plan.md

Experiment 06: AoS vs SoA

1. Focus

• Measure how record layout changes memory efficiency for field-oriented GPU work.

2. Question

• Does struct-of-arrays outperform array-of-structs for the same logical particle update?

3. Variants

• aos
• soa

4. Method

• Run the same logical kernel over identical particle data in both layouts.
• Keep the fields touched, arithmetic, and output contract fixed across both variants.

5. Outputs

• Median GPU time by layout.
• Useful-payload GB/s by layout.
• Speedup of soa relative to aos.

6. Interpretation

• Field-wise access usually favors SoA because threads read contiguous values from the same field.
• Any AoS win would need to be explained by a different access shape or reduced address-generation cost.