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Systems · hard

48. Memory Layout and Optimisation

Sizes, alignment and cache behaviour.

Struct field order affects padding; enums size to their largest variant plus a discriminant. Box large rare variants to shrink hot types. Prefer contiguous Vec over pointer-chasing structures for cache locality, and measure with size_of and profilers.

Check your understanding

  1. 1. Enum size is driven by…

  2. 2. How can you shrink a big rare variant?