8260 IDMA experience?

[Allen Curtis]

> I have been using IDMA to transfer data between kernel memory and a
> FPGA. I also did some testing with memory-to-memory transfers and i
> didn't find them to be worth the trouble. Performance ain't that great.
> You probably get more speed by copying with your CPU, though you might
> avoid some cache trashing.

So it works but it may not be as fast as a memcpy(). Sounds like more
testing is required to determine the overall benefit of freeing the
processor.

> I did also notice that when i am doing memory-to-peripheral (or
> vice-versa) transfers, IDMA corrupts simultaneous Ethernet traffic
> unless IDMA is set to low-priority mode. Same might apply for
> memory-to-memory transfers.

What 8260 chip revision are you using? I have found lots of problems when
rev A processors but rev C has been much better.


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