GemFI: A Fault Injection Tool for Studying the Behavior of Applications on Unreliable Substrates

Dependable computing on unreliable substrates is the next challenge the computing community needs to overcome due to both manufacturing limitations in low geometries and the necessity to aggressively minimize power consumption. System designers often need to analyze the way hardware faults manifest as errors at the architectural level and how these errors affect application correctness. This paper introduces GemFI, a fault injection tool based on the cycle accurate full system simulator Gem5. GemFI provides fault injection methods and is easily extensible to support future fault models. It also supports multiple processor models and ISAs and allows fault injection in both functional and cycle-accurate simulations. GemFI offers fast-forwarding of simulation campaigns via check pointing. Moreover, it facilitates the parallel execution of campaign experiments on a network of workstations. In order to validate and evaluate GemFI, we used it to apply fault injection on a series of real-world kernels and applications. The evaluation indicates that its overhead compared with Gem5 is minimal (up to 3.3%), whereas optimizations such as fast-forwarding via check pointing and execution on NoWs can significantly reduce simulation time of a fault injection campaign.