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

[Dave Nadler]

Thanks Simon. The FreeRTOS tic is running at 1mSec.

Test setup is laptop and Nucleo on my desk with hub, so round-trip should be fast, no?

What other timers could be involved?
Where should I look for LwIP <-> low-level timer setup/use?
Possibly ST's implementation is sub-optimal.

Thanks for the help,
Best Regards, Dave

On 2/28/2019 1:09 PM, address@hidden wrote:

Am 28.02.2019 um 17:42 schrieb Dave Nadler:

I naively expected that after receiving the" duplicate ack" signalling a packet dropped,
LwIP would immediately re-transmit the dropped packet.

No, TCP fast retransmission starts after 3 dupacks only.

Instead there is a 1.5 second pause (see Wireshark trace below).
Why is that?

Yeah, that's a little strange. I would have expected ~250ms for the RTO retransmission,
but then again, it depends on your roundtrip time.
But it could well be 1.5 seconds because your timers are not coming at the expected interval?

Regards,
Simon
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Dave Nadler, USA East Coast voice (978) 263-0097, address@hidden, Skype 
 Dave.Nadler1