>> Speed: 23.2 million iterations per second (512x512 points in parallel per
>> frame at 88 fps)
>>
>> This is on an nVidia FX1700, if I get time I'll try it on my FX7900 
>> tonight,
>> should be significantly faster.
> 
> OK so my FX7900 wasn't that much faster (37 million per second), despite 
> the specs indicating about 5x the pixel throughput.  The speed 
> bottleneck is obviously somewhere else in this code then, probably in 
> the texture lookup in the vertex shader, I guess that isn't very 
> optimised yet.  If I had a DX10 card I could use a geometry shader to 
> cut the number of texture lookups and vertex shader calls by a factor of 
> 4, that would definitely speed things up significantly.

Ooo... profiling GPU code... THAT SOUNDS FUN! o_O

>> I don't know how this compares to how fast a CPU would be, if I get time
>> later I will try out the same on the CPU for comparison.
> 
> Using a single core of an Intel E6400 I get 11 million iterations per 
> second (C++, but with no graphics).

Mmm, OK.

> Also it took me like 5 minutes to write the CPU code from scratch, but 
> several hours to get the GPU code working correctly!

Heh. All hail the day when GHC has a GPU backend! ;-)

(Mind you, apparently Roman Cheplyaka is working on a physics engine 
using Data Parallel Haskell as a Google SoC project. Apparently rigid 
body collision is working already...)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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