Re: [lwip-users] MEMP_NUM_TCP_SEG setting

[Siva Velusamy]

the send queue leaving none for receive).  Assuming all your segments
are full size and the same settings are used at both ends, the total
number of segments required will be:

   (TCP_WND + TCP_SND_BUF) / TCP_MSS

Kieran

Thanks, that was it. On the host I was using iperf which used a 85K window size by default. So now I can get past this. But unfortunately, there is still an error, and there are two symptoms, which may be because of to 2 different problems:

1. After some random interval, a timer interrupt happens -> calls tcp_output -> goes to this loop:
  /* useg should point to last segment on unacked queue */
  useg = pcb->unacked;
  if (useg != NULL) {
    for (; useg->next != NULL; useg = useg->next);
  }

This loop happens to be circular! Should I assume that I'm calling some lwip tcp function from a context that has not been properly guarded with mutexes?

2. The second issue that I see (if I don't run into issue 1), is that the TX performance keeps dropping slowly. Over 10 minutes it drops about 10 Mbps or so..starting from lets say 55 Mbps to 45 Mbps, and continuing to drop. Any suggestions on what to look for here? Could it be that my timer interval is not quite right?

Thanks,
-Siva