Slide 13 of 16
EXAMPLE: Tweaking C to optimise assembler output for Mandelbrot curve program on Sun 3/60 beat the published top speed of the FPU and the code remained portable!
- Do you know what you are tuning for?
- If more than one, rank, weight and measure.
- Do you have the right tool or tools?
- Have you looked at your compiler output, bus activity, etc?
- Do you know what your tools cannot see? (Eg many tools canít see cache misses and pipeline empties.)
- Do you understand the relative speeds (etc) of RAM vs ROM storage of code and data?
- Do you know how to tune instructions for different processor versions (eg blends on VC and SPARCompiler) or different cache styles (SPARCompiler)?