System management recovery in NoC-based many-core systems

Abstract

The technology nodes reduction enabled the emergence of NoC-based many-cores with dozens to hundreds of processing elements (PEs). Despite the processing power offered by a large number of processors and communication flexibility due to the adoption of NoCs, it is necessary to manage the many-core resources to ensure scalability. The execution of the management tasks requires a PE reserved exclusively to execute such actions. These processors are named managers PE-MPE. A centralized approach would induce a significant load to the MPE in large-scale systems, and a permanent fault in the MPE would compromise the entire system. The adoption of a distributed approach, organization adopted in this work, with MPEs hierarchically organized, reduces the management load, and a fault in an MPE would compromise only the PEs managed by the faulty MPE. The literature presents several fault-tolerant proposals targeting the NoC or the processors. However, there is a significant gap related to fault-tolerant methods at the system level, i.e., related to fault-tolerant techniques regarding the MPEs. The goal of this paper is to present a recovery method when an MPE became faulty, and propose a protocol to migrate the management software safely to a new PE. The method adopts task migration to release a processor if there is no processor to receive the kernel that was executing in a faulty processor. The proposal is transparent to the applications running in the many-core, with an overhead in the execution time varying between 1.5 and 1.65 ms during the management and task migration.