Re: [lwip-users] lwIP RAW - Low throughput during first few seconds

[Nenad Pekez]

Hi Simon,

these are steps I have taken in order to investigate this problem:

• Wireshark capture - there is basically no packet exchange for 5 seconds or so (ws_cap0.png),
• displaying lwip stats for ip, link, tcp and mem - no errors or anything unusual was observed (lwip_ip_stats.log, lwip_link_stats.log and lwip_tcp_mem_stats.log) and
• displaying lwip debug information for tcp - what I noticed is that once state becomes ESTABLISHED, two more packets are received and than outputs from tcp_slowtmr function are displayed several times in a row: "processing active pcb" and "polling application". 

What these outputs mean, can someone explain me? Since tcp_slowtmr should be called every 500ms, there is at least 3 seconds of pause there.

I have also turned lwip netif debug, but no errors are reported. I am using Xilinx drivers, so I am still trying to figure out is there a way to print some debug options from that layer.

Oh, I forgot to say that we are using lwip 1.4.1. Also, I didn't notice this problem when we test throughput in opposite direction, sending data from Zynq to PC (if that means anything).

Best regards,
Nenad

P.S. I can send entire Wireshark capture, but it is quite large, maybe there is some practical way to upload entire capture?

ws_cap0.png
Description: PNG image

lwip_ip_stats.log
Description: Text document

lwip_link_stats.log
Description: Text document

lwip_tcp_mem_stats.log
Description: Text document

lwip_tcp_dbg.log
Description: Binary data