Structure of Arrays vs Array of Structures Benchmark

Layout Follows Access Pattern

Array of Structures (AoS) stores all fields per object together. Structure of Arrays (SoA) stores each field in its own contiguous array. Game engines and SIMD kernels prefer SoA when loops touch one field across many entities. AoS wins when you always load whole records together.

When Each Wins

Updating positions for 100k particles: SoA lets you vectorize x[], y[], z[] without gathering scattered fields. Printing full records: AoS avoids three pointer chases.

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• SoA improves bandwidth when only one field is hot
• AoS can false-share if threads update different fields in the same struct
• Hybrid layouts (hot SoA, cold AoS) appear in ECS architectures
• Measure the actual loop you ship, not a synthetic mix

Working Through the Exercise

Keep the relevant documentation open while you implement. When your output disagrees with the reference, trace one failing case by hand before changing random lines.

• Trace first: walk one failing input step by step
• Read the manual: skim the official doc for the mechanism named in this task
• Compare baselines: save measurements from the prior step so speedups are honest

Why for this exercise

You will benchmark AoS vs SoA for a field-heavy update loop and report speedup. This exercise asks you to tie the winner to which fields the inner loop reads.