Energy-Efficient Cache Coherence Protocol for NoC-based MPSoCs

As the number of cores and functionalities integrated in embedded devices increases, the amount of memory used on these devices also increases, justifying the development of memory architectures presenting scalability, low energy consumption and low latency. To implement memory solutions, most works adopting NoC-based MPSoCs only employ basic communication services, such as send/receive, without exploring the services NoCs can offer, for instance connection, priorities and multicast communication. Multicast can be used to optimize the cache coherence protocol, leading to both traffic and energy consumption reduction. The goal of this work is to optimize a directory-based cache coherence protocol exploiting specific NoC services, as multicast and priorities. To demonstrate our proposal, an MPSoC described at the RTL level is used, enabling accurate performance and energy evaluation. Results show a reduction of 17% in the number of clock cycles and a reduction up to 86% (average reduction: 39%) in energy consumption for some memory transactions.