Re: Code Feedback Wanted (Generating more garbage)

From: Kenny Tilton (ktilton_at_nyc.rr.com)
Date: 03/25/04

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    Date: Thu, 25 Mar 2004 14:19:37 GMT

    Avant:
    > CL-USER> (time (mandelbrot-set :x -3/4 :zoom 2 :bitmap-width 640 :bitmap-height 640))
    > (MANDELBROT-SET :X -3/4 :ZOOM 2 :BITMAP-WIDTH 640 :BITMAP-HEIGHT 640) took 126,626 milliseconds (126.626 seconds) to run.
    > Of that, 87,830 milliseconds (87.830 seconds) were spent in user mode
    > 32,520 milliseconds (32.520 seconds) were spent in system mode
    > 6,276 milliseconds (6.276 seconds) were spent executing other OS processes.
    > 24,051 milliseconds (24.051 seconds) was spent in GC.
    > 2,252,959,120 bytes of memory allocated.

    Apres:

    > CL-USER> (time (mandelbrot-set :x -3/4 :zoom 2 :bitmap-width 640 :bitmap-height 640))
    > (MANDELBROT-SET :X -3/4 :ZOOM 2 :BITMAP-WIDTH 640 :BITMAP-HEIGHT 640) took 37,353 milliseconds (37.353 seconds) to run.
    > Of that, 29,550 milliseconds (29.550 seconds) were spent in user mode
    > 5,460 milliseconds (5.460 seconds) were spent in system mode
    > 2,343 milliseconds (2.343 seconds) were spent executing other OS processes.
    > 2,881 milliseconds (2.881 seconds) was spent in GC.
    > 466,543,248 bytes of memory allocated.

    Roughly:
             Bef Aft
    User 88 30
    System 33 5
    GC 24 3
    Mem(gb) 2.3 0.5

    Wow. Does anyone know why? Was it the &rest -> non-&rest switch? Duane
    said the switch would be faster but for a different reason, without
    specifying the latter. He also said &rest was efficient if it was (or
    was not?) "dynamic extent". Hunh? Whassat? Examples, plz, I really am
    just an apps guy.

    > For this particular zoom and pixmap size, I can speed things up quite
    > a bit by reducing the *fractional-bits* to 12 and cutting back on the
    > max-iterations without degrading the image. So the other means of
    > getting good results in less time is to algorithmically determine
    > what *fractional-bits* and max-iterations should be for a give pixmap
    > size and zoom factor.
    >

    I am still curious what effect changing the defvars to defconstant would
    do. I do not see those changing during the run. I understand you want to
    make those into parameters eventually. Just curious.

    kt

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