Re: [lwip-users] Throughput benchmark question - nasty ~1.5 second pauses

[Sergio R. Caprile]

If I were to debug this, I would use UDP, you can move a pin when
sending and be sure the msg will at least get to the driver (where we
think it is lost). TCP... well...
Then, every entry to the driver should end with a safe exit and due to
DMA a later "done" interrupt where the driver frees the buffer. (with no
DMA, the buffer is freed when sent to the chip and things are way simpler)

A driver framework is simple, but a DMA driver gets complicated. I would
try putting breakpoints at troublesome decision points and try to catch
errors or unexpected conditions.
I mean, most of the time frames go through, so something happens once in
a while; what is this that happens ? What can be ?
Is it copying memory to DMA ring buffers ?
Most of the times the driver should get an available ring buffer, what
happens when it doesn't ? Is it happening ?
I'd suggest asking for help in ST forums.
Good luck!