Iris

On-chip communication, including short, often-multicast, latency-critical coherence and synchronization messages, and long, unicast, throughput-sensitive data transfers, limits the power efficiency and performance scalability of many-core chip-multiprocessor systems. This article analyzes on-chip communication challenges and studies the characteristics of existing electrical and emerging nanophotonic interconnect. Iris, a CMOS-compatible high-performance low-power nanophotonic on-chip network, is thus introduced. Iris's circuit-switched subnetwork supports throughput-sensitive data transfer. Iris's optical-antenna-array-based broadcast--multicast subnetwork optimizes latency-critical traffic and supports the path setup of circuit-switched communication. Overall, the proposed nanophotonic network design offers an on-chip communication backplane that is power efficient while demonstrating low latency and high throughput.