The occupancy of a datapath at a point in time refers to the proportion of the datapath that contains valid data. The occupancy of a circuit over the execution of a program is the average occupancy over time from the moment the program starts to run until it has been completed.
Unoccupied portions of the datapath are often referred to as
. Bubbles are analogous to
no-operation (no-ops) instructions for a CPU that have no effect on the final output.
Decreasing bubbles increase occupancy. In the absence of other bottlenecks, maximizing occupancy of the datapath results in higher throughput.