FoldedHexaTorus: An Inter-Chiplet Interconnect Topology for Chiplet-based Systems using Organic and Glass Substrates
Patrick Iff, Maciej Besta, Torsten Hoefler
TL;DR
This paper addresses high-throughput inter-chiplet communication for chiplet-based systems on organic and glass substrates. It formalizes three design principles—minimize network diameter, use a short link-range, and minimize network radix—and derives FoldedHexaTorus, a six-radix topology with range-one links and diameter below $\sqrt{N}$, as a principled solution. Through extensive simulation and tracing across substrate types and chiplet counts, FoldedHexaTorus consistently achieves superior throughput and low latency with modest area and power overhead, outperforming baselines designed for silicon interposers. The work also discusses manufacturing considerations, notably hexagonal chiplet layouts that align with organic/glass fabrication, underscoring practical impact for next-generation chiplet systems.
Abstract
Chiplet-based systems are rapidly gaining traction in the market. Two packaging options for such systems are the established organic substrates and the emerging glass substrates. These substrates are used to implement the inter-chiplet interconnect (ICI), which is crucial for overall system performance. To guide the development of ICIs, we introduce three design principles for ICI network topologies on organic and glass substrates. Based on our design principles, we propose the novel FoldedHexaTorus network topology. Our evaluation shows that the FoldedHexaTorus achieves significantly higher throughput than state-of-the-art topologies while maintaining low latency.