Efficient Multicast Routing in Reconfigurable Networks-on-Chip

Several routing algorithms have been presented for multicast and unicast traffic in MPSoCs. Multicast protocols in NoCs are used for clock synchronization, cache coherency in distributed shared memory on-chip multiprocessors, replication and barrier synchronization. Unicast routing algorithms are not useful for multicast. Indeed, when unicast routing algorithms are employed to realize multicast operation, high traffic, congestion and deadlock are imposed to the network. To prevent from these problems, Tree-based and path based techniques have been proposed for multicast in multicomputers (and recently NoCs). In this paper, we present a new multicast routing method to decrease power consumption and multicast message latency based on a reconfigurable NoC architecture. In this line, we benefit from simple switches in our reconfigurable architecture instead of routers; we then divide the network to smaller partitions to make better trees for conducting multicast packets. Our evaluation results reveal that, for both real and synthetic traffic loads, the proposed method outperforms the baseline tree-based routing method in a reconfigurable mesh, and reduces message latency by up to 51% and power consumption by up to 33%.