What does this equation mean?

TOPS , tera-operations per second, measures raw throughput: how many multiply-accumulate operations a chip can, in principle, perform in a second. It says nothing about power, and by itself it is close to useless for comparing edge hardware, because a processor is free to spend arbitrarily large power to hit a large TOPS number. The metric that actually matters for a battery-powered or thermally constrained device is efficiency — operations delivered per unit of energy, conventionally reported as TOPS per watt : $\eta \;=\; \frac{\text{TOPS}}{\text{W}} \;=\; \frac{\text{operations per second}}{\text{power draw (W)}}$. Because a watt is a joule per second, $\eta$ measured this way is numerically the same quantity as operations delivered per joule. That equivalence matters because it converts a throughput specification into an energy budget for a single inference: