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[lwip-users] R: socket slow down


From: Rastislav Uhrin
Subject: [lwip-users] R: socket slow down
Date: Fri, 20 May 2016 14:29:37 +0200

Hello Jens,

I am still on this problem.

Yes. I have interrupt and I have semaphore. See bellow.

But what can be wrong?  How do I detect that packets are behind?

Thanks a lot

Rastislav


Interrupt
void ETH0_0_IRQHandler(void)
{
  uint32_t status;

  status = XMC_ETH_MAC_GetEventStatus(&eth_mac);

  if (status & XMC_ETH_MAC_EVENT_RECEIVE)
  {
    sys_sem_signal_isr(&eth_rx_semaphore);
  }

  XMC_ETH_MAC_ClearEventStatus(&eth_mac, status);

}

Task waiting on semaphore
static void
ethernetif_input(void *arg)
{
  struct pbuf *p = NULL;
  struct eth_hdr *ethhdr;
  struct netif *netif = (struct netif *)arg;

  while(1)
  {
    sys_arch_sem_wait(&eth_rx_semaphore, 0);

    p = low_level_input();

    if (p != NULL)
    {
                 ethhdr = p->payload;
                 switch (htons(ethhdr->type))
                 {
                   case ETHTYPE_IP:
                  case ETHTYPE_ARP:
                     /* full packet send to tcpip_thread to process */
          if (netif->input( p, netif) != ERR_OK)
          {
            pbuf_free(p);
          }

          break;

                   default:
                     pbuf_free(p);
                     break;
                 }
    }
  }
}

Input processing
static struct pbuf *
low_level_input(void)
{
  struct pbuf *p = NULL;
  struct pbuf *q;
  uint32_t len;

  len = XMC_ETH_MAC_GetRxFrameSize(&eth_mac);

#if ETH_PAD_SIZE
  len += ETH_PAD_SIZE;    /* allow room for Ethernet padding */
#endif

  if (len < XMC_ETH_MAC_BUF_SIZE)
  {

    /* We allocate a pbuf chain of pbufs from the pool. */
    p = pbuf_alloc(PBUF_RAW, len, PBUF_POOL);
  
    if (p != NULL)
    {
#if ETH_PAD_SIZE
      pbuf_header(p, -ETH_PAD_SIZE);  /* drop the padding word */
#endif

      XMC_ETH_MAC_ReadFrame(&eth_mac, buffer, len);

      len = 0;
      /* We iterate over the pbuf chain until we have read the entire
       * packet into the pbuf. */
      for (q = p; q != NULL; q = q->next)
      {
        /* Read enough bytes to fill this pbuf in the chain. The
         * available data in the pbuf is given by the q->len
         * variable.
         * This does not necessarily have to be a memcpy, you can also 
preallocate
         * pbufs for a DMA-enabled MAC and after receiving truncate it to the
         * actually received size. In this case, ensure the tot_len member of 
the
         * pbuf is the sum of the chained pbuf len members.
         */
         memcpy(q->payload, &buffer[len], q->len);
         len += q->len;
      }

#if ETH_PAD_SIZE
      pbuf_header(p, ETH_PAD_SIZE);    /* Reclaim the padding word */
#endif

    }
    else
    {
      XMC_ETH_MAC_ReadFrame(&eth_mac, NULL, 0);
    }
  }
  else
  {
    XMC_ETH_MAC_ReadFrame(&eth_mac, NULL, 0);
  }

  return p;  
}

-----Messaggio originale-----
Da: lwip-users [mailto:address@hidden Per conto di Jens Nielsen
Inviato: mercoledì 11 maggio 2016 16:52
A: address@hidden
Oggetto: Re: [lwip-users] socket slow down

Hi

If you search the list you will find a lot of people with the same question, 
it's impossible to tell where your packets are delayed without you doing some 
analysis (traces? breakpoints?) but one thing I can say for sure is that your 
problem is quite certainly not within lwip. A common error is to assume that 
one packet equals one interrupt which equals one signalled semaphore which 
equals one processed packet, whenever you receive a second packet before the 
previous is processed you'll be "one packet behind" and experience delays like 
you describe. 
Where did you get your driver?

Best regards
Jens


On 2016-05-11 12:42, Rastislav Uhrin wrote:
>
> Hello,
>
> I need advice and help on one issue with lwip stack version 1.4.1. I 
> am new to this stack and to networking in general. Nevertheless I have 
> integrated it to application on Infineon xmc processor together with 
> FreeRTOS.
>
> Looking on many different examples on the internet and many trial and 
> error. I am using netconn sockets. Application works!
>
> The only problem is that after some time, better say after exchanging 
> several 10-100 packets of different sizes, response gets slow. From 
> 2ms down to 2-3seconds. It still works but slow. Same if I use ping.
>
> I tried all possible setting of lwip options but of course since I 
> don't have deep insight of what they influence I was not able to 
> improve this behavior.
>
> I would appreciate if you can give me a hint what could be wrong, what 
> could I check, how to proceed to debug this strange behavior.
>
> I tried also new version 2.0 of stack but behavior is same.
>
> rum
>
>
>
> _______________________________________________
> lwip-users mailing list
> address@hidden
> https://lists.nongnu.org/mailman/listinfo/lwip-users


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