DMA ready - upload later today

[Peter Pregler]

Hi all,

I have finished coding DMA-mode transfer, i.e. my box did not crash since
I found the last serious bug. I will make a clean patch later today. This
e-mail is just here to stop all the DMA-coders all over the world from
further wasting their time. ;)

I hoped that DMA will increase frame-rate and thruput. But sad enough that
is not the case. That seems to be caused by some not yet tracked down
problem. I suspect the handshake or the camera setup. In any case, what
will DMA do/not do?

- reduces CPU-load on my machine (PII/330) from 60% to 10% for
  CIF/uncompressed operation :-)
- if someone is bored enough to code it decoding and datatransfer could now
  be parallelized, this might increase frame rate on slow CPUs
- is written with documentation about one specific io-chip. I have no idea
  if it works for other chip-sets as well. Actually, I have no idea
  what chip-set my computer uses. ;)
- is maybe Intel-specific, the code might not even compile on other
  architectures. But since I have no access to such beasts I have no idea.
- is not tested with regard to SMP. It will likely crash those boxes or
  at least annihilate performance.

I would be interested in some tests with slower machines. So if you happen
to own that 486 or 90Mhz Pentium give it a try and let me know.

Greetings, Peter


-------------------------------
Email: Peter.Pregler@risc.uni-linz.ac.at
WWW:   http://www.risc.uni-linz.ac.at/people/ppregler
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