[lwip-users] performance in sending / receiving

[Robert Goeffringmann]

Hi,

I got lwip to run on the ps2's main cpu and achieve send speeds of ~4 
Mbyte/s.
Unfortunately the speed for receiving data is stuck at ~1-2Mbyte/s and I 
can't figure out why...

In both cases, I run a very simple test app on the PS2 that simply opens a 
socket and calls send (or recv) in an endless loop over and over again with 
a 40Kbyte large buffer.

When receiving data, it always starts with lwip advertising a window of 
29-32KB, which is quickly filled by the host pc.
lwip then sends ACKs, reducing the window sizes until it finally sends a 
zero window..
Then, after a couple of millis, it sends a new window update with a size of 
29-32KB.

I already don't understand why it doesn't advertise a bigger window to begin 
with.
> From what I can tell my presets in the lwipopts.h are fairly big:

#define MEMP_NUM_PBUF          100
#define MEMP_NUM_TCP_SEG        100
#define PBUF_POOL_SIZE         200
#define PBUF_POOL_BUFSIZE       1580

#define TCP_MSS                 1460
#define TCP_SND_BUF             (TCP_MSS * 40)
#define TCP_SND_QUEUELEN  64
#define TCP_WND                 (TCP_MSS * 40)
#define TCP_SNDLOWAT  (TCP_SND_BUF/2)

Can't I usually expect to be able to achieve roughly the same rates for 
sending and receiving?
And.. did anyone ever manage to max out 100mbps entirely using lwip or is it 
too focused on being lightweight for that?

I uploaded my full lwipopts.h, excerpts from ethereal logs and lwip's stats 
output here...
http://www.goeffringmann.de/lwip/lwipopts.h
http://www.goeffringmann.de/lwip/recv_on_ps2_ethereal.txt
http://www.goeffringmann.de/lwip/recv_on_ps2_lwipstats.txt
http://www.goeffringmann.de/lwip/send_on_ps2_ethereal.txt
http://www.goeffringmann.de/lwip/send_on_ps2_lwipstats.txt
192.168.6.20 is my PC and 192.168.6.23 the PS2 running lwip.

Any help or starting point would be much appreciated.

Best regards and thanks a lot in advance,
Robert.