Soft error sensitivity characterization for microprocessor dependability enhancement strategy

This paper presents an empirical investigation on the soft error sensitivity (SES) of microprocessors, using the picoJava-II as an example, through software simulated fault injections in its RTL model. Soft errors are generated under a realistic fault model during program run-time. The SES of a processor logic block is defined as the probability that a soft error in the block causes the processor to behave erroneously or enter into an incorrect architectural state. The SES is measured at the functional block level. We have found that highly error-sensitive blocks are common for various workloads. At the same time soft errors in many other logic blocks rarely affect the computation integrity. Our results show that a reasonable prediction of the SES is possible by deduction from the processor's microarchitecture. We also demonstrate that the sensitivity-based integrity checking strategy can be an efficient way to improve fault coverage per unit redundancy.