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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