Timing Predictability in Future Multi-Core Avionics Systems

Abstract: With more functionality added to safety-critical avionics systems, new platforms are required to offer the computational capacity needed. Multi-core platforms offer a potential that is now being explored, but they pose significant challenges with respect to predictability due to shared resources (such as memory) being accessed from several cores in parallel. Multi-core processors also suffer from higher sensitivity to permanent and transient faults due to shrinking transistor sizes.This thesis addresses several of these challenges. First, we review major contributions that assess the impact of fault tolerance on worst-case execution time of processes running on a multi-core platform. In particular, works that evaluate the timing effects using fault injection methods. We conclude that there are few works that address the intricate timing effects that appear when inter-core interferences due to simultaneous accesses of shared resources are combined with the fault tolerance techniques. We assess the applicability of the methods to COTS multi-core processors used in avionics. We identify dark spots on the research map of the joint problem of hardware reliability and timing predictability for multi-core avionics systems.Next, we argue that the memory requests issued by the real-time operating systems (RTOS) must be considered in resource-monitoring systems to ensure proper execution on all cores.We also adapt and extend an existing method for worst-case response time analysis to fulfill the specific requirements of avionics systems. We relax the requirement of private memory banks to also allow cores to share memory banks.