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Rent's rule

Rent's rule [53,54] states that the following relationship exists between several chip parameters.

\begin{displaymath}
T = AK^P \end{displaymath}

where $T$ is the number of terminals, $K$ the number of blocks within the chip, $A$ the average number of terminals for one block and $p$ the Rent exponent. Rent's rule has been widely used to estimate power dissipation in interconnects. In [55], it is used to estimate the number of interconnects. The total interconnect power dissipation is estimated based on that number, average interconnect length and average fanout number for interconnect. In [56], the authors obtained a stochastic distribution of wire length with the assumption that the same $p$ and $A$ hold for the chip as well as its different parts. They used the distribution to estimate wire power dissipation in [57]. The assumptions made about $p$ and $A$, e.g., their values and whether they are constant, render the methodology barely useful for design space exploration. In high-level synthesis, different binding and scheduling algorithms may generate circuits with different $p$ and $A$, as illustrated in Fig. 5.
next up previous
Next: Steering logic Up: Data transfer wires Previous: RTL data transfer power
Lin Zhong 2003-10-11