[En-Nut-Discussion] Ethernut TCP hangs

[Dusan Ferbas]

Hi Michael,

I prefer more info instead of plenty of source code. First - what about 
ethernet traffic on your LAN segment ? Are there a lot of ARPs ? Even 
collisions ?

If yes I suggest to use following modification. It allows other threads to 
run instead of continuously serving incoming packet storm. We found this 
critical.

This mechanism follows what I discovered usefull with other embedded 
cooperative OS where ethernet packets are served via a separate thread. 
This was necessary even when run on 32-bit 66MHz chip with integrated (i.e. 
DMA into RAM) ethernet controller.

Please keep me informed if this modification helps.

--------------

>     //JS
>     unsigned long end_tick_count;
>     //JS
...
>         while (1) {
>         NutEventWait(&ni->ni_rx_rdy, 0);
>
>         //JS 7/1/2005
>        #define MAX_RECEIVING_TIME      100     //ms
>         end_tick_count = NutGetTickCount() + (MAX_RECEIVING_TIME*2)/125;
>         //JS
>         /*
>          * Fetch all packets from the NIC's internal
>          * buffer and pass them to the registered handler.
>          */
>         do {
>
>             nb = NicGetPacket();
>
>             /* The sanity check may fail because the controller is too busy.
>                restart the NIC. */
>             if ((u_short) nb == 0xFFFF) {
>                 NicStart(ifn->if_mac);
>                 ni->ni_rx_size_errors++;
>             } else if (nb) {
>                 ni->ni_rx_packets++;
>                 (*ifn->if_recv) (dev, nb);
>             }
>     #if 1
>             //JS 7/1/2005
>             if ((NutGetTickCount() >= end_tick_count))
>             {
>                 NutThreadYield();
>                 end_tick_count = NutGetTickCount() + 
> (MAX_RECEIVING_TIME*2)/125;
>//                putchar('@');
>             }
>
>         } while (nb && (NutGetTickCount() < end_tick_count));
>     #else
>         // original
>         } while (nb);
>     #endif

---------------
>From: "Michael Smola" <Michael.Smola at gmx.net>
>Subject: RE: [En-Nut-Discussion] Ethernut TCP hangs
>
>New information on TCP stalls:
>
>I discovered, that with 3.9.5 only the last two http threads are activated
>(3&4 in case of 4 http threads, 7&8 in case of 8 http threads).
>With 3.4.1 the threads are permuted as expected from 1 to 4 (8).
>
>After a while, only the last thread is activated. Maybe later the 4th
>thread is stalling too!?



Dusan