Re: [lwip-users] Get max throughput UDP handling

[Patrick Klos]

On 10/9/2020 5:02 AM, Mário Luzeiro wrote:
> Hello all,
>
> I'm sending UDP messages sequential, at "full speed" from a PC to a MCU (using 
> Lwip)
> I know I'm loosing some UDP messages (I implemented a sequential counter to 
> debug it)
>
> the udp_recv_fn is doing nothing much and exists almost immediately.
>
> Is it expecting that I lost packages due the CPU performance? (considering that 
> packages are not lost by other cases)
> or how do I know if I have enough CPU power that can handle max communication 
> rate?
>
> What can I do in LwIP to handle more packages and don't get it lost, any 
> configurations I should look at?
>
> Mario

Hi Mario,

I presume your MCU's ethernet is 100 Mbps?  Is it connected directly to 
the PC via ethernet or are they both connected to a switch?  If a 
switch, what speed is the PC connection to the switch versus the MCU 
connection?  If the PC is 1 Gbps and the MCU is 100 Mbps, your MCU will 
never be able to keep up.  What percentage of packet loss are you seeing?

How many packets per second (and what size) are you calling "full 
speed"?  I've found the LwIP stack on the Tiva was quite reliable and 
robust enough to support very high speed reception of UDP packets.  I 
usually queue up the received pbuf's to be processed in the "foreground" 
for best results (unless your processing of the UDP packets is truly 
minimal?).

Patrick