Fine-grained hardware/software methodology for process migration in MPSoCs

Process migration (PM) is a method used in Multi-Processor System on Chips (MPSoCs) to improve reliability, reduce thermal hotspots and balance loads. However, existing PM approaches are limited by coarse granularity (i.e. can only switch at application or operating systems boundaries), and thus respond slowly. Such slow response does not allow for fine control over temperature, nor does it allow frequent migration which is necessary in certain systems. In this paper, we propose Thor, an approach which is a fine-grained reliable PM scheme, for Embedded MPSoCs, to overcome the limitations of existing PM approaches. Our approach leverages custom instructions to integrate a base processor architecture, with PM functionality. We have proposed three schemes, Thor-BM (migration at basic block boundaries), Thor-BM/CR (migration at basic block boundaries with checkpoint and recovery), and ThorIM/CR (migration at instruction level with checkpoint and recovery). Our experiments show that the execution time overhead is less than 2%, while the additional area cost and power consumption costs are approximately 50% (excluding main memories, which if taken into account would substantially decrease this overhead). The average migration time cost is 289 cycles.