Test-Time Optimization in NOC-Based Manycore SOCs Using Multicast Routing

A limitation of prior work on testing of network-onchip (NOC)-based manycore SOCs is that cores are tested using unicast packets; this approach fails to exploit the homogeneity of cores in large manycore SOCs. By leveraging the capability of modern multicast routers to fork a flit to multiple destination ports simultaneously, we present two methods to minimize time to test cores in a homogeneous SOC with many identical cores. First, we formulate the test-time minimization problem in terms of integer linear programming. Next, we add a practical constraint, model the constrained problem in terms of grid partitioning, and apply dynamic programming (DP) to optimally solve it. We present results on synthetic NOC-based SOCs constructed using cores from the ITC'02 benchmarks to show that the proposed methods significantly outperform prior methods based on unicast, and demonstrate the scalability of the DP-based approach for an SOC consisting of more than 1,000 cores.