[lwip-users] [lwip] lwIP on Gigabit Ethernet

[Chris Borrelli]

Just putting some information out there..

I have a simple lwIP (0.5.3) echo application running on a gigabit
Ethernet network - no OS, no sockets API, just the raw lwIP API.  The
performance is much less than I thought it would be (~4Mb/sec).  Does
anyone have any comments/suggestions or "I told you so" about this?

The system that its running on is PPC405 @ 200Mhz with an on chip
Ethernet MAC (one of our own).  The bare metal performance of the system
(no tcp stack) is about 40Mb/sec - the MAC host interface and driver I
am working with is not at all optimized (16-bit interface @ 50Mhz, no
DMA, no interrupts...).  But adding lwIP drops the performance by 10x
(from 40 downto 4).  That doesn't seem right...

I took a look at the TCP stream.  It looks like host PC fills the window
(1024) of the lwIP device, and then the connection is reduced to sending
very very small tcp segments back and forth.

Has anyone else seen similar issues?  I get similar performance on a
100Mb/sec line (~4Kb/sec data rate).

Does anyone have any lwIP performance numbers for their applications???

 -Chris

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