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    SubjectRe: Good news for SPARC/Linux
    David F. Newman writes:
    > On 10 Dec 1998, Matthias Urlichs wrote:
    >
    > > Needless to say, I want one of these... though I wonder if there is _any_
    > > real-world application which 14 CPUs would speed up 14 times.
    >
    > I could easily use all 14 CPUs when ray tracing. Either having
    > each CPU render an individual frame of an animation, or giving
    > each CPU a piece of a still image to render. It is highly
    > math intensive with io only when an image is completed. A
    > perfect application for SMP.

    Indeed. But what about your input dataset? How big is your scene data?
    I find with volume rendering the memory bus starts to saturate,
    because each processor has to hit the same volume data (needless to
    say, the volume data doesn't fit into cache).

    When we got our SGI Power Challenge XL in 1995 (10x 75 MHz r8000), I
    saw ~8x speedup (77% parallel efficiency). With 4 CPUs I got 3.83x
    speedup (96% efficiency).

    A couple of years later I benchmarked a Sun E6000 with 10 CPUs. Again
    the same 8x speedup. It looks like the CPU/bandwidth ratios didn't
    change much.

    This is why I got excited at the launch of the Origin 2000 when I saw
    distributed memory and heard mention of automatic page migration, but
    still with an SMP model (or made to look that way). Haven't organised
    a benchmark yet, though :-(

    Regards,

    Richard....

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