Re: [lwip-users] lwIP delays outgoing TCP packets by up to 500ms

[Pîrvu Mihai]

I've worked around this disabling Nagle Algorithm for each pcb and also calling tcp_output after every write. But somebody told me it was the wrong approach doing so, but it works for me so I don't know what to say.

Mihai

On Wed, Jul 13, 2016 at 3:20 AM, Jakub Schmidtke <address@hidden> wrote:

Hi,

I am using lwip with NO_SYS=1, and I have noticed

that outgoing TCP packets are very delayed.

It looks like between writing a packet (using tcp_write),

and the time it actually written to the interface it takes usually about 200ms.

I examined the code, and it looks like lwip only writes regular packets every 500ms.

Basically tcp_write only adds segments to a list, and they are only actually sent inside tcp_slowtmr.

Which, by default, is only called once every two calls to tcp_tmr().

Which gets called every 250ms, so the data being written with tcp_write will be sent out up to 500ms later.

This is a really, really long time!

Am I missing something?

Thanks!

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