Performance-Asymmetry-Aware Topology Virtualization for Defect-Tolerant NoC-Based Many-Core Processors

Topology virtualization techniques are proposed for NoCbased many-core processors with core-level redundancy to isolate hardware changes caused by on-chip defective cores. Prior work focuses on homogeneous cores with symmetric performance and optimizes on-chip communication only. However, core-to-core performance asymmetry due to manufacturing process variations poses new challenges for constructing virtual topologies. Lower performance cores may scatter over a virtual topology, while operating systems typically allocate tasks to continuous cores. As a result, parallel applications are probably assigned to a region containing many slower cores that become bottlenecks. To tackle the above problem, this paper presents a novel performance-asymmetry-aware reconfiguration algorithm Bubble-Up based on a new metric called Core Fragmentation Factor (CFF).