Re: [lwip-users] Can I tune the retransmit configuration?

[Kieran Mansley]

On Mon, 2010-11-22 at 13:29 -0500, Chen wrote:
> Can lwip be configured like this?

In part, yes.  lwIP will keep transmitting as long as it is allowed to
by TCP.  There are three things that control this:

1) The advertised receive window by the receiver, and how much has been
used already.
2) The current congestion window, and how much has been used already
3) The availability of data to send from the application.

1) is controlled by the TCP_WND define in lwipopts.h, although it sounds
in your case like lwIP is not the receiver but the sender, so this
shouldn't be necessary.

2) is not configurable.  

3) is controlled by TCP_SND_WND in lwipopts.h, and depends on the
application providing the stack with enough data.

There is also Nagle's algorithm that may affect your ability to send.
You could try running with the NODELAY socket option set and see if that
helps.

Kieran