基于周期粒度的级间寄存器备份机制

Backup Mechanism of Pipeline Register Based on Cycle Granularity

单粒子翻转是空间环境下微处理器发生异常的重要诱因之一,随着集成电路特征尺寸的缩小,单粒子翻转不仅会引发单位错误,还会引发大量的多位错误,如何有效解决处理器所面临的多位故障是容错处理器设计面临的新挑战.本文提出了一种基于周期粒度的级间寄存器备份机制的容错方法,采用双流水线冗余结构,通过比较器对比两条流水线的级间寄存器以检测单粒子故障;以周期粒度对级间寄存器的内容进行备份,当检测到单粒子故障时,使用2个周期对流水线进行恢复;为避免脏数据流出流水线,在数据缓存和寄存器堆的入口设置写缓冲,通过延迟写入保证信息可靠性.本文基于实际的SPARC V8结构处理器,对提出的方法进行了具体实现,在实验平台上进行了仿真,仿真结果显示,本文提出的容错方法能够以一定的面积开销实现对SEU、SET、和MBU故障容错,加固处理器的主频最高可以提升70%.

SEU is one of the important causes for the microprocessor in which the exception occurs in space environment.SEU not only causes single-bit error,but does lead to a number of multi-bit errors,along with the reduction of the IC feature size.It is a great challenge that we find a way to effectively cope with the multi-bit error.This paper proposes a fault-tolerant method which backs up the pipeline registers based on cycle granularity,the dual modular redundancy is applied in this method.The pipeline registers on the two pipelines are compared through the comparators to detect the error and the pipeline registers are backed up based on cycle granularity.It takes two cycles to restore the error pipeline when the error is detected.The write buffer is set in the entrance to the data cache and register file to avoid dirty data flowing out of the pipeline.And we can ensure the data is correct through delay write.This paper implements the fault-tolerant method based on SPARC V8 processor and tests in the simulation environment.The simulation results shows that the CPU clock speed of the hardened processor in which the proposed fault-tolerant method is applied can increase 70%at most and the fault-tolerance of the SEU,SET and MBU is implemented with the limited area overhead.