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Oh dear. I really should know better than to get into a benchmark battle, but...

The Trackman2 results intrigued me, so I had a quick look into it. Taking the program as it is, the top-level fractal renders in 0.16 seconds on my Risc PC and 0.42 seconds on my Iyonix. However, this program is unusual in that it does all its calculations in screen memory, constantly reading and writing screen memory bytes, which is not a sensible thing to do on an Iyonix since the screen memory is the other side of the PCI bus, and the graphics card is not optimised for screen memory reads.

I then updated the code to plot into a buffer in main RAM and only copy the results to the screen when it had finished. Result - the top-level fractal now takes 0.06 seconds to plot, and generally the plotting times now seem to be 2.5ish times faster than the Risc PC, which is what you'd expect given the difference in clock speeds.

What does this tell us? 1) Benchmarks will tell you anything you want them to. 2) A little time spent optimising (less than one hour) can yield large benefits (a 700% speed increase in this case). 3) Er, that's it.

James

P.S. Trackman2 is not 32bit safe. It contains three LDM Rx,{...,PC}^ instructions. I fixed these too.

 is a RISC OS Userjbyrne on 3/3/03 11:27PM
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