Hello, I plane to built a system with a niosII mmu and linux on an Cyclone III device. I will use an IP ethernet core with an dp83848 phy. I need to use ethernet TCP communication. What is the maximum speed of data throughput I could hope to get? What MAC IP should I use?

There are already several threads om this issue in this forum (perhaps some of them, were lost in the biog crash year ago). AFAIR, the max throughput found was about 1-5 MByte/sec for a 100 MHz CPU without MMU. No idea if his will be greatly better or worse if you use an MMU. I doubt that the MAC or PHY hardware makes a big difference. -Michael

Thanks for answering, I have read the other thread and found the information you've give. This information is not realy coherent with the avaibility of Gigabit IP core. What is the use of such IP core? What is the real advantage of using fpga in place of CPU (i curently use ATOM processor with gigabit lan communication) if the performance are lower with an higher price: An ATOM processor + an intel 82574 is cheaper than a medium class fpga supporting GBit lan. There something I have missed?

In fact i'm thinking to use MMU only for supporting Linux in place of µLinux. I'm thinking to use something like a DMA controler to improve the data rate, that's why I was asking about the best MAC ip core.

See my thread on this here: http://www.alteraforum.com/forum/showthread.php?t=18934 There's a link or two to other useful threads there too. So far ethernet performance with a gigabit PHY (DP83865) can best be described as disappointing. I haven't been able to get it to work correctly at gigabit speed, so my results should be comparable to the DP83848. I am getting at best 38Mbit/s UDP with 1KB messages and 30Mbit/s TCP with the following tweaks: - altera_tse.c (SLS) driver for the altera TSE MAC - 32KB processor caches - a bunch of network related kernel functions in SSRAM instead of DDR DRAM - no cache burst - MMU (similar results without it) I am also seeing some unexplained dropped packets. Note that at least one other person in the thread has been able to get hundreds of Mbit/s with a similar setup, though they weren't using Linux.

An FPGA can provide superior ethernet throughput to a processor. However, the NIOS processor is not a high-speed processor. There is essentially no way it can keep up with an atom processor with regards to performance. If the sole purpose for your product is ethernet and you need a processor, a stand-alone processor is a better fit than an FPGA. Jake

Maximum ethernet speed available with NiosII + Linux

16 Replies

Altera_Forum
Honored Contributor
16 years ago
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We DMA from and adc data directly into a zero copy buffer and DMA straight out. We also use a HDL checksum component.
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In your case what is your best data rate?
Altera_Forum
Honored Contributor
16 years ago
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OK, so jumbo frame will change nothing.
Work is to do in the software/driver part. I'm correct?
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Software, yes. Driver, not so much. A relatively small part of the time it takes to send a packet from an application is the time spent in driver code.
Altera_Forum
Honored Contributor
16 years ago
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The iniche stack does provide a zero copy interface.
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I don't suppose this works together with Linux system (the theme of this forum).

Of course it should be possible to implement a dual NIOS system, one with niche, one with Linux.

-Michael
Altera_Forum
Honored Contributor
16 years ago
I am also interested in knowing the results of how the performance changes with tcp zero_copy enabled. I am currently seeing no difference, so I am wondering if I have something else set that is disabling it.

jcnhal - Any chance you can post the difference in performance you are seeing?
Altera_Forum
Honored Contributor
16 years ago
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with tcp zero_copy enabled. I am currently seeing no difference,
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How did you "enable zero copy" with Linux ?
I decently doubt that this is easily possible. You need to (1) port a zero-copy IP stack to NIOS and (2) create a zero-copy enabled Ethernet driver vor yo9ur hardware.

-Michael
Altera_Forum
Honored Contributor
16 years ago
Sorry Michael, I was doing this in Windows with the 9.1 software...
I mixed two points of conversation and shouldn't have done that for confusion's sake and been a bit clearer. I am interested in just finding out the maximum performance using TCP that anyone has been able to achieve.

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Maximum ethernet speed available with NiosII + Linux

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