Tulip: Turn-Free Low-Power Network-on-Chip

The semiconductor industry has seen significant technological advancements, leading to an increase in the number of processing cores in a system-on-chip (SoC). To facilitate communication among the numerous on-chip cores, a network-on-chip (NoC) is employed. One of the main challenges of designing NoCs is power management since the NoC consumes a significant portion of the total power of the SoC. Among the power-intensive components of the NoC, routers stand out. We observe that some power-intensive components of routers, responsible for implementing turn in the mesh topology, are underutilized compared to others. Therefore, we propose Tulip, a turn-free low-power network-in-chip, that avoids within-router turns by removing the corresponding components from the router structure. On a turn (e.g., at the end of the current dimension), Tulip forces the packet to be ejected and then reinjects it to the next dimension channel (i.e., the beginning of the path along the next dimension). Due to its deadlock-free nature, Tulip's scheme may be used orthogonally with any deterministic, partially-adaptive, and fully-adaptive routing algorithms, and can easily be extended for any n-dimensional mesh topology. Our analysis reveals that Tulip can reduce the static power and area by 24%-50% and 25%-55%, respectively, for 2D-5D mesh routers.