Criticality-aware scrubbing mechanism for SRAM-based FPGAs

Abstract

Scrubbing has been considered as an effective mechanism to provide fault-tolerance in Static-RAM (SRAM)-based Field Programmable Gate Arrays (FPGAs). However, the current scrubbing techniques execute without considering the criticality and timing of the user tasks implemented in the FPGA. They often do not execute the scrubbing process in the right instant, which minimizes the probability of each task being executed without transient faults. Moreover, these current solutions are not adapted to the tasks' fault-tolerance requirements, since they may not properly protect the most critical tasks in the system. However, if they do it, they waste resources with the less critical tasks. In this paper, a new scrubbing mechanism is proposed. This new approach adapts the scrubbing mechanism to the tasks' execution, by a proper scheduling and according to their criticality. A proposed heuristic finds a feasible scrubbing schedule for each hardware task. Firstly, the minimum scrubbing periods are computed according to the criticality of each implemented hardware task. Secondly, a proper scrubbing schedule following the EDL (Earliest Deadline as Late as possible) algorithm is found, maximizing the reliability of the system. The experimental results show up to 79% improvements on the system reliability, achieved without wasting scrubbing resources.