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working set

The data a piece of code keeps coming back to over a short stretch of time; it runs fast while that fits in the cache.

The working set of a computation over a time window is the set of distinct lines (or pages) it references in that window; performance drops in steps as the working set outgrows each cache level.

Examples

  • A loop over a 1 MiB array has a 1 MiB working set: too big for many L2 caches, small enough for most L3s.

See also

loop tiling capacity miss
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