam has probably already said all that there is to say about 
the RAW API.
It is single thread only, and that includes your frame reception. All 
function calls to lwip must be on the same thread.
The ping response is immediate as a consequence of ping reception at 
packet processing, so the delay you see is the ability of your task to 
process the incoming frames in due time. Frame extraction is your 
business, lwIP is event driven, you give it your frame and it unwraps 
protocol by protocol until it delivers the payload to a callback 
function or answers back to the sender (if applicable).
Some people (read vendors) forget to extract ALL frames from the 
ethernet controller. Others have a priority issue. Others simply think 
that polling every 100ms is enough. Search the list for tips on your OS 
or search your OS forums for tips on lwIP. Check your driver, check your 
port.