Date: Wed, 29 Jan 2014 11:14:36 -0500
From:
address@hidden
To:
address@hidden
Subject: Re: [lwip-users] lwip with fatfs on a STM32 speed
problem
Yeah, the problem is not
lwIP! I'm using an M3 at 120MHz, and have megabit
performance. So optimizing how you fill buffers is a
waste of time. As Krzysztof pointed out, you need to
find the real cause of the slow behavior and fix that.
Try sending a pre-packaged chunk from flash or sram.
Have you verified that
Nagle's Algorithm is not hindering? If Nagle is on (at
the non-lwIP end), it throttles back to like five
packets per second. Put Wireshark
on the wire somewhere and see the spacing of the
packets.
I'm pretty sure Nagle's
Algorithm is off by default in lwIP. I don't recall
actively turning it off, but it is not happening in our
lwIP stack.
Marty
I do not currently have my code / project in
front of me, but I was reading some of the lwip docs and I
had a question on the tcp_write usage.
Is it OK to loop a function with tcp_write and tcp_sndbuf
(to check when full) in order to fill the write buffer with
data from the SD card?
Could I run a loop like this every time the tcp_sent
callback is called?
Would this increase speed?
Thanks
Dave
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