RE: [lwip-users] Intention of poll, tcp_output() in tcp_slowtmr() call.

[David Aldrich]

Hi Robert

> David, in my case, I am using the "raw" interface, the one 
> with callbacks.  Sounds like you are doing that as well.  
> My application creates output in the form of "messages", 
> and sends them with tcp_write() once they are 
> ready to transmit. It was my assumption that the reason 
> output is not sent immediately based on a call to 
> tcp_write() is because it may be that two 
> or more packets could be combined, and therefore sent more 
> efficiently.  
> 
> This strategy makes sense for an application like ftpd, or 
> even httpd, where traffic is not very interactive, but 
> works poorly for something like telnetd.  
> 
> My solution was to call tcp_output() directly for each call 
> to tcp_write() unless the call to tcp_write returned an error.

Thanks for your reply.  Yes, I am using the raw api.  I agree with your
conclusions and I now call tcp_output() directly for each call to
tcp_write(), as you suggested.  I also combine small messages at my
application layer, so this scheme works well for me.

Best regards

David