Re: [lwip-users] Low Iperf performance of lwip 1.4.1 on STM32 and FreeRTOS

[ella]

The problem is not FreeRTOS but buggy and ugly STM32 netif driver. I have
studied original driver provided by ST and had nothing but rewrite it.  

Just one example of wrong architecture of this driver. This is from
low_level_output():

    buffer =  (u8 *)(DMATxDescToSet->Buffer1Addr);
    for(q = p; q != NULL; q = q->next)
    {
      memcpy((u8_t*)&buffer[l], q->payload, q->len);
      l = l + q->len;
    }

Consider that buffers are allocated as 
extern uint8_t Tx_Buff[ETH_TXBUFNB][ETH_TX_BUF_SIZE];
and are linked to chained DMA descriptors.

If packet size bigger then ETH_TX_BUF_SIZE you are at potential danger of
wrap around that is not treated in code. Same happens for RX flow. So no
surprise you have a problems with big packets.
And this is only one place, there is a number of others. There are also a
few races.
In short DO NOT USE THIS DRIVER. 





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