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[EDK] XilNet throughput

Hello all,

I'm using the XilNet library on a Virtex-II Pro (PPC), and my objective is to send quite large amounts of data via an external MAC/PHY (SMSC

91c111) to a computer running Windows XP. The server application on the PPC is quite simple, it waits for the client to connect and then it starts streaming the data as fast as the PC is able to receive it. The protocol used is TCP.

The throughput is very poor, about 800 kbps at the moment. And I can't really figure out why. Using Ethereal I have seen that it takes about 15 ms for the PC to acknowledge the data packages from the FPGA, while the ACKs from the FPGA is sent much quicker. Every once in a while, though, the ACK is sent directly after received data packet.

Has anyone seen similar symptoms with XilNet? Should I swap to LwIP instead? How much work (approximately) is needed to port LwIP to work with an external MAC/PHY chip? Not very surprisingly Xilinx only provide ports to theirs own MAC IPs. The reason I used XilNet in the first place is that I'm in a bit of time shortage... Also, I have no external memory, would it be possible to run XMK and LwIP from BRAM on a Virtex-II Pro-40?

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Johan Bernspång, xjohbex@xfoix.se
Research engineer

Swedish Defense Research Agency - FOI
Division of Command & Control Systems
Department of Electronic Warfare Systems

www.foi.se

Please remove the x's in the email address if
replying to me personally.
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Reply to
Johan Bernspång
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Talk to a software/networking geek.

Lots of people have worked on making TCP go faster. It's not a simple problem - too many special cases.

As a sanity check, you should run your PC against a handy web server and compare the speed and packet traces.

My guess is that the TCP implementation on your PPC is dumb/simple and only allowing one un-ACKed packet at a time. That works, but won't go fast unless the other end cooperates. It makes the software a lot simpler.

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Reply to
Hal Murray

Hal Murray wrote: > My guess is that the TCP implementation on your PPC is

That is my feeling too, I'll give LwIP a chance when time permits. Xilnet is quite under developed, and that is a fact.

/Johan

--
-----------------------------------------------
Johan Bernspång, xjohbex@xfoix.se
Research engineer

Swedish Defense Research Agency - FOI
Division of Command & Control Systems
Department of Electronic Warfare Systems

www.foi.se

Please remove the x's in the email address if
replying to me personally.
-----------------------------------------------
Reply to
Johan Bernspång

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