Re: [lwip-users] Re: Sending too slow.

[Kieran Mansley]

On Tue, 2006-09-12 at 23:46 +0200, Mateusz Plocinski wrote:
> Well, it looks like TCP_NODELAY is used only in functions
> setsockapt
> getsockapt
> They are probably available for user as TCP_NODELAY is described in tcp.h:
> /*
>  * User-settable options (used with setsockopt).
>  */

If you're using the raw API, then there is no Nagle algorithm - it's
implemented in api_msg.c which is one of the higher layered APIs.  Did
you try looking at the loop in tcp_output() to see why it's not sending
more packets?

> Someone has written in older topic that this problem is connected with lack 
> of free memory. I can imagine the following situation: lwIP doesnt send next 
> packet because it dont have free memory and it has to wait for ACK for last 
> packet to free its memory and then load a new packet into buffer.
> At this state of knowledge I'm not able to check it, but I'll keep lerning 
> lwip code and trying.

If you compile with PBUF_STATS defined to 1 the stack will keep track of
how many free buffers there are, and you can then print this information
out at relevant points by adding suitable code where you need it.

Kieran