Array utilization
Beginner
The share of the time the calculator cells are doing useful work. 100% would mean every cell is busy on every tick.
Novice
Useful multiply-accumulates done divided by the most the array could have done in the same time (number of PEs × cycles). Not to be confused with placement utilization in chip layout.
Expert
. It falls with fill/drain, matrix shapes that don’t fill the array (fragmentation), stalls waiting for weights or memory, and small batches. TPU v1 averaged 23% useful MACs across six production apps.
Explained in Systolic arrays (Architectures).
See also: Fill and drain, Tiling (folding).