RE: [lwip-users] Optimizing TCP writes

[Bill Auerbach]

Thanks Jonathan,

I see that it outputs a segment in tcp_output, but I'm not calling
tcp_output.  I'm calling tcp_write multiple times.  I do see it append a
segment in tcp_enqueue.  Shouldn't tcp_output pass a linked pbuf chain with
enough data up to the MSS?  If I call tcp_write 10 times with 10 "Hello
World"s, I would think one Ethernet frame would be sent with a call to
ip_output with one pbuf pointer with 11 payloads (the header and 10 data
payloads).

Bill
 
> I believe tcp_output always outputs a segment. What tcp_output_nagle does
> is choose times _not_ to - i.e. to wait a bit and save it up. You can see
> if defined in include/lwip/tcp.h.
> 
> In other words, only call tcp_output when you do want to output something.
> And arguably the same for tcp_output_nagle (although it won't guarantee
> you
> will). Obviously you may need some care you don't keep enqueuing data and
> never sending it, until you run out of buffers!
> 
> Jifl
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