A greedy approach to tolerate defect cores for multimedia applications

Computation-intensive multimedia applications are emerging on mobile devices. System-on-Chip (SoC) offers high performance at a decreased size for these devices. SoC often integrates tens of cores and uses Network-on-Chip (NoC) as its communication infrastructure. To ensure high yield of manycore processors, core-level redundancy is often used as an effective approach to improve the reliability of manycore chips. However, when defective cores are replaced by redundant ones, the NoC topology changes. As a result, a fine-tuned application based on timing parameters given by one topology may not meet the expected timing behavior under the new one. To address this issue, we first define a metric that can measure the timing resemblance between different NoC topologies. Based on this metric, we develop a greedy algorithm to reconfigure a defect-tolerant manycore platform and form a unified application specific virtual topology on which the timing variations caused by the reconfiguration are minimized. Our simulation results clearly indicate the effectiveness of the developed algorithm.