Re: [lwip-users] Re: tx badnwidth

[Kieran Mansley]

On Wed, 2009-03-04 at 14:09 -0500, Chen wrote:
> http://www.dataq.com/chen/lwip_tx.zip is the capture file you asked
> for.
> 
> From the capture, you can see the tx frequency drops dramatically:
> 100-byte payload: tx 631 packets per second, with packet sizes mostly
> in 100 and 700 bytes
> 2048-byte payload: 5 packets per second, and the packet sizes are
> between 690 to 1460 bytes

The reason the 2048-byte payload one is going so slowly is because it's
waiting for the ACK from the other end before sending each packet.  The
other end is delaying ACKs (as it should) and so there is a big gap
between packets.  Normally this indicates too small a TCP window or send
queue.  Can you show us your lwipopts.h settings?

When sending lots of small packets it's not a problem because you get
lots of ACKs back, and so it doesn't wait as long.

Thanks

Kieran