Re: [lwip-users] TCP send queue and small windows

[Kieran Mansley]

On Tue, 2007-03-20 at 12:18 +0200, Vlad wrote:
> I've solved this by sending data with smaller chunks at a time ( i call 
> tcp_write with TCP_MSS bytes at a time ). unfortunately this slows down 
> uplink.

Hmm, I'm sceptical that this has really solved the problem you described
because the packets in the queues will be TCP_MSS bytes long whether or
not your application sends in TCP_MSS chunks or larger chunks.  It could
just be that because you have reduced the performance, the problem
doesn't occur in the first place (e.g. because sending slower you have
less loss so fewer retransmissions) and that your problem will come back
some time in the future.  I suggest trying my suggestion from yesterday
to see if that helps.  It should be a very quick and easy thing to try,
and won't impact your performance in this way.

> seems that this is issue with lwip, because i didn't see this problem with 
> windows tcp/ip at the same machine, connecting the same server.

But I guess you weren't tweaking the receive window on the windows
TCP/IP stack in the same way?

Kieran