Re: [PARPORT] ECP, DMA, driver writing

From: Peter Pregler (
Date: Fri Jun 23 2000 - 18:22:57 EDT

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    On Fri, Jun 23, 2000 at 03:39:39PM -0500, Richard Bonomo wrote:
    > > This is about what my parport webcam driver does, see cpia_pp.c in the
    > > 2.2.16 kernel. However my LARGE (about 300K IIRC) might not be as LARGE
    > > as yours. ;)
    > Is that available at or
    > (Is it possible to get just the webcam driver?)



    > Do you think that DMA offers a speed advantage over interrupt-driven
    > programmed i/o, given the additional overhead?

    It will definitly make the cpu way happier. CPU-utilization dropped
    from about 60% to less than 10% on a 350MHz PIII in my case during full
    times of thruput. But as long as you have cycles to burn it might not
    bring you any improved thruput. Though I used a sort of polling PIO but
    no busy waiting. According to my tests the polling was not the cause
    for the CPU-usage.


    Even the thought that a ship was waiting to take him back to Earth
    did not wipe out the sense of loss he felt at that moment.

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