Zero-performance-overhead online fault detection and diagnosis in 3D stacked integrated circuits

In this paper we present a zero-performance-overhead online fault detection and diagnosis scheme that exploits the vertical proximity of hardware inherent in 3D stacked integrated circuits (3D-SIC). We consider a 3D stacked processor executing independent instruction streams from different threads, on each die. We propose the vertical clustering of functionally identical computational blocks in order to enable the utilization of the 3D specific low-latency interlayer communication infrastructure. The clustering facilitates the parallel re-execution of instructions on idle units located in the proximity of the units which initially computed them and in this way creates the means for fault diagnosis and detection. We detail the control, interconnection communication infrastructure, instruction distribution, and results processing policies required for our scheme. To determine the effectiveness of the approach, we evaluate its performance in terms of diagnosis latency and percentage of verified operations on 3 to 8 core processors implemented on 3 to 8 tier 3D-SICs, respectively, by means of simulations. Our experiments indicate that the diagnosis latency ranges from 9 to 5 cycles, for 3 to 8 cores, respectively. For transient fault detection our simulations indicate that 86% to 94% of all executed instructions are verified, for 3 to 8 cores, respectively. When only one of the layers is protected against transient faults the number of verified operations increases to 94% to 99%, for the same simulation conditions. This suggests that, if certain conditions are fulfilled at design time, our approach can completely protect one instruction stream identified as being critical for the application. Our simulations clearly indicate that the proposed scheme has the potential to improve the 3D stacked integrated circuits dependability with no performance overhead and at the expense of little area overhead.